RE: [RFC PATCH 1/2] drm/msm/dp: enumerate edp panel during driver probe

[Sankeerth Billakanti (QUIC)]

Hi Dmitry,

>>>>
>>>> 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.
>>>
>>
>> Okay, I will move to the msm-next tip.
>>
>>>>
>>>> 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@xxxxxxxxxxx>
>>>> ---
>>>>   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?
>>>
>>
>> The mdss interrupts will be enabled and can be used after msm_irq_install
>from msm_drm_bind.
>> We want to perform aux transactions during probe. The aux data
>> transmission is followed by an interrupt to indicate successful transmission
>status and reply information.
>
>This is the price of developing on, let me guess, 5.15. Nowadays MDSS
>interrupts are enabled and can be used during dp_display_probe() and
>dp_display_bind(). If they can not for some reason, this is an issue that must
>be fixed. Please reconsider your approach after rebasing onto msm-next or
>6.3-rc1.
>

On the msm-next also, I see the mdss irq is enabled from bind (in msm_drv.c). 
msm_drm_bind -> msm_drm_init -> msm_irq_install

Currently, interrupts will not be available during the dp_display_probe.
Is there a patch series which is enabling IRQs during mdss probe?

>>
>> As interrupts are not enabled, I took this polling approach for aux interrupts
>during probe.
>>
>>>>   {
>>>>          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.
>>>
>>
>> The drm_dev registration happens during the bind. But we need to use aux
>during probe.
>>
>> The kernel doc for the drm_dp_aux_init function suggested we can use
>> the adapter before drm_dev registration. So, I used this function to enable
>the aux usage during probe.
>
>Then please also change __drm_printk() to use (drm) ? (drm->dev) : NULL as
>a first argument to dev_##level##type. Otherwise the first AUX transfer error
>before aux->drm_dev is set will oops the kernel. See how
>drm_err() is expanded.
>

Okay, will add this also.

>>
>> /**
>>   * drm_dp_aux_init() - minimally initialise an aux channel
>>   * @aux: DisplayPort AUX channel
>>   *
>>   * If you need to use the drm_dp_aux's i2c adapter prior to registering it
>with
>>   * the outside world, call drm_dp_aux_init() first.
>>
>>>> +
>>>>          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.
>>>
>>
>> I removed the resource enabling part from probe in the next patch where I
>implemented pm_runtime_ops.
>> I moved the host_init, phy_init and hpd_config into runtime_resume and
>calling pm_runtime_get_sync from aux_transfer.
>
>Next patch doesn't exist at this point. So, please, either reorder them,
>or make this patch correct per se.
>
>Also, the key part is a call to component_add(). It should come from
>done_probing callback. AUX bus probing is asynchronous. The kernel
>registers a device and then it might take some time for the correct
>driver to be loaded, etc. We clearly expect dp_display_bind to be used
>only when the panel has been probed.
>


Okay, will add the done_probe function

>>
>>>> +
>>>> +               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
>
>--
>With best wishes
>Dmitry