We want to be able to list an eDP panel as a child of an eDP controller node to represent the fact that the panel is connected to the controller's DP AUX bus. Though the panel and the controller are connected in several ways, the DP AUX bus is the primary control interface between the two and thus makes the most sense to model in device tree hierarchy.

Listing a panel in this way makes it possible for the panel driver to easily get access to the DP AUX bus that it resides on, which can be useful to help in auto-detecting the panel and for turning on various bits.

NOTE: historically eDP panels were _not_ listed under their controller but were listed at the top level of the device tree. This will still be supported for backward compatibility (and while DP controller drivers are adapted to support the new DT syntax) but should be considered deprecated since there is no downside to listing the panel under the controller.

For now, the DP AUX bus bindings will only support an eDP panel underneath. It's possible it could be extended to allow having a DP connector under it in the future.

NOTE: there is no "Example" in this bindings file. Yikes! This avoids duplicating the same example lots of places. See users of the aux bus (like ti-sn65dsi86) for examples.

The idea for this bus's design was hashed out over IRC [1].

[1] https://people.freedesktop.org/~cbrill/dri-log/?channel=dri-devel&date=2...

Signed-off-by: Douglas Anderson dianders@chromium.org Reviewed-by: Rob Herring robh@kernel.org ---

Changes in v9: - Commit message now notes aux-bus yaml won't have an "Example".

Changes in v8: - Separate DP AUX bus binding is new for v8.

.../bindings/display/dp-aux-bus.yaml | 37 +++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 Documentation/devicetree/bindings/display/dp-aux-bus.yaml

diff --git a/Documentation/devicetree/bindings/display/dp-aux-bus.yaml b/Documentation/devicetree/bindings/display/dp-aux-bus.yaml new file mode 100644 index 000000000000..5e4afe9f98fb --- /dev/null +++ b/Documentation/devicetree/bindings/display/dp-aux-bus.yaml @@ -0,0 +1,37 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/display/dp-aux-bus.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: DisplayPort AUX bus + +maintainers: + - Douglas Anderson dianders@chromium.org + +description: + DisplayPort controllers provide a control channel to the sinks that + are hooked up to them. This is the DP AUX bus. Over the DP AUX bus + we can query properties about a sink and also configure it. In + particular, DP sinks support DDC over DP AUX which allows tunneling + a standard I2C DDC connection over the AUX channel. + + To model this relationship, DP sinks should be placed as children + of the DP controller under the "aux-bus" node. + + At the moment, this binding only handles the eDP case. It is + possible it will be extended in the future to handle the DP case. + For DP, presumably a connector would be listed under the DP AUX + bus instead of a panel. + +properties: + $nodename: + const: "aux-bus" + + panel: + $ref: panel/panel-common.yaml# + +additionalProperties: false + +required: + - panel

The patch ("dt-bindings: drm: Introduce the DP AUX bus") talks about how using the DP AUX bus is better than learning how to slice bread. Let's add it to the ti-sn65dsi86 bindings.

Signed-off-by: Douglas Anderson dianders@chromium.org Reviewed-by: Rob Herring robh@kernel.org ---

Changes in v9: - Use an absolute path to refer to aux-bus schema.

Changes in v8: - ti-sn65dsi86 references the new aux bus bindings.

Changes in v7: - ti-sn65dsi86: Add aux-bus child patch new for v7.

.../bindings/display/bridge/ti,sn65dsi86.yaml | 20 ++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml index 26932d2e86ab..12b876a20574 100644 --- a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml +++ b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml @@ -70,6 +70,9 @@ properties: const: 1 description: See ../../pwm/pwm.yaml for description of the cell formats.

+ aux-bus: + $ref: /schemas/display/dp-aux-bus.yaml# + ports: $ref: /schemas/graph.yaml#/properties/ports

@@ -201,11 +204,26 @@ examples:

port@1 { reg = <1>; - endpoint { + sn65dsi86_out: endpoint { remote-endpoint = <&panel_in_edp>; }; }; }; + + aux-bus { + panel { + compatible = "boe,nv133fhm-n62"; + power-supply = <&pp3300_dx_edp>; + backlight = <&backlight>; + hpd-gpios = <&sn65dsi86_bridge 2 GPIO_ACTIVE_HIGH>; + + port { + panel_in_edp: endpoint { + remote-endpoint = <&sn65dsi86_out>; + }; + }; + }; + }; }; }; - |

Historically "simple" eDP panels have been handled by panel-simple which is a basic platform_device. In the device tree, the panel node was at the top level and not connected to anything else.

Let's change it so that, instead, panels can be represented as being children of the "DP AUX bus". Essentially we're saying that the hierarchy that we're going to represent is the "control" connections between devices. The DP AUX bus is a control bus provided by an eDP controller (the parent) and consumed by a device like a panel (the child).

The primary incentive here is to cleanly provide the panel driver the ability to communicate over the AUX bus while handling lifetime issues properly. The panel driver may want the AUX bus for controlling the backlight or querying the panel's EDID.

The idea for this bus's design was hashed out over IRC [1].

[1] https://people.freedesktop.org/~cbrill/dri-log/?channel=dri-devel&date=2...

Cc: Laurent Pinchart laurent.pinchart@ideasonboard.com Cc: Lyude Paul lyude@redhat.com Cc: Rajeev Nandan rajeevny@codeaurora.org Suggested-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Signed-off-by: Douglas Anderson dianders@chromium.org Acked-by: Linus Walleij linus.walleij@linaro.org --- There's a whole lot of boilerplate code here. I've tried my best to grok what all of it should be, drawing inspiration from other similar bus drivers (auxiliary, i2c, serdev, platform) and I've tried to test several of the corner cases, but I can't actually believe that I've touched every code path. Please yell if you see something dumb.

(no changes since v8)

Changes in v8: - Allow dp-aux-bus to be a module to fix allmodconfig builds

Changes in v7: - Patch introducing the DP AUX bus is new for v7.

drivers/gpu/drm/Kconfig | 5 + drivers/gpu/drm/Makefile | 2 + drivers/gpu/drm/drm_dp_aux_bus.c | 326 +++++++++++++++++++++++++++++++ include/drm/drm_dp_aux_bus.h | 57 ++++++ 4 files changed, 390 insertions(+) create mode 100644 drivers/gpu/drm/drm_dp_aux_bus.c create mode 100644 include/drm/drm_dp_aux_bus.h

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index 7ff89690a976..1366d8d4610a 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -35,6 +35,11 @@ config DRM_MIPI_DSI bool depends on DRM

+config DRM_DP_AUX_BUS + tristate + depends on DRM + depends on OF + config DRM_DP_AUX_CHARDEV bool "DRM DP AUX Interface" depends on DRM diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index a118692a6df7..12e6f4e485ed 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -33,6 +33,8 @@ drm-$(CONFIG_PCI) += drm_pci.o drm-$(CONFIG_DEBUG_FS) += drm_debugfs.o drm_debugfs_crc.o drm-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o

+obj-$(CONFIG_DRM_DP_AUX_BUS) += drm_dp_aux_bus.o + drm_vram_helper-y := drm_gem_vram_helper.o obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o

diff --git a/drivers/gpu/drm/drm_dp_aux_bus.c b/drivers/gpu/drm/drm_dp_aux_bus.c new file mode 100644 index 000000000000..d0e44de287d4 --- /dev/null +++ b/drivers/gpu/drm/drm_dp_aux_bus.c @@ -0,0 +1,326 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright 2021 Google Inc. + * + * The DP AUX bus is used for devices that are connected over a DisplayPort + * AUX bus. The devices on the far side of the bus are referred to as + * endpoints in this code. + * + * Commonly there is only one device connected to the DP AUX bus: a panel. + * Though historically panels (even DP panels) have been modeled as simple + * platform devices, putting them under the DP AUX bus allows the panel driver + * to perform transactions on that bus. + */ + +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of_device.h> +#include <linux/pm_domain.h> +#include <linux/pm_runtime.h> + +#include <drm/drm_dp_aux_bus.h> +#include <drm/drm_dp_helper.h> + + +/** + * dp_aux_ep_match() - The match function for the dp_aux_bus. + * @dev: The device to match. + * @drv: The driver to try to match against. + * + * At the moment, we just match on device tree. + * + * Return: True if this driver matches this device; false otherwise. + */ +static int dp_aux_ep_match(struct device *dev, struct device_driver *drv) +{ + return !!of_match_device(drv->of_match_table, dev); +} + +/** + * dp_aux_ep_probe() - The probe function for the dp_aux_bus. + * @dev: The device to probe. + * + * Calls through to the endpoint driver probe. + * + * Return: 0 if no error or negative error code. + */ +static int dp_aux_ep_probe(struct device *dev) +{ + struct dp_aux_ep_driver *aux_ep_drv = to_dp_aux_ep_drv(dev->driver); + struct dp_aux_ep_device *aux_ep = to_dp_aux_ep_dev(dev); + int ret; + + ret = dev_pm_domain_attach(dev, true); + if (ret) + return dev_err_probe(dev, ret, "Failed to attach to PM Domain\n"); + + ret = aux_ep_drv->probe(aux_ep); + if (ret) + dev_pm_domain_detach(dev, true); + + return ret; +} + +/** + * dp_aux_ep_remove() - The remove function for the dp_aux_bus. + * @dev: The device to remove. + * + * Calls through to the endpoint driver remove. + * + * Return: 0 if no error or negative error code. + */ +static int dp_aux_ep_remove(struct device *dev) +{ + struct dp_aux_ep_driver *aux_ep_drv = to_dp_aux_ep_drv(dev->driver); + struct dp_aux_ep_device *aux_ep = to_dp_aux_ep_dev(dev); + + if (aux_ep_drv->remove) + aux_ep_drv->remove(aux_ep); + dev_pm_domain_detach(dev, true); + + return 0; +} + +/** + * dp_aux_ep_shutdown() - The shutdown function for the dp_aux_bus. + * @dev: The device to shutdown. + * + * Calls through to the endpoint driver shutdown. + */ +static void dp_aux_ep_shutdown(struct device *dev) +{ + struct dp_aux_ep_driver *aux_ep_drv; + + if (!dev->driver) + return; + + aux_ep_drv = to_dp_aux_ep_drv(dev->driver); + if (aux_ep_drv->shutdown) + aux_ep_drv->shutdown(to_dp_aux_ep_dev(dev)); +} + +static struct bus_type dp_aux_bus_type = { + .name = "dp-aux", + .match = dp_aux_ep_match, + .probe = dp_aux_ep_probe, + .remove = dp_aux_ep_remove, + .shutdown = dp_aux_ep_shutdown, +}; + +static ssize_t modalias_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return of_device_modalias(dev, buf, PAGE_SIZE); +} +static DEVICE_ATTR_RO(modalias); + +static struct attribute *dp_aux_ep_dev_attrs[] = { + &dev_attr_modalias.attr, + NULL, +}; +ATTRIBUTE_GROUPS(dp_aux_ep_dev); + +/** + * dp_aux_ep_dev_release() - Free memory for the dp_aux_ep device + * @dev: The device to free. + * + * Return: 0 if no error or negative error code. + */ +static void dp_aux_ep_dev_release(struct device *dev) +{ + kfree(to_dp_aux_ep_dev(dev)); +} + +static struct device_type dp_aux_device_type_type = { + .groups = dp_aux_ep_dev_groups, + .uevent = of_device_uevent_modalias, + .release = dp_aux_ep_dev_release, +}; + +/** + * of_dp_aux_ep_destroy() - Destroy an DP AUX endpoint device + * @dev: The device to destroy. + * @data: Not used + * + * This is just used as a callback by of_dp_aux_depopulate_ep_devices() and + * is called for _all_ of the child devices of the device providing the AUX bus. + * We'll only act on those that are of type "dp_aux_bus_type". + * + * This function is effectively an inverse of what's in the loop + * in of_dp_aux_populate_ep_devices(). + * + * Return: 0 if no error or negative error code. + */ +static int of_dp_aux_ep_destroy(struct device *dev, void *data) +{ + struct device_node *np = dev->of_node; + + if (dev->bus != &dp_aux_bus_type) + return 0; + + if (!of_node_check_flag(np, OF_POPULATED)) + return 0; + + of_node_clear_flag(np, OF_POPULATED); + of_node_put(np); + + device_unregister(dev); + + return 0; +} + +/** + * of_dp_aux_depopulate_ep_devices() - Undo of_dp_aux_populate_ep_devices + * @aux: The AUX channel whose devices we want to depopulate + * + * This will destroy all devices that were created + * by of_dp_aux_populate_ep_devices(). + */ +void of_dp_aux_depopulate_ep_devices(struct drm_dp_aux *aux) +{ + device_for_each_child_reverse(aux->dev, NULL, of_dp_aux_ep_destroy); +} +EXPORT_SYMBOL_GPL(of_dp_aux_depopulate_ep_devices); + +/** + * of_dp_aux_populate_ep_devices() - Populate the endpoint devices on the DP AUX + * @aux: The AUX channel whose devices we want to populate. It is required that + * drm_dp_aux_init() has already been called for this AUX channel. + * + * This will populate all the devices under the "aux-bus" node of the device + * providing the AUX channel (AKA aux->dev). + * + * When this function finishes, it is _possible_ (but not guaranteed) that + * our sub-devices will have finished probing. It should be noted that if our + * sub-devices return -EPROBE_DEFER that we will not return any error codes + * ourselves but our sub-devices will _not_ have actually probed successfully + * yet. There may be other cases (maybe added in the future?) where sub-devices + * won't have been probed yet when this function returns, so it's best not to + * rely on that. + * + * If this function succeeds you should later make sure you call + * of_dp_aux_depopulate_ep_devices() to undo it, or just use the devm version + * of this function. + * + * Return: 0 if no error or negative error code. + */ +int of_dp_aux_populate_ep_devices(struct drm_dp_aux *aux) +{ + struct device_node *bus, *np; + struct dp_aux_ep_device *aux_ep; + int ret; + + /* drm_dp_aux_init() should have been called already; warn if not */ + WARN_ON_ONCE(!aux->ddc.algo); + + if (!aux->dev->of_node) + return 0; + + bus = of_get_child_by_name(aux->dev->of_node, "aux-bus"); + if (!bus) + return 0; + + for_each_available_child_of_node(bus, np) { + if (of_node_test_and_set_flag(np, OF_POPULATED)) + continue; + + aux_ep = kzalloc(sizeof(*aux_ep), GFP_KERNEL); + aux_ep->aux = aux; + + aux_ep->dev.parent = aux->dev; + aux_ep->dev.bus = &dp_aux_bus_type; + aux_ep->dev.type = &dp_aux_device_type_type; + aux_ep->dev.of_node = of_node_get(np); + dev_set_name(&aux_ep->dev, "aux-%s", dev_name(aux->dev)); + + ret = device_register(&aux_ep->dev); + if (ret) { + dev_err(aux->dev, "Failed to create AUX EP for %pOF: %d\n", np, ret); + of_node_clear_flag(np, OF_POPULATED); + of_node_put(np); + + /* + * As per docs of device_register(), call this instead + * of kfree() directly for error cases. + */ + put_device(&aux_ep->dev); + + /* + * Following in the footsteps of of_i2c_register_devices(), + * we won't fail the whole function here--we'll just + * continue registering any other devices we find. + */ + } + } + + of_node_put(bus); + + return 0; +} + +static void of_dp_aux_depopulate_ep_devices_void(void *data) +{ + of_dp_aux_depopulate_ep_devices(data); +} + +/** + * devm_of_dp_aux_populate_ep_devices() - devm wrapper for of_dp_aux_populate_ep_devices() + * @aux: The AUX channel whose devices we want to populate + * + * Handles freeing w/ devm on the device "aux->dev". + * + * Return: 0 if no error or negative error code. + */ +int devm_of_dp_aux_populate_ep_devices(struct drm_dp_aux *aux) +{ + int ret; + + ret = of_dp_aux_populate_ep_devices(aux); + if (ret) + return ret; + + return devm_add_action_or_reset(aux->dev, + of_dp_aux_depopulate_ep_devices_void, + aux); +} +EXPORT_SYMBOL_GPL(devm_of_dp_aux_populate_ep_devices); + +int __dp_aux_dp_driver_register(struct dp_aux_ep_driver *drv, struct module *owner) +{ + drv->driver.owner = owner; + drv->driver.bus = &dp_aux_bus_type; + + return driver_register(&drv->driver); + +} +EXPORT_SYMBOL_GPL(__dp_aux_dp_driver_register); + +void dp_aux_dp_driver_unregister(struct dp_aux_ep_driver *drv) +{ + driver_unregister(&drv->driver); +} +EXPORT_SYMBOL_GPL(dp_aux_dp_driver_unregister); + +static int __init dp_aux_bus_init(void) +{ + int ret; + + ret = bus_register(&dp_aux_bus_type); + if (ret) + return ret; + + return 0; +} + +static void __exit dp_aux_bus_exit(void) +{ + bus_unregister(&dp_aux_bus_type); +} + +subsys_initcall(dp_aux_bus_init); +module_exit(dp_aux_bus_exit); + +MODULE_AUTHOR("Douglas Anderson dianders@chromium.org"); +MODULE_DESCRIPTION("DRM DisplayPort AUX bus"); +MODULE_LICENSE("GPL v2"); diff --git a/include/drm/drm_dp_aux_bus.h b/include/drm/drm_dp_aux_bus.h new file mode 100644 index 000000000000..4f19b20b1dd6 --- /dev/null +++ b/include/drm/drm_dp_aux_bus.h @@ -0,0 +1,57 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright 2021 Google Inc. + * + * The DP AUX bus is used for devices that are connected over a DisplayPort + * AUX bus. The devices on the far side of the bus are referred to as + * endpoints in this code. + */ + +#ifndef _DP_AUX_BUS_H_ +#define _DP_AUX_BUS_H_ + +#include <linux/device.h> +#include <linux/mod_devicetable.h> + +/** + * struct dp_aux_ep_device - Main dev structure for DP AUX endpoints + * + * This is used to instantiate devices that are connected via a DP AUX + * bus. Usually the device is a panel, but conceivable other devices could + * be hooked up there. + */ +struct dp_aux_ep_device { + /** @dev: The normal dev pointer */ + struct device dev; + /** @aux: Pointer to the aux bus */ + struct drm_dp_aux *aux; +}; + +struct dp_aux_ep_driver { + int (*probe)(struct dp_aux_ep_device *aux_ep); + void (*remove)(struct dp_aux_ep_device *aux_ep); + void (*shutdown)(struct dp_aux_ep_device *aux_ep); + struct device_driver driver; +}; + +static inline struct dp_aux_ep_device *to_dp_aux_ep_dev(struct device *dev) +{ + return container_of(dev, struct dp_aux_ep_device, dev); +} + +static inline struct dp_aux_ep_driver *to_dp_aux_ep_drv(struct device_driver *drv) +{ + return container_of(drv, struct dp_aux_ep_driver, driver); +} + +int of_dp_aux_populate_ep_devices(struct drm_dp_aux *aux); +void of_dp_aux_depopulate_ep_devices(struct drm_dp_aux *aux); +int devm_of_dp_aux_populate_ep_devices(struct drm_dp_aux *aux); + +#define dp_aux_dp_driver_register(aux_ep_drv) \ + __dp_aux_dp_driver_register(aux_ep_drv, THIS_MODULE) +int __dp_aux_dp_driver_register(struct dp_aux_ep_driver *aux_ep_drv, + struct module *owner); +void dp_aux_dp_driver_unregister(struct dp_aux_ep_driver *aux_ep_drv); + +#endif /* _DP_AUX_BUS_H_ */

The panel-simple driver can already have devices instantiated as platform devices or MIPI DSI devices. Let's add a 3rd way to instantiate it: as DP AUX endpoint devices.

At the moment there is no benefit to instantiating it in this way, but: - In the next patch we'll give it access to the DDC channel via the DP AUX bus. - Possibly in the future we may use this channel to configure the backlight.

Signed-off-by: Douglas Anderson dianders@chromium.org Reviewed-by: Lyude Paul lyude@redhat.com ---

(no changes since v7)

Changes in v7: - Patch to allow panel-simple to be DP AUX EP new for v7.

drivers/gpu/drm/panel/Kconfig | 1 + drivers/gpu/drm/panel/panel-simple.c | 52 +++++++++++++++++++++++++--- 2 files changed, 49 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig index ef87d92cdf49..b1ea86d9fdaf 100644 --- a/drivers/gpu/drm/panel/Kconfig +++ b/drivers/gpu/drm/panel/Kconfig @@ -82,6 +82,7 @@ config DRM_PANEL_SIMPLE depends on BACKLIGHT_CLASS_DEVICE depends on PM select VIDEOMODE_HELPERS + select DRM_DP_AUX_BUS help DRM panel driver for dumb panels that need at most a regulator and a GPIO to be powered up. Optionally a backlight can be attached so diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c index 21939d4352cf..d3b5ae22d939 100644 --- a/drivers/gpu/drm/panel/panel-simple.c +++ b/drivers/gpu/drm/panel/panel-simple.c @@ -36,6 +36,7 @@

#include <drm/drm_crtc.h> #include <drm/drm_device.h> +#include <drm/drm_dp_aux_bus.h> #include <drm/drm_mipi_dsi.h> #include <drm/drm_panel.h>

@@ -4957,6 +4958,38 @@ static struct mipi_dsi_driver panel_simple_dsi_driver = { .shutdown = panel_simple_dsi_shutdown, };

+static int panel_simple_dp_aux_ep_probe(struct dp_aux_ep_device *aux_ep) +{ + const struct of_device_id *id; + + id = of_match_node(platform_of_match, aux_ep->dev.of_node); + if (!id) + return -ENODEV; + + return panel_simple_probe(&aux_ep->dev, id->data); +} + +static void panel_simple_dp_aux_ep_remove(struct dp_aux_ep_device *aux_ep) +{ + panel_simple_remove(&aux_ep->dev); +} + +static void panel_simple_dp_aux_ep_shutdown(struct dp_aux_ep_device *aux_ep) +{ + panel_simple_shutdown(&aux_ep->dev); +} + +static struct dp_aux_ep_driver panel_simple_dp_aux_ep_driver = { + .driver = { + .name = "panel-simple-dp-aux", + .of_match_table = platform_of_match, /* Same as platform one! */ + .pm = &panel_simple_pm_ops, + }, + .probe = panel_simple_dp_aux_ep_probe, + .remove = panel_simple_dp_aux_ep_remove, + .shutdown = panel_simple_dp_aux_ep_shutdown, +}; + static int __init panel_simple_init(void) { int err; @@ -4965,15 +4998,25 @@ static int __init panel_simple_init(void) if (err < 0) return err;

+ err = dp_aux_dp_driver_register(&panel_simple_dp_aux_ep_driver); + if (err < 0) + goto err_did_platform_register; + if (IS_ENABLED(CONFIG_DRM_MIPI_DSI)) { err = mipi_dsi_driver_register(&panel_simple_dsi_driver); - if (err < 0) { - platform_driver_unregister(&panel_simple_platform_driver); - return err; - } + if (err < 0) + goto err_did_aux_ep_register; }

return 0; + +err_did_aux_ep_register: + dp_aux_dp_driver_unregister(&panel_simple_dp_aux_ep_driver); + +err_did_platform_register: + platform_driver_unregister(&panel_simple_platform_driver); + + return err; } module_init(panel_simple_init);

@@ -4982,6 +5025,7 @@ static void __exit panel_simple_exit(void) if (IS_ENABLED(CONFIG_DRM_MIPI_DSI)) mipi_dsi_driver_unregister(&panel_simple_dsi_driver);

+ dp_aux_dp_driver_unregister(&panel_simple_dp_aux_ep_driver); platform_driver_unregister(&panel_simple_platform_driver); } module_exit(panel_simple_exit);

This is really just a revert of commit 58074b08c04a ("drm/bridge: ti-sn65dsi86: Read EDID blob over DDC"), resolving conflicts.

The old code failed to read the EDID properly in a very important case: before the bridge's pre_enable() was called. The way things need to work: 1. Read the EDID. 2. Based on the EDID, decide on video settings and pixel clock. 3. Enable the bridge w/ the desired settings.

The way things were working: 1. Try to read the EDID but fail; fall back to hardcoded values. 2. Based on hardcoded values, decide on video settings and pixel clock. 3. Enable the bridge w/ the desired settings. 4. Try again to read the EDID, it works now! 5. Realize that the hardcoded settings weren't quite right. 6. Disable / reenable the bridge w/ the right settings.

The reasons for the failures were twofold: a) Since we never ran the bridge chip's pre-enable then we never set the bit to ignore HPD. This meant the bridge chip didn't even _try_ to go out on the bus and communicate with the panel. b) Even if we fixed things to ignore HPD, the EDID still wouldn't read if the panel wasn't on.

Instead of reverting the code, we could fix it to set the HPD bit and also power on the panel. However, it also works nicely to just let the panel code read the EDID. Now that we've split the driver up we can expose the DDC AUX channel bus to the panel node. The panel can take charge of reading the EDID.

NOTE: in order for things to work, anyone that needs to read the EDID will need to instantiate their panel using the new DP AUX bus (AKA by listing their panel under the "aux-bus" node of the bridge chip in the device tree).

In the future if we want to use the bridge chip to provide a full external DP port (which won't have a panel) then we will have to conditinally add EDID reading back in.

Suggested-by: Andrzej Hajda a.hajda@samsung.com Signed-off-by: Douglas Anderson dianders@chromium.org Reviewed-by: Bjorn Andersson bjorn.andersson@linaro.org ---

(no changes since v7)

Changes in v7: - Adjusted commit message to talk about DP AUX bus.

drivers/gpu/drm/bridge/ti-sn65dsi86.c | 22 ---------------------- 1 file changed, 22 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c index 32bd35c98d95..b544cbce7fdd 100644 --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c @@ -126,7 +126,6 @@ * @connector: Our connector. * @host_node: Remote DSI node. * @dsi: Our MIPI DSI source. - * @edid: Detected EDID of eDP panel. * @refclk: Our reference clock. * @panel: Our panel. * @enable_gpio: The GPIO we toggle to enable the bridge. @@ -157,7 +156,6 @@ struct ti_sn65dsi86 { struct drm_dp_aux aux; struct drm_bridge bridge; struct drm_connector connector; - struct edid *edid; struct device_node *host_node; struct mipi_dsi_device *dsi; struct clk *refclk; @@ -406,24 +404,6 @@ connector_to_ti_sn65dsi86(struct drm_connector *connector) static int ti_sn_bridge_connector_get_modes(struct drm_connector *connector) { struct ti_sn65dsi86 *pdata = connector_to_ti_sn65dsi86(connector); - struct edid *edid = pdata->edid; - int num, ret; - - if (!edid) { - pm_runtime_get_sync(pdata->dev); - edid = pdata->edid = drm_get_edid(connector, &pdata->aux.ddc); - pm_runtime_put_autosuspend(pdata->dev); - } - - if (edid && drm_edid_is_valid(edid)) { - ret = drm_connector_update_edid_property(connector, edid); - if (!ret) { - num = drm_add_edid_modes(connector, edid); - if (num) - return num; - } - } - return drm_panel_get_modes(pdata->panel, connector); }

@@ -1356,8 +1336,6 @@ static void ti_sn_bridge_remove(struct auxiliary_device *adev) mipi_dsi_device_unregister(pdata->dsi); }

- kfree(pdata->edid); - drm_bridge_remove(&pdata->bridge);

of_node_put(pdata->host_node);