[v4,3/4] drm/bridge: anx7625: Support reading edid through aux channel

Support reading edid through aux channel if panel is connected to aux
bus. Extend anx7625_aux_dpcd_trans() to implement aux transfer function:

1. panel is populated in devm_of_dp_aux_populate_ep_devices(), so move
   anx7625_parse_dt() after.
2. Use pm runtime autosuspend since aux transfer function is called
   multiple times when reading edid.
3. No-op if aux transfer length is 0.

Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Reviewed-by: Xin Ji <xji@analogixsemi.com>
---
v3->v4:
rebase to latest drm-misc-next
---
 drivers/gpu/drm/bridge/analogix/anx7625.c | 120 ++++++++++++++++++----
 drivers/gpu/drm/bridge/analogix/anx7625.h |   1 +
 2 files changed, 103 insertions(+), 18 deletions(-)

On Tue, 18 Jan 2022 at 10:20, Hsin-Yi Wang <hsinyi@chromium.org> wrote:
>
> Support reading edid through aux channel if panel is connected to aux
> bus. Extend anx7625_aux_dpcd_trans() to implement aux transfer function:
>
> 1. panel is populated in devm_of_dp_aux_populate_ep_devices(), so move
>    anx7625_parse_dt() after.
> 2. Use pm runtime autosuspend since aux transfer function is called
>    multiple times when reading edid.
> 3. No-op if aux transfer length is 0.
>
> Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
> Reviewed-by: Xin Ji <xji@analogixsemi.com>
> ---
> v3->v4:
> rebase to latest drm-misc-next
> ---
>  drivers/gpu/drm/bridge/analogix/anx7625.c | 120 ++++++++++++++++++----
>  drivers/gpu/drm/bridge/analogix/anx7625.h |   1 +
>  2 files changed, 103 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> index b7e3373994b480..50b9c98277f0d7 100644
> --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
> @@ -24,6 +24,7 @@
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_bridge.h>
>  #include <drm/drm_crtc_helper.h>
> +#include <drm/drm_dp_aux_bus.h>

drivers/gpu/drm/bridge/analogix/anx7625.c:27:10: fatal error:
drm/drm_dp_aux_bus.h: No such file or directory
   27 | #include <drm/drm_dp_aux_bus.h>

drm/dp/rm_dp_aux_bus.h is probably the correct path.

>  #include <drm/dp/drm_dp_helper.h>
>  #include <drm/drm_edid.h>
>  #include <drm/drm_hdcp.h>
> @@ -231,19 +232,23 @@ static int wait_aux_op_finish(struct anx7625_data *ctx)
>         return 0;
>  }
>
> -static int anx7625_aux_dpcd_trans(struct anx7625_data *ctx, u8 op,
> -                                 u32 address, u8 len, u8 *buf)
> +static int anx7625_aux_trans(struct anx7625_data *ctx, u8 op, u32 address,
> +                            u8 len, u8 *buf)
>  {
>         struct device *dev = &ctx->client->dev;
>         int ret;
>         u8 addrh, addrm, addrl;
>         u8 cmd;
> +       bool is_write = !(op & DP_AUX_I2C_READ);
>
> -       if (len > MAX_DPCD_BUFFER_SIZE) {
> +       if (len > DP_AUX_MAX_PAYLOAD_BYTES) {
>                 dev_err(dev, "exceed aux buffer len.\n");
>                 return -EINVAL;
>         }
>
> +       if (!len)
> +               return len;
> +
>         addrl = address & 0xFF;
>         addrm = (address >> 8) & 0xFF;
>         addrh = (address >> 16) & 0xFF;
> @@ -262,7 +267,7 @@ static int anx7625_aux_dpcd_trans(struct anx7625_data *ctx, u8 op,
>         ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
>                                  AP_AUX_ADDR_19_16, addrh);
>
> -       if (op == DP_AUX_NATIVE_WRITE)
> +       if (is_write)
>                 ret |= anx7625_reg_block_write(ctx, ctx->i2c.rx_p0_client,
>                                                AP_AUX_BUFF_START, len, buf);
>         /* Enable aux access */
> @@ -275,14 +280,14 @@ static int anx7625_aux_dpcd_trans(struct anx7625_data *ctx, u8 op,
>         }
>
>         ret = wait_aux_op_finish(ctx);
> -       if (ret) {
> +       if (ret < 0) {
>                 dev_err(dev, "aux IO error: wait aux op finish.\n");
>                 return ret;
>         }
>
>         /* Write done */
> -       if (op == DP_AUX_NATIVE_WRITE)
> -               return 0;
> +       if (is_write)
> +               return len;
>
>         /* Read done, read out dpcd data */
>         ret = anx7625_reg_block_read(ctx, ctx->i2c.rx_p0_client,
> @@ -292,7 +297,7 @@ static int anx7625_aux_dpcd_trans(struct anx7625_data *ctx, u8 op,
>                 return -EIO;
>         }
>
> -       return 0;
> +       return len;
>  }
>
>  static int anx7625_video_mute_control(struct anx7625_data *ctx,
> @@ -867,7 +872,7 @@ static int anx7625_hdcp_enable(struct anx7625_data *ctx)
>         }
>
>         /* Read downstream capability */
> -       anx7625_aux_dpcd_trans(ctx, DP_AUX_NATIVE_READ, 0x68028, 1, &bcap);
> +       anx7625_aux_trans(ctx, DP_AUX_NATIVE_READ, 0x68028, 1, &bcap);
>         if (!(bcap & 0x01)) {
>                 pr_warn("downstream not support HDCP 1.4, cap(%x).\n", bcap);
>                 return 0;
> @@ -956,7 +961,7 @@ static void anx7625_dp_stop(struct anx7625_data *ctx)
>         dev_dbg(dev, "notify downstream enter into standby\n");
>         /* Downstream monitor enter into standby mode */
>         data = 2;
> -       ret |= anx7625_aux_dpcd_trans(ctx, DP_AUX_NATIVE_WRITE, 0x000600, 1, &data);
> +       ret |= anx7625_aux_trans(ctx, DP_AUX_NATIVE_WRITE, 0x000600, 1, &data);
>         if (ret < 0)
>                 DRM_DEV_ERROR(dev, "IO error : mute video fail\n");
>
> @@ -1655,11 +1660,56 @@ static int anx7625_parse_dt(struct device *dev,
>         return 0;
>  }
>
> +static bool anx7625_of_panel_on_aux_bus(struct device *dev)
> +{
> +       struct device_node *bus, *panel;
> +
> +       bus = of_get_child_by_name(dev->of_node, "aux-bus");
> +       if (!bus)
> +               return false;
> +
> +       panel = of_get_child_by_name(bus, "panel");
> +       of_node_put(bus);
> +       if (!panel)
> +               return false;
> +       of_node_put(panel);
> +
> +       return true;
> +}
> +
>  static inline struct anx7625_data *bridge_to_anx7625(struct drm_bridge *bridge)
>  {
>         return container_of(bridge, struct anx7625_data, bridge);
>  }
>
> +static ssize_t anx7625_aux_transfer(struct drm_dp_aux *aux,
> +                                    struct drm_dp_aux_msg *msg)

checkpatch --strict is unhappy about the above line not using as many
tabs as possible.

> +{
> +       struct anx7625_data *ctx = container_of(aux, struct anx7625_data, aux);
> +       struct device *dev = &ctx->client->dev;
> +       u8 request = msg->request & ~DP_AUX_I2C_MOT;
> +       int ret = 0;
> +
> +       pm_runtime_get_sync(dev);
> +       msg->reply = 0;
> +       switch (request) {
> +       case DP_AUX_NATIVE_WRITE:
> +       case DP_AUX_I2C_WRITE:
> +       case DP_AUX_NATIVE_READ:
> +       case DP_AUX_I2C_READ:
> +               break;
> +       default:
> +               ret = -EINVAL;
> +       }
> +       if (!ret)
> +               ret = anx7625_aux_trans(ctx, msg->request, msg->address,
> +                                       msg->size, msg->buffer);
> +       pm_runtime_mark_last_busy(dev);
> +       pm_runtime_put_autosuspend(dev);
> +
> +       return ret;
> +}
> +
>  static struct edid *anx7625_get_edid(struct anx7625_data *ctx)
>  {
>         struct device *dev = &ctx->client->dev;
> @@ -2066,6 +2116,13 @@ static int anx7625_bridge_attach(struct drm_bridge *bridge,
>                 return -ENODEV;
>         }
>
> +       ctx->aux.drm_dev = bridge->dev;
> +       err = drm_dp_aux_register(&ctx->aux);
> +       if (err) {
> +               dev_err(dev, "failed to register aux channel: %d\n", err);
> +               return err;
> +       }
> +
>         if (ctx->pdata.panel_bridge) {
>                 err = drm_bridge_attach(bridge->encoder,
>                                         ctx->pdata.panel_bridge,
> @@ -2079,6 +2136,13 @@ static int anx7625_bridge_attach(struct drm_bridge *bridge,
>         return 0;
>  }
>
> +static void anx7625_bridge_detach(struct drm_bridge *bridge)
> +{
> +       struct anx7625_data *ctx = bridge_to_anx7625(bridge);
> +
> +       drm_dp_aux_unregister(&ctx->aux);
> +}
> +
>  static enum drm_mode_status
>  anx7625_bridge_mode_valid(struct drm_bridge *bridge,
>                           const struct drm_display_info *info,
> @@ -2344,6 +2408,7 @@ static struct edid *anx7625_bridge_get_edid(struct drm_bridge *bridge,
>
>  static const struct drm_bridge_funcs anx7625_bridge_funcs = {
>         .attach = anx7625_bridge_attach,
> +       .detach = anx7625_bridge_detach,
>         .mode_valid = anx7625_bridge_mode_valid,
>         .mode_set = anx7625_bridge_mode_set,
>         .atomic_check = anx7625_bridge_atomic_check,
> @@ -2501,6 +2566,12 @@ static const struct dev_pm_ops anx7625_pm_ops = {
>                            anx7625_runtime_pm_resume, NULL)
>  };
>
> +static void anx7625_runtime_disable(void *data)
> +{
> +       pm_runtime_dont_use_autosuspend(data);
> +       pm_runtime_disable(data);
> +}
> +
>  static int anx7625_i2c_probe(struct i2c_client *client,
>                              const struct i2c_device_id *id)
>  {
> @@ -2523,13 +2594,6 @@ static int anx7625_i2c_probe(struct i2c_client *client,
>
>         pdata = &platform->pdata;
>
> -       ret = anx7625_parse_dt(dev, pdata);
> -       if (ret) {
> -               if (ret != -EPROBE_DEFER)
> -                       DRM_DEV_ERROR(dev, "fail to parse DT : %d\n", ret);
> -               return ret;
> -       }
> -
>         platform->client = client;
>         i2c_set_clientdata(client, platform);
>
> @@ -2577,6 +2641,19 @@ static int anx7625_i2c_probe(struct i2c_client *client,
>                 }
>         }
>
> +       platform->aux.name = "anx7625-aux";
> +       platform->aux.dev = dev;
> +       platform->aux.transfer = anx7625_aux_transfer;
> +       drm_dp_aux_init(&platform->aux);
> +       devm_of_dp_aux_populate_ep_devices(&platform->aux);
> +
> +       ret = anx7625_parse_dt(dev, pdata);
> +       if (ret) {
> +               if (ret != -EPROBE_DEFER)
> +                       DRM_DEV_ERROR(dev, "fail to parse DT : %d\n", ret);
> +               return ret;
> +       }
> +
>         if (anx7625_register_i2c_dummy_clients(platform, client) != 0) {
>                 ret = -ENOMEM;
>                 DRM_DEV_ERROR(dev, "fail to reserve I2C bus.\n");
> @@ -2584,6 +2661,12 @@ static int anx7625_i2c_probe(struct i2c_client *client,
>         }
>
>         pm_runtime_enable(dev);
> +       pm_runtime_set_autosuspend_delay(dev, 1000);
> +       pm_runtime_use_autosuspend(dev);
> +       pm_suspend_ignore_children(dev, true);
> +       ret = devm_add_action_or_reset(dev, anx7625_runtime_disable, dev);
> +       if (ret)
> +               return ret;
>
>         if (!platform->pdata.low_power_mode) {
>                 anx7625_disable_pd_protocol(platform);
> @@ -2596,7 +2679,8 @@ static int anx7625_i2c_probe(struct i2c_client *client,
>
>         platform->bridge.funcs = &anx7625_bridge_funcs;
>         platform->bridge.of_node = client->dev.of_node;
> -       platform->bridge.ops = DRM_BRIDGE_OP_EDID;
> +       if (!anx7625_of_panel_on_aux_bus(&client->dev))
> +               platform->bridge.ops |= DRM_BRIDGE_OP_EDID;
>         if (!platform->pdata.panel_bridge)
>                 platform->bridge.ops |= DRM_BRIDGE_OP_HPD |
>                                         DRM_BRIDGE_OP_DETECT;
> diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.h b/drivers/gpu/drm/bridge/analogix/anx7625.h
> index 64a8ab56529404..edbbfe410a56e8 100644
> --- a/drivers/gpu/drm/bridge/analogix/anx7625.h
> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.h
> @@ -472,6 +472,7 @@ struct anx7625_data {
>         u8 bridge_attached;
>         struct drm_connector *connector;
>         struct mipi_dsi_device *dsi;
> +       struct drm_dp_aux aux;
>  };
>
>  #endif  /* __ANX7625_H__ */
> --
> 2.34.1.703.g22d0c6ccf7-goog
>