On Thu, Mar 20, 2014 at 3:31 AM, Daniel Vetter <daniel@xxxxxxxx> wrote:
> On Wed, Mar 19, 2014 at 10:26:13PM +0800, Daniel Kurtz wrote:
>> On Wed, Mar 19, 2014 at 7:51 PM, Daniel Vetter <daniel@xxxxxxxx> wrote:
>> > On Tue, Mar 18, 2014 at 05:22:49PM -0700, Matt Roper wrote:
>> >> Before we add additional types of planes to the DRM plane list, ensure
>> >> that existing loops over all planes continue to operate only on
>> >> "overlay" planes and ignore primary & cursor planes.
>> >>
>> >> Cc: Inki Dae <inki.dae@xxxxxxxxxxx>
>> >> Signed-off-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
>> >> ---
>> >> drivers/gpu/drm/exynos/exynos_drm_encoder.c | 6 ++++++
>> >> 1 file changed, 6 insertions(+)
>> >>
>> >> diff --git a/drivers/gpu/drm/exynos/exynos_drm_encoder.c b/drivers/gpu/drm/exynos/exynos_drm_encoder.c
>> >> index 06f1b2a..2fa2685 100644
>> >> --- a/drivers/gpu/drm/exynos/exynos_drm_encoder.c
>> >> +++ b/drivers/gpu/drm/exynos/exynos_drm_encoder.c
>> >> @@ -127,6 +127,9 @@ static void disable_plane_to_crtc(struct drm_device *dev,
>> >> * (encoder->crtc)
>> >> */
>> >> list_for_each_entry(plane, &dev->mode_config.plane_list, head) {
>> >> + if (plane->type != DRM_PLANE_TYPE_OVERLAY)
>> >
>> > I think a drm_for_each_legacy_plane iteration helper would be neat for
>> > this one and the following i915 patch.
>> > -Daniel
>> >
>> >> + continue;
>> >> +
>> >> if (plane->crtc == old_crtc) {
>> >> /*
>> >> * do not change below call order.
>> >> @@ -247,6 +250,9 @@ static void exynos_drm_encoder_disable(struct drm_encoder *encoder)
>> >>
>> >> /* all planes connected to this encoder should be also disabled. */
>> >> list_for_each_entry(plane, &dev->mode_config.plane_list, head) {
>> >> + if (plane->type != DRM_PLANE_TYPE_OVERLAY)
>> >> + continue;
>> >> +
>> >> if (plane->crtc == encoder->crtc)
>> >> plane->funcs->disable_plane(plane);
>> >> }
>>
>> The original loop disables all planes attached to a crtc when
>> disabling an encoder attached to the same crtc. It was added by:
>>
>> commit bcf4cef94294992f7cd11d5a90fa58b0eae6c795
>> Author: Inki Dae <inki.dae@xxxxxxxxxxx>
>> Date: Fri Aug 24 10:54:12 2012 -0700
>>
>> drm/exynos: Disable plane when released
>>
>> this patch ensures that each plane connected to encoder is disabled
>> when released, by adding disable callback function of encoder helper
>>
>> we had faced with one issue that invalid memory is accessed by dma
>> once drm is released and then the dma is turned on again. actually,
>> in our case, page fault was incurred with iommu. the reason is that
>> a gem buffer accessed by the dma is also released once drm is released.
>>
>> so this patch would fix this issue ensuring the dma is disabled
>> when released.
>>
>>
>> An encoder receives and encodes the mixed output of all of the
>> planes/overlays. It would seem that whether the individual planes
>> themselves are enabled or not should be completely independent of the
>> status any encoder. However, I find the code in exynos_drm_encoder.c
>> very difficult to follow, so perhaps there is some extra linkage
>> between encoder/crtc/plane that is exynos specific.
>>
>> In any case, judging from the commit message, this disable loop should
>> probably still iterate over all of the planes, not just the
>> "DRM_PLANE_TYPE_OVERLAY" ones. So, I think this new patch is
>> incorrect.
>
> It keeps full backwars compatibility with existing semantics, which is the
> right thing to do in such a case. It could be that exynos simply has a
> bug, but imo that should be a separate patch outside of this series.
Indeed... I missed the fact that in the existing code, the "priv"
(now primary) plane is not added to the plane_list, so it wouldn't
actually be disabled in this loop here anyway.
New question: are the planes that will become DRM_PLANE_TYPE_CURSOR
formerly "priv", or not?
If they were not, then I think the backwards- and forwards- compatible loop is:
list_for_each_entry(plane, &dev->mode_config.plane_list, head) {
if (plane->type == DRM_PLANE_TYPE_PRIMARY)
continue;
/* do something with legacy planes */
}
> -Daniel
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
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