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References: <20230223135635.30659-1-quic_sbillaka@quicinc.com> <20230223135635.30659-2-quic_sbillaka@quicinc.com>
In-Reply-To: <20230223135635.30659-2-quic_sbillaka@quicinc.com>
From:   Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date:   Thu, 23 Feb 2023 16:59:14 +0200
Message-ID: <CAA8EJprGzCBcWVkHHJxAtVOTuH5DeyYwKw-hHp+T1QvhvHXjsA@mail.gmail.com>
Subject: Re: [RFC PATCH 1/2] drm/msm/dp: enumerate edp panel during driver probe
To:     Sankeerth Billakanti <quic_sbillaka@quicinc.com>
Cc:     dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org,
        freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        robdclark@gmail.com, seanpaul@chromium.org, swboyd@chromium.org,
        quic_kalyant@quicinc.com, quic_abhinavk@quicinc.com,
        dianders@chromium.org, quic_khsieh@quicinc.com,
        quic_bjorande@quicinc.com, sean@poorly.run, airlied@linux.ie,
        daniel@ffwll.ch, quic_vproddut@quicinc.com
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Thu, 23 Feb 2023 at 15:57, Sankeerth Billakanti
<quic_sbillaka@quicinc.com> wrote:
>
> The eDP panel is identified and enumerated during probe of the panel-edp
> driver. The current DP driver triggers this panel-edp driver probe while
> getting the panel-bridge associated with the eDP panel from the platform
> driver bind. If the panel-edp probe is deferred, then the whole bunch of
> MDSS parent and child drivers have to defer and roll back.

No, MDSS has not been rolled back since 5.19. Please shift your
development on top of the current msm-next.

>
> So, we want to move the panel enumeration from bind to probe so that the
> probe defer is easier to handle and also both the drivers appear consistent
> in panel enumeration. This change moves the DP driver panel-bridge
> enumeration to probe.
>
> Signed-off-by: Sankeerth Billakanti <quic_sbillaka@quicinc.com>
> ---
>  drivers/gpu/drm/msm/dp/dp_aux.c     | 149 ++++++++++++++++++++++++++--
>  drivers/gpu/drm/msm/dp/dp_catalog.c |  12 +++
>  drivers/gpu/drm/msm/dp/dp_catalog.h |   1 +
>  drivers/gpu/drm/msm/dp/dp_display.c |  80 ++++++---------
>  4 files changed, 182 insertions(+), 60 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_aux.c b/drivers/gpu/drm/msm/dp/dp_aux.c
> index cc3efed593aa..5da95dfdeede 100644
> --- a/drivers/gpu/drm/msm/dp/dp_aux.c
> +++ b/drivers/gpu/drm/msm/dp/dp_aux.c
> @@ -110,7 +110,7 @@ static ssize_t dp_aux_write(struct dp_aux_private *aux,
>  }
>
>  static ssize_t dp_aux_cmd_fifo_tx(struct dp_aux_private *aux,
> -                             struct drm_dp_aux_msg *msg)
> +                             struct drm_dp_aux_msg *msg, bool poll)

What is the reason for working in polled mode rather than always using
the interrupts?

>  {
>         ssize_t ret;
>         unsigned long time_left;
> @@ -121,10 +121,16 @@ static ssize_t dp_aux_cmd_fifo_tx(struct dp_aux_private *aux,
>         if (ret < 0)
>                 return ret;
>
> -       time_left = wait_for_completion_timeout(&aux->comp,
> +       if (!poll) {
> +               time_left = wait_for_completion_timeout(&aux->comp,
>                                                 msecs_to_jiffies(250));
> -       if (!time_left)
> -               return -ETIMEDOUT;
> +               if (!time_left)
> +                       return -ETIMEDOUT;
> +       } else {
> +               ret = dp_catalog_aux_poll_and_get_hw_interrupt(aux->catalog);
> +               if (!ret)
> +                       dp_aux_isr(&aux->dp_aux);
> +       }
>
>         return ret;
>  }
> @@ -238,7 +244,7 @@ static void dp_aux_update_offset_and_segment(struct dp_aux_private *aux,
>   */
>  static void dp_aux_transfer_helper(struct dp_aux_private *aux,
>                                    struct drm_dp_aux_msg *input_msg,
> -                                  bool send_seg)
> +                                  bool send_seg, bool poll)
>  {
>         struct drm_dp_aux_msg helper_msg;
>         u32 message_size = 0x10;
> @@ -278,7 +284,7 @@ static void dp_aux_transfer_helper(struct dp_aux_private *aux,
>                 helper_msg.address = segment_address;
>                 helper_msg.buffer = &aux->segment;
>                 helper_msg.size = 1;
> -               dp_aux_cmd_fifo_tx(aux, &helper_msg);
> +               dp_aux_cmd_fifo_tx(aux, &helper_msg, poll);
>         }
>
>         /*
> @@ -292,7 +298,7 @@ static void dp_aux_transfer_helper(struct dp_aux_private *aux,
>         helper_msg.address = input_msg->address;
>         helper_msg.buffer = &aux->offset;
>         helper_msg.size = 1;
> -       dp_aux_cmd_fifo_tx(aux, &helper_msg);
> +       dp_aux_cmd_fifo_tx(aux, &helper_msg, poll);
>
>  end:
>         aux->offset += message_size;
> @@ -300,6 +306,122 @@ static void dp_aux_transfer_helper(struct dp_aux_private *aux,
>                 aux->segment = 0x0; /* reset segment at end of block */
>  }
>
> +/*
> + * This function does the real job to process an AUX transaction.
> + * It will call aux_reset() function to reset the AUX channel,
> + * if the waiting is timeout.
> + */
> +static ssize_t dp_aux_transfer_init(struct drm_dp_aux *dp_aux,
> +                              struct drm_dp_aux_msg *msg)
> +{
> +       ssize_t ret;
> +       int const aux_cmd_native_max = 16;
> +       int const aux_cmd_i2c_max = 128;
> +       struct dp_aux_private *aux;
> +
> +       aux = container_of(dp_aux, struct dp_aux_private, dp_aux);
> +
> +       aux->native = msg->request & (DP_AUX_NATIVE_WRITE & DP_AUX_NATIVE_READ);
> +
> +       /* Ignore address only message */
> +       if (msg->size == 0 || !msg->buffer) {
> +               msg->reply = aux->native ?
> +                       DP_AUX_NATIVE_REPLY_ACK : DP_AUX_I2C_REPLY_ACK;
> +               return msg->size;
> +       }
> +
> +       /* msg sanity check */
> +       if ((aux->native && msg->size > aux_cmd_native_max) ||
> +           msg->size > aux_cmd_i2c_max) {
> +               DRM_ERROR("%s: invalid msg: size(%zu), request(%x)\n",
> +                       __func__, msg->size, msg->request);
> +               return -EINVAL;
> +       }
> +
> +       mutex_lock(&aux->mutex);
> +       if (!aux->initted) {
> +               ret = -EIO;
> +               goto exit;
> +       }
> +
> +       /*
> +        * For eDP it's important to give a reasonably long wait here for HPD
> +        * to be asserted. This is because the panel driver may have _just_
> +        * turned on the panel and then tried to do an AUX transfer. The panel
> +        * driver has no way of knowing when the panel is ready, so it's up
> +        * to us to wait. For DP we never get into this situation so let's
> +        * avoid ever doing the extra long wait for DP.
> +        */
> +       if (aux->is_edp) {
> +               ret = dp_catalog_aux_wait_for_hpd_connect_state(aux->catalog);
> +               if (ret) {
> +                       DRM_DEBUG_DP("Panel not ready for aux transactions\n");
> +                       goto exit;
> +               }
> +       }
> +
> +       dp_aux_update_offset_and_segment(aux, msg);
> +       dp_aux_transfer_helper(aux, msg, true, true);
> +
> +       aux->read = msg->request & (DP_AUX_I2C_READ & DP_AUX_NATIVE_READ);
> +       aux->cmd_busy = true;
> +
> +       if (aux->read) {
> +               aux->no_send_addr = true;
> +               aux->no_send_stop = false;
> +       } else {
> +               aux->no_send_addr = true;
> +               aux->no_send_stop = true;
> +       }
> +
> +       ret = dp_aux_cmd_fifo_tx(aux, msg, true);
> +
> +       /* TODO: why is fifo_rx necessary here?
> +        * Ideally fifo_rx need not be executed for an aux write
> +        */
> +       ret = dp_aux_cmd_fifo_rx(aux, msg);
> +
> +       if (ret < 0) {
> +               if (aux->native) {
> +                       aux->retry_cnt++;
> +                       if (!(aux->retry_cnt % MAX_AUX_RETRIES))
> +                               dp_catalog_aux_update_cfg(aux->catalog);
> +               }
> +               /* reset aux if link is in connected state */
> +               if (dp_catalog_link_is_connected(aux->catalog))
> +                       dp_catalog_aux_reset(aux->catalog);
> +       } else {
> +               aux->retry_cnt = 0;
> +               switch (aux->aux_error_num) {
> +               case DP_AUX_ERR_NONE:
> +                       if (aux->read)
> +                               ret = dp_aux_cmd_fifo_rx(aux, msg);
> +                       msg->reply = aux->native ? DP_AUX_NATIVE_REPLY_ACK : DP_AUX_I2C_REPLY_ACK;
> +                       break;
> +               case DP_AUX_ERR_DEFER:
> +                       msg->reply = aux->native ?
> +                               DP_AUX_NATIVE_REPLY_DEFER : DP_AUX_I2C_REPLY_DEFER;
> +                       break;
> +               case DP_AUX_ERR_PHY:
> +               case DP_AUX_ERR_ADDR:
> +               case DP_AUX_ERR_NACK:
> +               case DP_AUX_ERR_NACK_DEFER:
> +                       msg->reply = aux->native ? DP_AUX_NATIVE_REPLY_NACK : DP_AUX_I2C_REPLY_NACK;
> +                       break;
> +               case DP_AUX_ERR_TOUT:
> +                       ret = -ETIMEDOUT;
> +                       break;
> +               }
> +       }
> +
> +       aux->cmd_busy = false;
> +
> +exit:
> +       mutex_unlock(&aux->mutex);
> +
> +       return ret;
> +}
> +
>  /*
>   * This function does the real job to process an AUX transaction.
>   * It will call aux_reset() function to reset the AUX channel,
> @@ -355,7 +477,7 @@ static ssize_t dp_aux_transfer(struct drm_dp_aux *dp_aux,
>         }
>
>         dp_aux_update_offset_and_segment(aux, msg);
> -       dp_aux_transfer_helper(aux, msg, true);
> +       dp_aux_transfer_helper(aux, msg, true, false);
>
>         aux->read = msg->request & (DP_AUX_I2C_READ & DP_AUX_NATIVE_READ);
>         aux->cmd_busy = true;
> @@ -368,7 +490,7 @@ static ssize_t dp_aux_transfer(struct drm_dp_aux *dp_aux,
>                 aux->no_send_stop = true;
>         }
>
> -       ret = dp_aux_cmd_fifo_tx(aux, msg);
> +       ret = dp_aux_cmd_fifo_tx(aux, msg, false);
>         if (ret < 0) {
>                 if (aux->native) {
>                         aux->retry_cnt++;
> @@ -535,6 +657,15 @@ struct drm_dp_aux *dp_aux_get(struct device *dev, struct dp_catalog *catalog,
>         aux->catalog = catalog;
>         aux->retry_cnt = 0;
>
> +       /*
> +        * Use the drm_dp_aux_init() to use the aux adapter
> +        * before registering aux with the DRM device.
> +        */
> +       aux->dp_aux.name = "dpu_dp_aux";
> +       aux->dp_aux.dev = dev;
> +       aux->dp_aux.transfer = dp_aux_transfer_init;
> +       drm_dp_aux_init(&aux->dp_aux);

How do you use the aux adapter? It should not be used before
aux->drm_dev is setup.

> +
>         return &aux->dp_aux;
>  }
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_catalog.c b/drivers/gpu/drm/msm/dp/dp_catalog.c
> index 676279d0ca8d..ccf0400176f0 100644
> --- a/drivers/gpu/drm/msm/dp/dp_catalog.c
> +++ b/drivers/gpu/drm/msm/dp/dp_catalog.c
> @@ -258,6 +258,18 @@ int dp_catalog_aux_wait_for_hpd_connect_state(struct dp_catalog *dp_catalog)
>                                 2000, 500000);
>  }
>
> +int dp_catalog_aux_poll_and_get_hw_interrupt(struct dp_catalog *dp_catalog)
> +{
> +       u32 aux;
> +       struct dp_catalog_private *catalog = container_of(dp_catalog,
> +                               struct dp_catalog_private, dp_catalog);
> +
> +       return readl_poll_timeout(catalog->io->dp_controller.ahb.base +
> +                               REG_DP_INTR_STATUS,
> +                               aux, aux & DP_INTERRUPT_STATUS1,
> +                               250, 250000);
> +}
> +
>  static void dump_regs(void __iomem *base, int len)
>  {
>         int i;
> diff --git a/drivers/gpu/drm/msm/dp/dp_catalog.h b/drivers/gpu/drm/msm/dp/dp_catalog.h
> index 1f717f45c115..ad4a9e0f71f2 100644
> --- a/drivers/gpu/drm/msm/dp/dp_catalog.h
> +++ b/drivers/gpu/drm/msm/dp/dp_catalog.h
> @@ -87,6 +87,7 @@ void dp_catalog_aux_enable(struct dp_catalog *dp_catalog, bool enable);
>  void dp_catalog_aux_update_cfg(struct dp_catalog *dp_catalog);
>  int dp_catalog_aux_wait_for_hpd_connect_state(struct dp_catalog *dp_catalog);
>  u32 dp_catalog_aux_get_irq(struct dp_catalog *dp_catalog);
> +int dp_catalog_aux_poll_and_get_hw_interrupt(struct dp_catalog *dp_catalog);
>
>  /* DP Controller APIs */
>  void dp_catalog_ctrl_state_ctrl(struct dp_catalog *dp_catalog, u32 state);
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index bde1a7ce442f..a5dcef040b74 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -275,13 +275,6 @@ static int dp_display_bind(struct device *dev, struct device *master,
>         dp->dp_display.drm_dev = drm;
>         priv->dp[dp->id] = &dp->dp_display;
>
> -       rc = dp->parser->parse(dp->parser);
> -       if (rc) {
> -               DRM_ERROR("device tree parsing failed\n");
> -               goto end;
> -       }
> -
> -
>         dp->drm_dev = drm;
>         dp->aux->drm_dev = drm;
>         rc = dp_aux_register(dp->aux);
> @@ -290,12 +283,6 @@ static int dp_display_bind(struct device *dev, struct device *master,
>                 goto end;
>         }
>
> -       rc = dp_power_client_init(dp->power);
> -       if (rc) {
> -               DRM_ERROR("Power client create failed\n");
> -               goto end;
> -       }
> -
>         rc = dp_register_audio_driver(dev, dp->audio);
>         if (rc) {
>                 DRM_ERROR("Audio registration Dp failed\n");
> @@ -787,6 +774,12 @@ static int dp_init_sub_modules(struct dp_display_private *dp)
>                 goto error;
>         }
>
> +       rc = dp->parser->parse(dp->parser);
> +       if (rc) {
> +               DRM_ERROR("device tree parsing failed\n");
> +               goto error;
> +       }
> +
>         dp->catalog = dp_catalog_get(dev, &dp->parser->io);
>         if (IS_ERR(dp->catalog)) {
>                 rc = PTR_ERR(dp->catalog);
> @@ -803,6 +796,12 @@ static int dp_init_sub_modules(struct dp_display_private *dp)
>                 goto error;
>         }
>
> +       rc = dp_power_client_init(dp->power);
> +       if (rc) {
> +               DRM_ERROR("Power client create failed\n");
> +               goto error;
> +       }
> +
>         dp->aux = dp_aux_get(dev, dp->catalog, dp->dp_display.is_edp);
>         if (IS_ERR(dp->aux)) {
>                 rc = PTR_ERR(dp->aux);
> @@ -1338,12 +1337,29 @@ static int dp_display_probe(struct platform_device *pdev)
>
>         platform_set_drvdata(pdev, &dp->dp_display);
>
> +       if (dp->dp_display.is_edp) {
> +               dp_display_host_init(dp);
> +               dp_display_host_phy_init(dp);
> +               dp_catalog_ctrl_hpd_config(dp->catalog);
> +
> +               rc = devm_of_dp_aux_populate_bus(dp->aux, NULL);

You should pass a real done_probing handler here, if you are going to
refactor this piece of code. The done_probing should then shut down
the resources and bind the component.

> +
> +               dp_display_host_phy_exit(dp);
> +               dp_display_host_deinit(dp);
> +
> +               if (rc) {
> +                       DRM_ERROR("failed to initialize panel, rc = %d\n", rc);
> +                       goto error;
> +               }
> +       }
> +
>         rc = component_add(&pdev->dev, &dp_display_comp_ops);
>         if (rc) {
>                 DRM_ERROR("component add failed, rc=%d\n", rc);
>                 dp_display_deinit_sub_modules(dp);
>         }
>
> +error:
>         return rc;
>  }
>
> @@ -1546,40 +1562,8 @@ static int dp_display_get_next_bridge(struct msm_dp *dp)
>  {
>         int rc;
>         struct dp_display_private *dp_priv;
> -       struct device_node *aux_bus;
> -       struct device *dev;
>
>         dp_priv = container_of(dp, struct dp_display_private, dp_display);
> -       dev = &dp_priv->pdev->dev;
> -       aux_bus = of_get_child_by_name(dev->of_node, "aux-bus");
> -
> -       if (aux_bus && dp->is_edp) {
> -               dp_display_host_init(dp_priv);
> -               dp_catalog_ctrl_hpd_config(dp_priv->catalog);
> -               dp_display_host_phy_init(dp_priv);
> -               enable_irq(dp_priv->irq);
> -
> -               /*
> -                * The code below assumes that the panel will finish probing
> -                * by the time devm_of_dp_aux_populate_ep_devices() returns.
> -                * This isn't a great assumption since it will fail if the
> -                * panel driver is probed asynchronously but is the best we
> -                * can do without a bigger driver reorganization.
> -                */
> -               rc = of_dp_aux_populate_bus(dp_priv->aux, NULL);
> -               of_node_put(aux_bus);
> -               if (rc)
> -                       goto error;
> -
> -               rc = devm_add_action_or_reset(dp->drm_dev->dev,
> -                                               of_dp_aux_depopulate_bus_void,
> -                                               dp_priv->aux);
> -               if (rc)
> -                       goto error;
> -       } else if (dp->is_edp) {
> -               DRM_ERROR("eDP aux_bus not found\n");
> -               return -ENODEV;
> -       }
>
>         /*
>          * External bridges are mandatory for eDP interfaces: one has to
> @@ -1597,12 +1581,6 @@ static int dp_display_get_next_bridge(struct msm_dp *dp)
>                 return 0;
>         }
>
> -error:
> -       if (dp->is_edp) {
> -               disable_irq(dp_priv->irq);
> -               dp_display_host_phy_exit(dp_priv);
> -               dp_display_host_deinit(dp_priv);
> -       }
>         return rc;
>  }
>
> --
> 2.39.0
>


-- 
With best wishes
Dmitry