drm/msm: add shutdown support for display platform_driver

Define shutdown callback for display drm driver, so as to disable all the CRTCS when shutdown notification is received by the driver.

This change will turn off the timing engine so that no display transactions are requested while mmu translations are getting disabled during reboot sequence.

Signed-off-by Krishna Manikandan <[email protected]>

Hi Krishna,

Quoted 10 lines · Krishna Manikandan

Define shutdown callback for display drm driver, so as to disable all the CRTCS when shutdown notification is received by the driver.

This change will turn off the timing engine so that no display transactions are requested while mmu translations are getting disabled during reboot sequence.

Quoted 2 lines

Signed-off-by Krishna Manikandan <[email protected]>

AFAICT atomics is setup in msm_drm_ops::bind and shutdown in msm_drm_ops::unbind.

Are you saying that unbind never triggers? If so, then we should really fix that instead, since this patch seems more like a workaround.

Hi Emil,

Quoted 14 lines · Emil Velikov

Hi Krishna,

Quoted 10 lines · Krishna Manikandan

Define shutdown callback for display drm driver, so as to disable all the CRTCS when shutdown notification is received by the driver.

This change will turn off the timing engine so that no display transactions are requested while mmu translations are getting disabled during reboot sequence.

Quoted 9 lines

Quoted 2 lines

Signed-off-by Krishna Manikandan <[email protected]>

AFAICT atomics is setup in msm_drm_ops::bind and shutdown in msm_drm_ops::unbind.

Are you saying that unbind never triggers? If so, then we should really fix that instead, since this patch seems more like a workaround.

Which path do you suppose that the unbind should be called from, remove callback? Here we are talking about the drivers which are builtin, where remove callbacks are not called from the driver core during reboot/shutdown,
instead shutdown callbacks are called which needs to be defined in order to
trigger unbind. So AFAICS there is nothing to be fixed.

Quoted 28 lines · Sai Prakash Ranjan

Hi Emil,

Quoted 14 lines · Emil Velikov

Hi Krishna,

Quoted 10 lines · Krishna Manikandan

Define shutdown callback for display drm driver, so as to disable all the CRTCS when shutdown notification is received by the driver.

This change will turn off the timing engine so that no display transactions are requested while mmu translations are getting disabled during reboot sequence.

Quoted 9 lines

Quoted 2 lines

Signed-off-by Krishna Manikandan <[email protected]>

AFAICT atomics is setup in msm_drm_ops::bind and shutdown in msm_drm_ops::unbind.

Are you saying that unbind never triggers? If so, then we should really fix that instead, since this patch seems more like a workaround.

Quoted 8 lines

Which path do you suppose that the unbind should be called from, remove callback? Here we are talking about the drivers which are builtin, where remove callbacks are not called from the driver core during reboot/shutdown,
instead shutdown callbacks are called which needs to be defined in order to
trigger unbind. So AFAICS there is nothing to be fixed.

Interesting - in drm effectively only drm panels implement .shutdown. So my naive assumption was that .remove was used implicitly by core, as part of the shutdown process. Yet that's not the case, so it seems that many drivers could use some fixes.

Then again, that's an existing problem which is irrelevant for msm. -Emil

Hi Emil,

Quoted 41 lines · Emil Velikov

Quoted 28 lines · Sai Prakash Ranjan

Hi Emil,

Quoted 14 lines · Emil Velikov

Hi Krishna,

Quoted 10 lines · Krishna Manikandan

Define shutdown callback for display drm driver, so as to disable all the CRTCS when shutdown notification is received by the driver.

This change will turn off the timing engine so that no display transactions are requested while mmu translations are getting disabled during reboot sequence.

Quoted 9 lines

Quoted 2 lines

Signed-off-by Krishna Manikandan <[email protected]>

AFAICT atomics is setup in msm_drm_ops::bind and shutdown in msm_drm_ops::unbind.

Are you saying that unbind never triggers? If so, then we should really fix that instead, since this patch seems more like a workaround.

Quoted 11 lines

Which path do you suppose that the unbind should be called from, remove
callback? Here we are talking about the drivers which are builtin, where
remove callbacks are not called from the driver core during reboot/shutdown,
instead shutdown callbacks are called which needs to be defined in order
to
trigger unbind. So AFAICS there is nothing to be fixed.

Quoted 7 lines

Interesting - in drm effectively only drm panels implement .shutdown. So my naive assumption was that .remove was used implicitly by core, as part of the shutdown process. Yet that's not the case, so it seems that many drivers could use some fixes.

Then again, that's an existing problem which is irrelevant for msm. -Emil

To give more context, we are actually targeting the clients/consumers of SMMU/IOMMU here because we have to make sure that before the supplier (SMMU) shuts down, its consumers/clients need to be shutdown properly. Now the ordering of this is taken care in the SMMU driver via device_link
which makes sure that consumer shutdown callbacks are called first, but we
need to define shutdown callbacks for all its consumers to make sure we actually shutdown the clients or else it would invite the crashes during reboot
which in this case was seen for display.

Define shutdown callback for display drm driver, so as to disable all the CRTCS when shutdown notification is received by the driver.

This change will turn off the timing engine so that no display transactions are requested while mmu translations are getting disabled during reboot sequence.

Signed-off-by Krishna Manikandan <[email protected]>

Changes in v2:
- Remove NULL check from msm_pdev_shutdown (Stephen Boyd)
- Change commit text to reflect when this issue was uncovered (Sai Prakash Ranjan)

---
 drivers/gpu/drm/msm/msm_drv.c | 8 ++++++++
 1 file changed, 8 insertions(+)

drivers/gpu/drm/msm/msm_drv.c +7 -0

index e4b750b..94e3963 100644
@@ -1322,6 +1322,13 @@ static int msm_pdev_remove(struct 
 platform_device *pdev)
 	return 0;
 }
 
+static void msm_pdev_shutdown(struct platform_device *pdev)
+{
+	struct drm_device *drm = platform_get_drvdata(pdev);
+
+	drm_atomic_helper_shutdown(drm);
+}
+
 static const struct of_device_id dt_match[] = {
 	{ .compatible = "qcom,mdp4", .data = (void *)KMS_MDP4 },

drivers/gpu/drm/msm/msm_drv.c +1 -0

 	{ .compatible = "qcom,mdss", .data = (void *)KMS_MDP5 },

@@ -1334,6 +1341,7 @@ static int msm_pdev_remove(struct platform_device 
 *pdev)
 static struct platform_driver msm_platform_driver = {
 	.probe      = msm_pdev_probe,
 	.remove     = msm_pdev_remove,
+	.shutdown   = msm_pdev_shutdown,
 	.driver     = {
 		.name   = "msm",

.of_match_table = dt_match,

Hi,

Quoted 42 lines · Krishna Manikandan

Define shutdown callback for display drm driver, so as to disable all the CRTCS when shutdown notification is received by the driver.

This change will turn off the timing engine so that no display transactions are requested while mmu translations are getting disabled during reboot sequence.

Signed-off-by Krishna Manikandan <[email protected]>

Changes in v2:
- Remove NULL check from msm_pdev_shutdown (Stephen Boyd)
- Change commit text to reflect when this issue was uncovered (Sai Prakash Ranjan)

---
 drivers/gpu/drm/msm/msm_drv.c | 8 ++++++++
 1 file changed, 8 insertions(+)

drivers/gpu/drm/msm/msm_drv.c +7 -0

index e4b750b..94e3963 100644
@@ -1322,6 +1322,13 @@ static int msm_pdev_remove(struct
 platform_device *pdev)
      return 0;
 }
 
+static void msm_pdev_shutdown(struct platform_device *pdev)
+{
+     struct drm_device *drm = platform_get_drvdata(pdev);
+
+     drm_atomic_helper_shutdown(drm);
+}
+
 static const struct of_device_id dt_match[] = {
      { .compatible = "qcom,mdp4", .data = (void *)KMS_MDP4 },

      { .compatible = "qcom,mdss", .data = (void *)KMS_MDP5 },

drivers/gpu/drm/msm/msm_drv.c +0 -0

@@ -1334,6 +1341,7 @@ static int msm_pdev_remove(struct platform_device
 *pdev)
 static struct platform_driver msm_platform_driver = {

Quoted 6 lines

drivers/gpu/drm/msm/msm_drv.c +1 -0

      .probe      = msm_pdev_probe,
      .remove     = msm_pdev_remove,
+     .shutdown   = msm_pdev_shutdown,
      .driver     = {
              .name   = "msm",

.of_match_table = dt_match,

Any more comments on this patch?

Thanks,
Sai

--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation

Quoted 46 lines · Sai Prakash Ranjan

Hi,

Quoted 42 lines · Krishna Manikandan

Define shutdown callback for display drm driver, so as to disable all the CRTCS when shutdown notification is received by the driver.

This change will turn off the timing engine so that no display transactions are requested while mmu translations are getting disabled during reboot sequence.

Signed-off-by Krishna Manikandan <[email protected]>

Changes in v2:
- Remove NULL check from msm_pdev_shutdown (Stephen Boyd)
- Change commit text to reflect when this issue was uncovered (Sai Prakash Ranjan)

---
 drivers/gpu/drm/msm/msm_drv.c | 8 ++++++++
 1 file changed, 8 insertions(+)

drivers/gpu/drm/msm/msm_drv.c +7 -0

index e4b750b..94e3963 100644
@@ -1322,6 +1322,13 @@ static int msm_pdev_remove(struct
 platform_device *pdev)
      return 0;
 }
 
+static void msm_pdev_shutdown(struct platform_device *pdev)
+{
+     struct drm_device *drm = platform_get_drvdata(pdev);
+
+     drm_atomic_helper_shutdown(drm);
+}
+
 static const struct of_device_id dt_match[] = {
      { .compatible = "qcom,mdp4", .data = (void *)KMS_MDP4 },

      { .compatible = "qcom,mdss", .data = (void *)KMS_MDP5 },

drivers/gpu/drm/msm/msm_drv.c +0 -0

@@ -1334,6 +1341,7 @@ static int msm_pdev_remove(struct platform_device
 *pdev)
 static struct platform_driver msm_platform_driver = {

Quoted 8 lines

Quoted 6 lines

drivers/gpu/drm/msm/msm_drv.c +1 -0

      .probe      = msm_pdev_probe,
      .remove     = msm_pdev_remove,
+     .shutdown   = msm_pdev_shutdown,
      .driver     = {
              .name   = "msm",

.of_match_table = dt_match,

Any more comments on this patch?

sorry, I managed to overlook this earlier.. I've pulled it in to msm-next