Hi,

On Mon, Sep 13, 2021 at 2:33 PM Philip Chen philipchen@chromium.org wrote:

Implement the first version of AUX support, which will be useful as we expand the driver to support varied use cases.

WARNING: This patch is not fully verified by hardware. But as AUX CH is not implemented for ps8640 driver until now, the patch shouldn't cause any functional regression in practice.

Thanks for the heads up. NOTE: having this patch posted to do early code review is fine, but fair warning that I don't think there'd be much benefit in landing until the patch is verified more.

Signed-off-by: Philip Chen philipchen@chromium.org

Changes in v2:

• Handle the case where an AUX transaction has no payload
• Add a reg polling for p0.0x83 to confirm AUX cmd is issued and read data is returned
• Replace regmap_noinc_read/write with looped regmap_read/write, as regmap_noinc_read/write doesn't read one byte at a time unless max_raw_read/write is set to 1.

What about if you set val_bytes? I think you just need to set that to "1" and it'll work?

• Register/Unregister the AUX device explicitly when the bridge is attached/detached
• Remove the use of runtime PM

I suspect runtime PM will need to be added back in at some point since AUX channel needs to be functional even if the bridge hasn't been "pre_enable"ed.

• Program AUX addr/cmd/len in a single regmap_bulk_write()
• Add newlines for DRM_ERROR mesages

drivers/gpu/drm/bridge/parade-ps8640.c | 156 ++++++++++++++++++++++++- 1 file changed, 153 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c index 1b2414601538..3b28e992bb3e 100644 --- a/drivers/gpu/drm/bridge/parade-ps8640.c +++ b/drivers/gpu/drm/bridge/parade-ps8640.c @@ -13,11 +13,32 @@ #include <linux/regulator/consumer.h>

#include <drm/drm_bridge.h> +#include <drm/drm_dp_helper.h> #include <drm/drm_mipi_dsi.h> #include <drm/drm_of.h> #include <drm/drm_panel.h> #include <drm/drm_print.h>

+#define PAGE0_AUXCH_CFG3 0x76 +#define AUXCH_CFG3_RESET 0xff +#define PAGE0_AUX_ADDR_7_0 0x7d +#define PAGE0_AUX_ADDR_15_8 0x7e +#define PAGE0_AUX_ADDR_23_16 0x7f

nit: my manual calls the above "SWAUX_ADDR". Can you add the "SW"? I know it doesn't look pretty, but matching the manual is really nice. Similar with other commands below.

+#define AUX_ADDR_19_16_MASK GENMASK(3, 0) +#define AUX_CMD_MASK GENMASK(7, 4) +#define PAGE0_AUX_LENGTH 0x80 +#define AUX_LENGTH_MASK GENMASK(3, 0) +#define AUX_NO_PAYLOAD BIT(7) +#define PAGE0_AUX_WDATA 0x81 +#define PAGE0_AUX_RDATA 0x82 +#define PAGE0_AUX_CTRL 0x83 +#define AUX_SEND BIT(0) +#define PAGE0_AUX_STATUS 0x84 +#define AUX_STATUS_MASK GENMASK(7, 5) +#define AUX_STATUS_TIMEOUT (0x7 << 5) +#define AUX_STATUS_DEFER (0x2 << 5) +#define AUX_STATUS_NACK (0x1 << 5)

#define PAGE2_GPIO_H 0xa7 #define PS_GPIO9 BIT(1) #define PAGE2_I2C_BYPASS 0xea @@ -68,6 +89,7 @@ enum ps8640_vdo_control { struct ps8640 { struct drm_bridge bridge; struct drm_bridge *panel_bridge;

•   struct drm_dp_aux aux;
    struct mipi_dsi_device *dsi;
    struct i2c_client *page[MAX_DEVS];
    struct regmap   *regmap[MAX_DEVS];
  

@@ -117,6 +139,114 @@ static inline struct ps8640 *bridge_to_ps8640(struct drm_bridge *e) return container_of(e, struct ps8640, bridge); }

+static inline struct ps8640 *aux_to_ps8640(struct drm_dp_aux *aux) +{

•   return container_of(aux, struct ps8640, aux);
  

+}

+static ssize_t ps8640_aux_transfer(struct drm_dp_aux *aux,

•                              struct drm_dp_aux_msg *msg)
  

+{

•   struct ps8640 *ps_bridge = aux_to_ps8640(aux);
  

•   struct regmap *map = ps_bridge->regmap[PAGE0_DP_CNTL];
  

•   unsigned int len = msg->size;
  

•   unsigned int data;
  

•   int ret;
  

•   u8 request = msg->request &
  

•                ~(DP_AUX_I2C_MOT | DP_AUX_I2C_WRITE_STATUS_UPDATE);
  

•   u8 *buf = msg->buffer;
  

•   u8 addr_len[PAGE0_AUX_LENGTH + 1 - PAGE0_AUX_ADDR_7_0];
  

•   u8 i;
  

•   bool is_native_aux = false;
  

•   if (len > DP_AUX_MAX_PAYLOAD_BYTES)
  

•           return -EINVAL;
  

•   switch (request) {
  

•   case DP_AUX_NATIVE_WRITE:
  

•   case DP_AUX_NATIVE_READ:
  

•           is_native_aux = true;
  

I think you need a "fallthrough;" here.

•   case DP_AUX_I2C_WRITE:
  

•   case DP_AUX_I2C_READ:
  

•           ret = regmap_write(map, PAGE0_AUXCH_CFG3, AUXCH_CFG3_RESET);
  

Why not move the regmap_write() out of the switch statement? Also: you store the "ret" but you never check it. You should handle the error.

•           break;
  

•   default:
  

•           ret = -EINVAL;
  

•           goto exit;
  

•   }
  

•   /* Assume it's good */
  

•   msg->reply = 0;
  

•   addr_len[0] = msg->address & 0xff;
  

•   addr_len[1] = (msg->address >> 8) & 0xff;
  

•   addr_len[2] = ((request << 4) & AUX_CMD_MASK) |
  

Instead of "request", needs to be the version of "request" without DP_AUX_I2C_MOT and DP_AUX_I2C_WRITE_STATUS_UPDATE stripped out. In the TI bridge chip it calls this "request_val".

•           ((msg->address >> 16) & AUX_ADDR_19_16_MASK);
  

•   addr_len[3] = (len == 0) ? AUX_NO_PAYLOAD :
  

•                   ((len - 1) & AUX_LENGTH_MASK);
  

•   regmap_bulk_write(map, PAGE0_AUX_ADDR_7_0, addr_len,
  

•                     ARRAY_SIZE(addr_len));
  

•   if (len && (request == DP_AUX_NATIVE_WRITE ||
  

•               request == DP_AUX_I2C_WRITE)) {
  

•           /* Write to the internal FIFO buffer */
  

•           for (i = 0; i < len; i++) {
  

•                   ret = regmap_write(map, PAGE0_AUX_WDATA, buf[i]);
  

•                   if (ret < 0) {
  

•                           DRM_ERROR("failed to write PAGE0_AUX_WDATA\n");
  

nit: can you use dev_err() so that the dev gets printed? Also, can you print the error code?

•                           goto exit;
  

Unless you re-add pm_runtime (which you'll have to eventually), the above "goto exit" should just be "return ret". Same with other "goto exit"s in your patch.

•                   }
  

•           }
  

•   }
  

•   regmap_write(map, PAGE0_AUX_CTRL, AUX_SEND);
  

•   /* Zero delay loop because i2c transactions are slow already */
  

•   ret = regmap_read_poll_timeout(map, PAGE0_AUX_CTRL, data,
  

•                                  !(data & AUX_SEND), 0, 50 * 1000);
  

•   if (ret)
  

•           goto exit;
  

•   regmap_read(map, PAGE0_AUX_STATUS, &data);
  

•   switch (data & AUX_STATUS_MASK) {
  

•   case AUX_STATUS_DEFER:
  

•           if (is_native_aux)
  

•                   msg->reply |= DP_AUX_NATIVE_REPLY_DEFER;
  

•           else
  

•                   msg->reply |= DP_AUX_I2C_REPLY_DEFER;
  

•           ret = -EBUSY;
  

•           goto exit;
  

In the TI bridge chip driver we decided that we shouldn't handle the defer case since the hardware was already handling it. Specifically in the case of this bridge you can see that AUXCH_CFG1 shows a default value of retrying 7 times. ...so presumably we shouldn't ever actually get a defer here.

•   case AUX_STATUS_NACK:
  

•           if (is_native_aux)
  

•                   msg->reply |= DP_AUX_NATIVE_REPLY_NACK;
  

•           else
  

•                   msg->reply |= DP_AUX_I2C_REPLY_NACK;
  

•           ret = -EBUSY;
  

I believe that you shouldn't be setting "ret = -EBUSY" here. You're supposed to be returning the number of bytes that were read / written before the NAK happened. In the read case you should also be returning the data that was actually read before the NAK too. Basically, add something that reads "M" and stores it in "len"

•           goto exit;
  

•   case AUX_STATUS_TIMEOUT:
  

•           ret = -ETIMEDOUT;
  

•           goto exit;
  

You seem to be missing handlers for: * ACKM * Invalid reply * I2C NACK * I2C defer (probably don't need to deal with this?)

•   }
  

•   if (len && (request == DP_AUX_NATIVE_READ ||
  

•               request == DP_AUX_I2C_READ)) {
  

•           /* Read from the internal FIFO buffer */
  

•           for (i = 0; i < len; i++) {
  

•                   ret = regmap_read(map, PAGE0_AUX_WDATA, &data);
  

Oops, the above should be RDATA, not WDATA.

•                   buf[i] = data;
  

•                   if (ret < 0)
  

•                           DRM_ERROR("failed to read PAGE0_AUX_RDATA\n");
  

Return the error? Print the error code?

•           }
  

•   }
  

+exit:

•   if (ret)
  

•           return ret;
  

•   return len;
  

+}

static int ps8640_bridge_vdo_control(struct ps8640 *ps_bridge, const enum ps8640_vdo_control ctrl) { @@ -286,18 +416,32 @@ static int ps8640_bridge_attach(struct drm_bridge *bridge, dsi->format = MIPI_DSI_FMT_RGB888; dsi->lanes = NUM_MIPI_LANES; ret = mipi_dsi_attach(dsi);

•   if (ret)
  

•           goto err_dsi_attach;
  

•   if (ret) {
  

•           dev_err(dev, "failed to attach dsi device: %d\n", ret);
  

•           goto exit;
  

•   }
  

•   ret = drm_dp_aux_register(&ps_bridge->aux);
  

•   if (ret) {
  

•           dev_err(dev, "failed to register DP AUX channel: %d\n", ret);
  

•           goto exit;
  

Don't you need to go to an "error" label that causes mipi_dsi_detach() to get called?

•   }
  
    /* Attach the panel-bridge to the dsi bridge */
    return drm_bridge_attach(bridge->encoder, ps_bridge->panel_bridge,
                             &ps_bridge->bridge, flags);
  
  

-err_dsi_attach: +exit: mipi_dsi_device_unregister(dsi); return ret; }

+static void ps8640_bridge_detach(struct drm_bridge *bridge) +{

•   drm_dp_aux_unregister(&bridge_to_ps8640(bridge)->aux);
  

I suspect that the lack of a "detach" was a prexisting bug. Perhaps you can submit a patch before yours that fixes it? It should undo the things that attach did, like calling mipi_dsi_detach() and mipi_dsi_device_unregister()

+}

static struct edid *ps8640_bridge_get_edid(struct drm_bridge *bridge, struct drm_connector *connector) { @@ -334,6 +478,7 @@ static struct edid *ps8640_bridge_get_edid(struct drm_bridge *bridge,

static const struct drm_bridge_funcs ps8640_bridge_funcs = { .attach = ps8640_bridge_attach,

•   .detach = ps8640_bridge_detach,
    .get_edid = ps8640_bridge_get_edid,
    .post_disable = ps8640_post_disable,
    .pre_enable = ps8640_pre_enable,
  

@@ -412,6 +557,11 @@ static int ps8640_probe(struct i2c_client *client)

    i2c_set_clientdata(client, ps_bridge);

•   ps_bridge->aux.name = "parade-ps8640-aux";
  

•   ps_bridge->aux.dev = dev;
  

•   ps_bridge->aux.transfer = ps8640_aux_transfer;
  

•   drm_dp_aux_init(&ps_bridge->aux);
  

Eventually you're going to want these here:

devm_of_dp_aux_populate_ep_devices(&ps_bridge->aux); wait_for_device_probe()

...which I believe will enable DP AUX bus support. The second of those two is just me being paranoid to handle the case where the AUX endpoint device has an async probe.

In order to make the above work you'll need proper pm_runtime support though since the aux channel needs to be usable before pre_enable(). That means you'll have to power the bridge on in the pm_runtime code (enough to talk over the aux channel) and you'll need to use "autosuspend" so that the bridge doesn't constantly power down between aux transactions.

-Doug

Hi, Doug

Thanks for the review. I fixed the nits you pointed out in v3. PTAL.

On Mon, Sep 13, 2021 at 5:32 PM Doug Anderson dianders@chromium.org wrote:

Hi,

On Mon, Sep 13, 2021 at 2:33 PM Philip Chen philipchen@chromium.org wrote:

...

diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c index 685e9c38b2db..1b2414601538 100644 --- a/drivers/gpu/drm/bridge/parade-ps8640.c +++ b/drivers/gpu/drm/bridge/parade-ps8640.c @@ -9,6 +9,7 @@ #include <linux/i2c.h> #include <linux/module.h> #include <linux/of_graph.h> +#include <linux/regmap.h> #include <linux/regulator/consumer.h>

#include <drm/drm_bridge.h> @@ -31,6 +32,11 @@

#define NUM_MIPI_LANES 4

+#define COMMON_PS8640_REGMAP_CONFIG \

•   .reg_bits = 8, \
  

•   .val_bits = 8, \
  

•   .cache_type = REGCACHE_NONE
  

At some point we should see if we get any speed gains by actually caching, but that could be done later and isn't terribly high priority.

...

/*

• PS8640 uses multiple addresses:
• page[0]: for DP control

@@ -64,12 +70,48 @@ struct ps8640 { struct drm_bridge *panel_bridge; struct mipi_dsi_device *dsi; struct i2c_client *page[MAX_DEVS];

•   struct regmap   *regmap[MAX_DEVS];
    struct regulator_bulk_data supplies[2];
    struct gpio_desc *gpio_reset;
    struct gpio_desc *gpio_powerdown;
    bool powered;
  

};

+static const struct regmap_config ps8640_regmap_config[] = {

•   [PAGE0_DP_CNTL] = {
  

•           COMMON_PS8640_REGMAP_CONFIG,
  

•           .max_register = 0xbf
  

•   },
  

•   [PAGE1_VDO_BDG] = {
  

•           COMMON_PS8640_REGMAP_CONFIG,
  

•           .max_register = 0xff
  

•   },
  

•   [PAGE2_TOP_CNTL] = {
  

•           COMMON_PS8640_REGMAP_CONFIG,
  

•           .max_register = 0xff
  

•   },
  

•   [PAGE3_DSI_CNTL1] = {
  

•           COMMON_PS8640_REGMAP_CONFIG,
  

•           .max_register = 0xff
  

•   },
  

•   [PAGE4_MIPI_PHY] = {
  

•           COMMON_PS8640_REGMAP_CONFIG,
  

•           .max_register = 0xff
  

•   },
  

•   [PAGE5_VPLL] = {
  

•           COMMON_PS8640_REGMAP_CONFIG,
  

•           .max_register = 0x7f
  

•   },
  

•   [PAGE6_DSI_CNTL2] = {
  

•           COMMON_PS8640_REGMAP_CONFIG,
  

•           .max_register = 0xff
  

•   },
  

•   [PAGE7_SPI_CNTL] = {
  

•           COMMON_PS8640_REGMAP_CONFIG,
  

•           .max_register = 0xff
  

•   }
  

nit: stylistically it's nice to add a "," after the last brace too. It's not technically needed but it makes diffs cleaner if another config is later added.

...

@@ -362,6 +390,10 @@ static int ps8640_probe(struct i2c_client *client)

    ps_bridge->page[PAGE0_DP_CNTL] = client;

•   ps_bridge->regmap[PAGE0_DP_CNTL] = devm_regmap_init_i2c(client, ps8640_regmap_config);
  

•   if (IS_ERR(ps_bridge->regmap[PAGE0_DP_CNTL]))
  

•           return PTR_ERR(ps_bridge->regmap[PAGE0_DP_CNTL]);
  

I'm a huge fan of dev_err_probe(). I wonder if it makes sense to use it here? Untested:

if (IS_ERR(ps_bridge->regmap[PAGE0_DP_CNTL])) return dev_err_probe(dev, PTR_ERR(ps_bridge->regmap[PAGE0_DP_CNTL]), "Error initting page 0 regmap\n");

All of that is just nits, so:

Reviewed-by: Douglas Anderson dianders@chromium.org