Re: [v2] drm/msm: add shutdown support for display platform_driver

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Hi Emil,

On 2020-06-02 19:43, Emil Velikov wrote:
Hi Krishna,

On Tue, 2 Jun 2020 at 08:17, Krishna Manikandan <mkrishn@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx>

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.

msm_pdev_shutdown()
 platform_drv_shutdown()
  device_shutdown()
   kernel_restart_prepare()
    kernel_restart()
     __arm64_sys_reboot()

Thanks,
Sai

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