Hi Emil,
On 2020-06-02 21:09, Emil Velikov wrote:
On Tue, 2 Jun 2020 at 15:49, Sai Prakash Ranjan saiprakash.ranjan@codeaurora.org wrote:
Hi Emil,
On 2020-06-02 19:43, Emil Velikov wrote:
Hi Krishna,
On Tue, 2 Jun 2020 at 08:17, Krishna Manikandan mkrishn@codeaurora.org wrote:
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 mkrishn@codeaurora.org
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.
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.
Thanks, Sai