On Sun, Aug 5, 2018 at 6:50 PM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote:
> Hi Vicente,
>
> On Sun, 5 Aug 2018 16:09:11 +0200
> Vicente Bergas <vicencb@xxxxxxxxx> wrote:
>
>> As explained by Robin Murphy:
>> > the IOMMU shutdown disables paging, so if the VOP is still
>> > scanning out then that will result in whatever IOVAs it was using now going
>> > straight out onto the bus as physical addresses.
>>
>> Suggested-by: JeffyChen <jeffy.chen@xxxxxxxxxxxxxx>
>> Suggested-by: Robin Murphy <robin.murphy@xxxxxxx>
>> Signed-off-by: Vicente Bergas <vicencb@xxxxxxxxx>
>> ---
>> drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 9 +++++++++
>> 1 file changed, 9 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
>> index f814d37b1db2..00a06768edb2 100644
>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
>> @@ -442,6 +442,14 @@ static int rockchip_drm_platform_remove(struct platform_device *pdev)
>> return 0;
>> }
>>
>> +static void rockchip_drm_platform_shutdown(struct platform_device *pdev)
>> +{
>> + struct drm_device *drm = platform_get_drvdata(pdev);
>> +
>> + if (drm)
>> + drm_atomic_helper_shutdown(drm);
>
> I'm not completely sure this is the right thing to do here. We want
> shutdown to teardown the whole thing, not just the DRM context.
>
> The driver already calls drm_atomic_helper_shutdown as part of the
> unbind sequence, which looks very much like what we're trying to
> achieve here.
OK, but maybe it is calling drm_atomic_helper_shutdown too late
because this patch makes a difference and does indeed fix the issue.
Anyways, please, apply your version if you have reasons to think it
is better suited to do the task.
>
> I've already posted a patch[1] which calls the .remove handler,
> ensuring that the whole infrastructure gets torn down at shutdown time.
That is funny: after months of having reported the issue, we both
sent a patch to fix it in less than 3 hours difference!
Regards,
Vicente.
>
> Thanks,
>
> M.
>
> [1] https://www.spinics.net/lists/arm-kernel/msg670229.html
> --
> Without deviation from the norm, progress is not possible.
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