The ti-sn65dsi86 MIPI DSI to eDP bridge chip has 4 pins on it that can be used as GPIOs in a system. Each pin can be configured as input, output, or a special function for the bridge chip. These are: - GPIO1: SUSPEND Input - GPIO2: DSIA VSYNC - GPIO3: DSIA HSYNC or VSYNC - GPIO4: PWM

Let's expose these pins as GPIOs. A few notes: - Access to ti-sn65dsi86 is via i2c so we set "can_sleep". - These pins can't be configured for IRQ. - There are no programmable pulls or other fancy features. - Keeping the bridge chip powered might be expensive. The driver is setup such that if all used GPIOs are only inputs we'll power the bridge chip on just long enough to read the GPIO and then power it off again. Setting a GPIO as output will keep the bridge powered. - If someone releases a GPIO we'll implicitly switch it to an input so we no longer need to keep the bridge powered for it.

Because of all of the above limitations we just need to implement a bare-bones GPIO driver. The device tree bindings already account for this device being a GPIO controller so we only need the driver changes for it.

NOTE: Despite the fact that these pins are nominally muxable I don't believe it makes sense to expose them through the pinctrl interface as well as the GPIO interface. The special functions are things that the bridge chip driver itself would care about and it can just configure the pins as needed.

Signed-off-by: Douglas Anderson dianders@chromium.org Cc: Linus Walleij linus.walleij@linaro.org Cc: Bartosz Golaszewski bgolaszewski@baylibre.com ---

Changes in v3: - Becaue => Because - Add a kernel-doc to our pdata to clarify double-duty of gchip_output. - More comments about how powering off affects us (get_dir, dir_input). - Cleanup tail of ti_sn_setup_gpio_controller() to avoid one "return". - Use a bitmap rather than rolling my own.

Changes in v2: - ("Export...GPIOs") is 1/2 of replacement for ("Allow...bridge GPIOs")

drivers/gpu/drm/bridge/ti-sn65dsi86.c | 194 ++++++++++++++++++++++++++ 1 file changed, 194 insertions(+)

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c index 6ad688b320ae..fcd817835c43 100644 --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c @@ -7,6 +7,8 @@ #include <linux/clk.h> #include <linux/debugfs.h> #include <linux/gpio/consumer.h> +#include <linux/gpio/driver.h> +#include <linux/gpio.h> #include <linux/i2c.h> #include <linux/iopoll.h> #include <linux/module.h> @@ -54,6 +56,13 @@ #define BPP_18_RGB BIT(0) #define SN_HPD_DISABLE_REG 0x5C #define HPD_DISABLE BIT(0) +#define SN_GPIO_IO_REG 0x5E +#define SN_GPIO_INPUT_SHIFT 4 +#define SN_GPIO_OUTPUT_SHIFT 0 +#define SN_GPIO_CTRL_REG 0x5F +#define SN_GPIO_MUX_INPUT 0 +#define SN_GPIO_MUX_OUTPUT 1 +#define SN_GPIO_MUX_SPECIAL 2 #define SN_AUX_WDATA_REG(x) (0x64 + (x)) #define SN_AUX_ADDR_19_16_REG 0x74 #define SN_AUX_ADDR_15_8_REG 0x75 @@ -88,6 +97,31 @@

#define SN_REGULATOR_SUPPLY_NUM 4

+#define SN_NUM_GPIOS 4 + +/** + * struct ti_sn_bridge - Platform data for ti-sn65dsi86 driver. + * @dev: Pointer to our device. + * @regmap: Regmap for accessing i2c. + * @aux: Our aux channel. + * @bridge: Our bridge. + * @connector: Our connector. + * @debugfs: Used for managing our debugfs. + * @host_node: Remote DSI node. + * @dsi: Our MIPI DSI source. + * @refclk: Our reference clock. + * @panel: Our panel. + * @enable_gpio: The GPIO we toggle to enable the bridge. + * @supplies: Data for bulk enabling/disabling our regulators. + * @dp_lanes: Count of dp_lanes we're using. + * + * @gchip: If we expose our GPIOs, this is used. + * @gchip_output: A cache of whether we've set GPIOs to output. This + * serves double-duty of keeping track of the direction and + * also keeping track of whether we've incremented the + * pm_runtime reference count for this pin, which we do + * whenever a pin is configured as an output. + */ struct ti_sn_bridge { struct device *dev; struct regmap *regmap; @@ -102,6 +136,9 @@ struct ti_sn_bridge { struct gpio_desc *enable_gpio; struct regulator_bulk_data supplies[SN_REGULATOR_SUPPLY_NUM]; int dp_lanes; + + struct gpio_chip gchip; + DECLARE_BITMAP(gchip_output, SN_NUM_GPIOS); };

static const struct regmap_range ti_sn_bridge_volatile_ranges[] = { @@ -874,6 +911,157 @@ static int ti_sn_bridge_parse_dsi_host(struct ti_sn_bridge *pdata) return 0; }

+static struct ti_sn_bridge *gchip_to_pdata(struct gpio_chip *chip) +{ + return container_of(chip, struct ti_sn_bridge, gchip); +} + +static int ti_sn_bridge_gpio_get_direction(struct gpio_chip *chip, + unsigned int offset) +{ + struct ti_sn_bridge *pdata = gchip_to_pdata(chip); + + /* + * We already have to keep track of the direction because we use + * that to figure out whether we've powered the device. We can + * just return that rather than (maybe) powering up the device + * to ask its direction. + */ + return test_bit(offset, pdata->gchip_output) ? + GPIOF_DIR_OUT : GPIOF_DIR_IN; +} + +static int ti_sn_bridge_gpio_get(struct gpio_chip *chip, unsigned int offset) +{ + struct ti_sn_bridge *pdata = gchip_to_pdata(chip); + unsigned int val; + int ret; + + /* + * When the pin is an input we don't forcibly keep the bridge + * powered--we just power it on to read the pin. NOTE: part of + * the reason this works is that the bridge defaults (when + * powered back on) to all 4 GPIOs being configured as GPIO input. + * Also note that if something else is keeping the chip powered the + * pm_runtime functions are lightweight increments of a refcount. + */ + pm_runtime_get_sync(pdata->dev); + ret = regmap_read(pdata->regmap, SN_GPIO_IO_REG, &val); + pm_runtime_put(pdata->dev); + + if (ret) + return ret; + + return (val >> (SN_GPIO_INPUT_SHIFT + offset)) & 1; +} + +static void ti_sn_bridge_gpio_set(struct gpio_chip *chip, unsigned int offset, + int val) +{ + struct ti_sn_bridge *pdata = gchip_to_pdata(chip); + int ret; + + if (!test_bit(offset, pdata->gchip_output)) { + dev_err(pdata->dev, "Ignoring GPIO set while input\n"); + return; + } + + val &= 1; + ret = regmap_update_bits(pdata->regmap, SN_GPIO_IO_REG, + BIT(SN_GPIO_OUTPUT_SHIFT + offset), + val << (SN_GPIO_OUTPUT_SHIFT + offset)); +} + +static int ti_sn_bridge_gpio_direction_input(struct gpio_chip *chip, + unsigned int offset) +{ + struct ti_sn_bridge *pdata = gchip_to_pdata(chip); + int shift = offset * 2; + int ret; + + if (!test_and_clear_bit(offset, pdata->gchip_output)) + return 0; + + ret = regmap_update_bits(pdata->regmap, SN_GPIO_CTRL_REG, + 0x3 << shift, SN_GPIO_MUX_INPUT << shift); + if (ret) { + set_bit(offset, pdata->gchip_output); + return ret; + } + + /* + * NOTE: if nobody else is powering the device this may fully power + * it off and when it comes back it will have lost all state, but + * that's OK because the default is input and we're now an input. + */ + pm_runtime_put(pdata->dev); + + return 0; +} + +static int ti_sn_bridge_gpio_direction_output(struct gpio_chip *chip, + unsigned int offset, int val) +{ + struct ti_sn_bridge *pdata = gchip_to_pdata(chip); + int shift = offset * 2; + int ret; + + if (test_and_set_bit(offset, pdata->gchip_output)) + return 0; + + pm_runtime_get_sync(pdata->dev); + + /* Set value first to avoid glitching */ + ti_sn_bridge_gpio_set(chip, offset, val); + + /* Set direction */ + ret = regmap_update_bits(pdata->regmap, SN_GPIO_CTRL_REG, + 0x3 << shift, SN_GPIO_MUX_OUTPUT << shift); + if (ret) { + clear_bit(offset, pdata->gchip_output); + pm_runtime_put(pdata->dev); + } + + return ret; +} + +static void ti_sn_bridge_gpio_free(struct gpio_chip *chip, unsigned int offset) +{ + /* We won't keep pm_runtime if we're input, so switch there on free */ + ti_sn_bridge_gpio_direction_input(chip, offset); +} + +static const char * const ti_sn_bridge_gpio_names[SN_NUM_GPIOS] = { + "GPIO1", "GPIO2", "GPIO3", "GPIO4" +}; + +static int ti_sn_setup_gpio_controller(struct ti_sn_bridge *pdata) +{ + int ret; + + /* Only init if someone is going to use us as a GPIO controller */ + if (!of_property_read_bool(pdata->dev->of_node, "gpio-controller")) + return 0; + + pdata->gchip.label = dev_name(pdata->dev); + pdata->gchip.parent = pdata->dev; + pdata->gchip.owner = THIS_MODULE; + pdata->gchip.free = ti_sn_bridge_gpio_free; + pdata->gchip.get_direction = ti_sn_bridge_gpio_get_direction; + pdata->gchip.direction_input = ti_sn_bridge_gpio_direction_input; + pdata->gchip.direction_output = ti_sn_bridge_gpio_direction_output; + pdata->gchip.get = ti_sn_bridge_gpio_get; + pdata->gchip.set = ti_sn_bridge_gpio_set; + pdata->gchip.can_sleep = true; + pdata->gchip.names = ti_sn_bridge_gpio_names; + pdata->gchip.ngpio = SN_NUM_GPIOS; + ret = devm_gpiochip_add_data(pdata->dev, &pdata->gchip, pdata); + if (ret) + dev_err(pdata->dev, "can't add gpio chip\n"); + + return ret; +} + static int ti_sn_bridge_probe(struct i2c_client *client, const struct i2c_device_id *id) { @@ -937,6 +1125,12 @@ static int ti_sn_bridge_probe(struct i2c_client *client,

pm_runtime_enable(pdata->dev);

+ ret = ti_sn_setup_gpio_controller(pdata); + if (ret) { + pm_runtime_disable(pdata->dev); + return ret; + } + i2c_set_clientdata(client, pdata);

pdata->aux.name = "ti-sn65dsi86-aux";

In the cases where there is no connector in a system there's no great place to put "hpd-gpios". As per discussion [1] the best place to put it is in the panel. Add this to the device tree bindings.

[1] https://lore.kernel.org/r/20200417180819.GE5861@pendragon.ideasonboard.com

Signed-off-by: Douglas Anderson dianders@chromium.org Reviewed-by: Stephen Boyd swboyd@chromium.org ---

Changes in v3: None Changes in v2: - ("dt-bindings: display: Add hpd-gpios to panel-common...") new for v2

.../devicetree/bindings/display/panel/panel-common.yaml | 6 ++++++ 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/panel/panel-common.yaml b/Documentation/devicetree/bindings/display/panel/panel-common.yaml index ed051ba12084..e9a04a3a4f5f 100644 --- a/Documentation/devicetree/bindings/display/panel/panel-common.yaml +++ b/Documentation/devicetree/bindings/display/panel/panel-common.yaml @@ -96,6 +96,12 @@ properties: (hot plug detect) signal, but the signal isn't hooked up so we should hardcode the max delay from the panel spec when powering up the panel.

+ hpd-gpios: + maxItems: 1 + description: + If Hot Plug Detect (HPD) is connected to a GPIO in the system rather + than a dedicated HPD pin the pin can be specified here. + # Control I/Os

# Many display panels can be controlled through pins driven by GPIOs. The nature

People use panel-simple when they have panels that are builtin to their device. In these cases the HPD (Hot Plug Detect) signal isn't really used for hotplugging devices but instead is used for power sequencing. Panel timing diagrams (especially for eDP panels) usually have the HPD signal in them and it acts as an indicator that the panel is ready for us to talk to it.

Sometimes the HPD signal is hooked up to a normal GPIO on a system. In this case we need to poll it in the correct place to know that the panel is ready for us. In some system designs the right place for this is panel-simple.

When adding this support, we'll account for the case that there might be a circular dependency between panel-simple and the provider of the GPIO. The case this was designed for was for the "ti-sn65dsi86" bridge chip. If HPD is hooked up to one of the GPIOs provided by the bridge chip then in our probe function we'll always get back -EPROBE_DEFER. Let's handle this by allowing this GPIO to show up late if we saw -EPROBE_DEFER during probe. NOTE: since the gpio_get_optional() is used, if the "hpd-gpios" isn't there our variable will just be NULL and we won't do anything in prepare().

Signed-off-by: Douglas Anderson dianders@chromium.org Reviewed-by: Stephen Boyd swboyd@chromium.org ---

Changes in v3: - Remind how gpio_get_optional() works in the commit message.

Changes in v2: - ("simple...hpd-gpios") is 1/2 of replacement for ("Allow...bridge GPIOs")

drivers/gpu/drm/panel/panel-simple.c | 53 ++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c index 3ad828eaefe1..f816e2aa29cd 100644 --- a/drivers/gpu/drm/panel/panel-simple.c +++ b/drivers/gpu/drm/panel/panel-simple.c @@ -23,6 +23,7 @@

#include <linux/delay.h> #include <linux/gpio/consumer.h> +#include <linux/iopoll.h> #include <linux/module.h> #include <linux/of_platform.h> #include <linux/platform_device.h> @@ -108,6 +109,7 @@ struct panel_simple { struct i2c_adapter *ddc;

struct gpio_desc *enable_gpio; + struct gpio_desc *hpd_gpio;

struct drm_display_mode override_mode; }; @@ -259,11 +261,37 @@ static int panel_simple_unprepare(struct drm_panel *panel) return 0; }

+static int panel_simple_get_hpd_gpio(struct device *dev, + struct panel_simple *p, bool from_probe) +{ + int err; + + p->hpd_gpio = devm_gpiod_get_optional(dev, "hpd", GPIOD_IN); + if (IS_ERR(p->hpd_gpio)) { + err = PTR_ERR(p->hpd_gpio); + + /* + * If we're called from probe we won't consider '-EPROBE_DEFER' + * to be an error--we'll leave the error code in "hpd_gpio". + * When we try to use it we'll try again. This allows for + * circular dependencies where the component providing the + * hpd gpio needs the panel to init before probing. + */ + if (err != -EPROBE_DEFER || !from_probe) { + dev_err(dev, "failed to get 'hpd' GPIO: %d\n", err); + return err; + } + } + + return 0; +} + static int panel_simple_prepare(struct drm_panel *panel) { struct panel_simple *p = to_panel_simple(panel); unsigned int delay; int err; + int hpd_asserted;

if (p->prepared) return 0; @@ -282,6 +310,26 @@ static int panel_simple_prepare(struct drm_panel *panel) if (delay) msleep(delay);

+ if (p->hpd_gpio) { + if (IS_ERR(p->hpd_gpio)) { + err = panel_simple_get_hpd_gpio(panel->dev, p, false); + if (err) + return err; + } + + err = readx_poll_timeout(gpiod_get_value_cansleep, p->hpd_gpio, + hpd_asserted, hpd_asserted, + 1000, 2000000); + if (hpd_asserted < 0) + err = hpd_asserted; + + if (err) { + dev_err(panel->dev, + "error waiting for hpd GPIO: %d\n", err); + return err; + } + } + p->prepared = true;

return 0; @@ -462,6 +510,11 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc) panel->desc = desc;

panel->no_hpd = of_property_read_bool(dev->of_node, "no-hpd"); + if (!panel->no_hpd) { + err = panel_simple_get_hpd_gpio(dev, panel, true); + if (err) + return err; + }

panel->supply = devm_regulator_get(dev, "power"); if (IS_ERR(panel->supply))

This moves the bindings over, based a lot on toshiba,tc358768.yaml. Unless there's someone known to be better, I've set the maintainer in the yaml as the first person to submit bindings.

Signed-off-by: Douglas Anderson dianders@chromium.org ---

Changes in v3: None Changes in v2: - specification => specifier. - power up => power. - Added back missing suspend-gpios. - data-lanes and lane-polarities are are the right place now. - endpoints don't need to be patternProperties. - Specified more details for data-lanes and lane-polarities. - Added old example back in, fixing bugs in it. - Example i2c bus is just called "i2c", not "i2c1" now.

.../bindings/display/bridge/ti,sn65dsi86.txt | 87 ------ .../bindings/display/bridge/ti,sn65dsi86.yaml | 279 ++++++++++++++++++ 2 files changed, 279 insertions(+), 87 deletions(-) delete mode 100644 Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.txt create mode 100644 Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml

diff --git a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.txt b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.txt deleted file mode 100644 index 8ec4a7f2623a..000000000000 --- a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.txt +++ /dev/null @@ -1,87 +0,0 @@ -SN65DSI86 DSI to eDP bridge chip --------------------------------- - -This is the binding for Texas Instruments SN65DSI86 bridge. -http://www.ti.com/general/docs/lit/getliterature.tsp?genericPartNumber=sn65d... - -Required properties: -- compatible: Must be "ti,sn65dsi86" -- reg: i2c address of the chip, 0x2d as per datasheet -- enable-gpios: gpio specification for bridge_en pin (active high) - -- vccio-supply: A 1.8V supply that powers up the digital IOs. -- vpll-supply: A 1.8V supply that powers up the displayport PLL. -- vcca-supply: A 1.2V supply that powers up the analog circuits. -- vcc-supply: A 1.2V supply that powers up the digital core. - -Optional properties: -- interrupts-extended: Specifier for the SN65DSI86 interrupt line. - -- gpio-controller: Marks the device has a GPIO controller. -- #gpio-cells : Should be two. The first cell is the pin number and - the second cell is used to specify flags. - See ../../gpio/gpio.txt for more information. -- #pwm-cells : Should be one. See ../../pwm/pwm.yaml for description of - the cell formats. - -- clock-names: should be "refclk" -- clocks: Specification for input reference clock. The reference - clock rate must be 12 MHz, 19.2 MHz, 26 MHz, 27 MHz or 38.4 MHz. - -- data-lanes: See ../../media/video-interface.txt -- lane-polarities: See ../../media/video-interface.txt - -- suspend-gpios: specification for GPIO1 pin on bridge (active low) - -Required nodes: -This device has two video ports. Their connections are modelled using the -OF graph bindings specified in Documentation/devicetree/bindings/graph.txt. - -- Video port 0 for DSI input -- Video port 1 for eDP output - -Example -------- - -edp-bridge@2d { - compatible = "ti,sn65dsi86"; - #address-cells = <1>; - #size-cells = <0>; - reg = <0x2d>; - - enable-gpios = <&msmgpio 33 GPIO_ACTIVE_HIGH>; - suspend-gpios = <&msmgpio 34 GPIO_ACTIVE_LOW>; - - interrupts-extended = <&gpio3 4 IRQ_TYPE_EDGE_FALLING>; - - vccio-supply = <&pm8916_l17>; - vcca-supply = <&pm8916_l6>; - vpll-supply = <&pm8916_l17>; - vcc-supply = <&pm8916_l6>; - - clock-names = "refclk"; - clocks = <&input_refclk>; - - ports { - #address-cells = <1>; - #size-cells = <0>; - - port@0 { - reg = <0>; - - edp_bridge_in: endpoint { - remote-endpoint = <&dsi_out>; - }; - }; - - port@1 { - reg = <1>; - - edp_bridge_out: endpoint { - data-lanes = <2 1 3 0>; - lane-polarities = <0 1 0 1>; - remote-endpoint = <&edp_panel_in>; - }; - }; - }; -} diff --git a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml new file mode 100644 index 000000000000..6d7d40ad45ac --- /dev/null +++ b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml @@ -0,0 +1,279 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/display/bridge/ti,sn65dsi86.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: SN65DSI86 DSI to eDP bridge chip + +maintainers: + - Sandeep Panda spanda@codeaurora.org + +description: | + The Texas Instruments SN65DSI86 bridge takes MIPI DSI in and outputs eDP. + http://www.ti.com/general/docs/lit/getliterature.tsp?genericPartNumber=sn65d... + +properties: + compatible: + const: ti,sn65dsi86 + + reg: + const: 0x2d + + enable-gpios: + maxItems: 1 + description: GPIO specifier for bridge_en pin (active high). + + suspend-gpios: + maxItems: 1 + description: GPIO specifier for GPIO1 pin on bridge (active low). + + vccio-supply: + description: A 1.8V supply that powers the digital IOs. + + vpll-supply: + description: A 1.8V supply that powers the DisplayPort PLL. + + vcca-supply: + description: A 1.2V supply that powers the analog circuits. + + vcc-supply: + description: A 1.2V supply that powers the digital core. + + interrupts: + maxItems: 1 + + clocks: + maxItems: 1 + description: + Clock specifier for input reference clock. The reference clock rate must + be 12 MHz, 19.2 MHz, 26 MHz, 27 MHz or 38.4 MHz. + + clock-names: + const: refclk + + gpio-controller: true + '#gpio-cells': + const: 2 + description: + First cell is pin number, second cell is flags. GPIO pin numbers are + 1-based to match the datasheet. See ../../gpio/gpio.txt for more + information. + + '#pwm-cells': + const: 1 + description: See ../../pwm/pwm.yaml for description of the cell formats. + + ports: + type: object + + properties: + "#address-cells": + const: 1 + + "#size-cells": + const: 0 + + port@0: + type: object + additionalProperties: false + + description: + Video port for MIPI DSI input + + properties: + reg: + const: 0 + + endpoint: + type: object + additionalProperties: false + + properties: + remote-endpoint: true + + data-lanes: + minItems: 1 + maxItems: 4 + items: + enum: + - 0 + - 1 + - 2 + - 3 + description: See ../../media/video-interface.txt + + lane-polarities: + minItems: 1 + maxItems: 4 + items: + enum: + - 0 + - 1 + description: See ../../media/video-interface.txt + + dependencies: + data-lanes: [lane-polarities] + + required: + - reg + + port@1: + type: object + additionalProperties: false + + description: + Video port for eDP output (panel or connector). + + properties: + reg: + const: 1 + + endpoint: + type: object + additionalProperties: false + + properties: + remote-endpoint: true + + data-lanes: + minItems: 1 + maxItems: 4 + items: + enum: + - 0 + - 1 + - 2 + - 3 + description: See ../../media/video-interface.txt + + lane-polarities: + minItems: 1 + maxItems: 4 + items: + enum: + - 0 + - 1 + description: See ../../media/video-interface.txt + + dependencies: + data-lanes: [lane-polarities] + + required: + - reg + + required: + - "#address-cells" + - "#size-cells" + - port@0 + - port@1 + +required: + - compatible + - reg + - enable-gpios + - vccio-supply + - vpll-supply + - vcca-supply + - vcc-supply + - ports + +additionalProperties: false + +examples: + - | + #include <dt-bindings/clock/qcom,rpmh.h> + #include <dt-bindings/gpio/gpio.h> + #include <dt-bindings/interrupt-controller/irq.h> + + i2c { + #address-cells = <1>; + #size-cells = <0>; + + bridge@2d { + compatible = "ti,sn65dsi86"; + reg = <0x2d>; + + interrupt-parent = <&tlmm>; + interrupts = <10 IRQ_TYPE_LEVEL_HIGH>; + + enable-gpios = <&tlmm 102 GPIO_ACTIVE_HIGH>; + + vpll-supply = <&src_pp1800_s4a>; + vccio-supply = <&src_pp1800_s4a>; + vcca-supply = <&src_pp1200_l2a>; + vcc-supply = <&src_pp1200_l2a>; + + clocks = <&rpmhcc RPMH_LN_BB_CLK2>; + clock-names = "refclk"; + + ports { + #address-cells = <1>; + #size-cells = <0>; + + port@0 { + reg = <0>; + endpoint { + remote-endpoint = <&dsi0_out>; + }; + }; + + port@1 { + reg = <1>; + endpoint { + remote-endpoint = <&panel_in_edp>; + }; + }; + }; + }; + }; + - | + #include <dt-bindings/clock/qcom,rpmh.h> + #include <dt-bindings/gpio/gpio.h> + #include <dt-bindings/interrupt-controller/irq.h> + + i2c { + #address-cells = <1>; + #size-cells = <0>; + + bridge@2d { + compatible = "ti,sn65dsi86"; + reg = <0x2d>; + + enable-gpios = <&msmgpio 33 GPIO_ACTIVE_HIGH>; + suspend-gpios = <&msmgpio 34 GPIO_ACTIVE_LOW>; + + interrupts-extended = <&gpio3 4 IRQ_TYPE_EDGE_FALLING>; + + vccio-supply = <&pm8916_l17>; + vcca-supply = <&pm8916_l6>; + vpll-supply = <&pm8916_l17>; + vcc-supply = <&pm8916_l6>; + + clock-names = "refclk"; + clocks = <&input_refclk>; + + ports { + #address-cells = <1>; + #size-cells = <0>; + + port@0 { + reg = <0>; + + edp_bridge_in: endpoint { + remote-endpoint = <&dsi_out>; + }; + }; + + port@1 { + reg = <1>; + + edp_bridge_out: endpoint { + data-lanes = <2 1 3 0>; + lane-polarities = <0 1 0 1>; + remote-endpoint = <&edp_panel_in>; + }; + }; + }; + }; + };

The ti-sn65dsi86 MIPI DSI to eDP bridge chip has a dedicated hardware HPD (Hot Plug Detect) pin on it, but it's mostly useless for eDP because of excessive debouncing in hardware. Specifically there is no way to disable the debouncing and for eDP debouncing hurts you because HPD is just used for knowing when the panel is ready, not for detecting physical plug events.

Currently the driver in Linux just assumes that nobody has HPD hooked up. It relies on folks setting the "no-hpd" property in the panel node to specify that HPD isn't hooked up and then the panel driver using this to add some worst case delays when turning on the panel.

Apparently it's also useful to specify "no-hpd" in the bridge node so that the bridge driver can make sure it's doing the right thing without peeking into the panel [1]. This would be used if anyone ever found it useful to implement support for the HW HPD pin on the bridge. Let's add this property to the bindings.

NOTES: - This is somewhat of a backward-incompatible change. All current known users of ti-sn65dsi86 didn't have "no-hpd" specified in the bridge node yet none of them had HPD hooked up. This worked because the current Linux driver just assumed that HPD was never hooked up. We could make it less incompatible by saying that for this bridge it's assumed HPD isn't hooked up _unless_ a property is defined, but "no-hpd" is much more standard and it's unlikely to matter unless someone quickly goes and implements HPD in the driver. - It is sensible to specify "no-hpd" at the bridge chip level and specify "hpd-gpios" at the panel level. That would mean HPD is hooked up to some other GPIO in the system, just not the hardware HPD pin on the bridge chip.

[1] https://lore.kernel.org/r/20200417180819.GE5861@pendragon.ideasonboard.com

Signed-off-by: Douglas Anderson dianders@chromium.org Reviewed-by: Stephen Boyd swboyd@chromium.org ---

Changes in v3: - useful implement => useful to implement

Changes in v2: - ("dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd") new for v2.

.../devicetree/bindings/display/bridge/ti,sn65dsi86.yaml | 6 ++++++ 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml index 6d7d40ad45ac..5746416b0f73 100644 --- a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml +++ b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml @@ -28,6 +28,10 @@ properties: maxItems: 1 description: GPIO specifier for GPIO1 pin on bridge (active low).

+ no-hpd: + type: boolean + description: Set if the HPD line on the bridge isn't hooked up to anything. + vccio-supply: description: A 1.8V supply that powers the digital IOs.

@@ -207,6 +211,8 @@ examples: clocks = <&rpmhcc RPMH_LN_BB_CLK2>; clock-names = "refclk";

+ no-hpd; + ports { #address-cells = <1>; #size-cells = <0>;

We don't have the HPD line hooked up to the bridge chip. Add it as suggested in the patch ("dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd").

NOTE: this patch isn't expected to have any effect but just keeps us cleaner for the future. Currently the driver in Linux just assumes that nobody has HPD hooked up. This change allows us to later implement HPD support in the driver without messing up sdm845-cheza.

Signed-off-by: Douglas Anderson dianders@chromium.org Reviewed-by: Stephen Boyd swboyd@chromium.org ---

Changes in v3: None Changes in v2: - ("arm64: dts: sdm845: Add "no-hpd" to sn65dsi86 on cheza") new for v2.

arch/arm64/boot/dts/qcom/sdm845-cheza.dtsi | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sdm845-cheza.dtsi b/arch/arm64/boot/dts/qcom/sdm845-cheza.dtsi index 9070be43a309..5938f8b2aa2f 100644 --- a/arch/arm64/boot/dts/qcom/sdm845-cheza.dtsi +++ b/arch/arm64/boot/dts/qcom/sdm845-cheza.dtsi @@ -548,6 +548,8 @@ sn65dsi86_bridge: bridge@2d { clocks = <&rpmhcc RPMH_LN_BB_CLK2>; clock-names = "refclk";

+ no-hpd; + ports { #address-cells = <1>; #size-cells = <0>;