[RFC 8/9] HACK: drm/msm/mdp5: Add support for legacy cursor updates

[Archit Taneja]

On 12/19/2016 06:20 PM, Maarten Lankhorst wrote:
> Op 19-12-16 om 13:08 schreef Archit Taneja:
>> This code has been more or less picked up from the vc4 and intel
>> implementations of update_plane() funcs for cursor planes.
>>
>> The update_plane() func is usually the drm_atomic_helper_update_plane
>> func that will issue an atomic commit with the plane updates. Such
>> commits are not intended to be done faster than the vsync rate.
>>
>> The legacy cursor userspace API, on the other hand, expects the kernel
>> to handle cursor updates immediately.
>>
>> Create a fast path in update_plane, which updates the cursor registers
>> and flushes the configuration. The fast path is taken when there is only
>> a change in the cursor's position in the crtc, or a change in the
>> cursor's crop co-ordinates. For anything else, we go via the slow path.
>>
>> We take the slow path even whenever the fb changes, and even when there
>> is currently no fb tied to the plane. This should hopefully ensure that
>> we always take a slow path for every new fb. The slow path will ensure
>> that the fb is prepared/pinned etc.
>>
>> Cc:
>> Signed-off-by: Archit Taneja <architt at codeaurora.org>
>> ---
>> - Don't know what to do for locking here :/
> Shouldn't patch 9 be done first before 8?

Patch 9 introduces cursor drm_planes for the first time, so
anything done in 8 doesn't really take effect until we add
the planes in patch 9. So it's safe to have this order.

Archit


>
> ~Maarten
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