Re: [PATCH] drm/rockchip: Return -EBUSY if there's already a pending flip event v2

From: Mark yao
Date: Fri Apr 01 2016 - 07:55:09 EST


On 2016å04æ01æ 19:47, Tomeu Vizoso wrote:
On 04/01/2016 01:26 PM, Mark yao wrote:
On 2016å03æ31æ 16:08, Tomeu Vizoso wrote:
As per the docs, atomic_commit should return -EBUSY "if an asycnhronous
updated is requested and there is an earlier updated pending".

v2: Use the status of the workqueue instead of vop->event, and don't add
a superfluous wait on the workqueue.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
---
drivers/gpu/drm/rockchip/rockchip_drm_fb.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_fb.c b/drivers/gpu/drm/rockchip/rockchip_drm_fb.c
index 3b8f652698f8..285f8cd5afe1 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_fb.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_fb.c
@@ -282,6 +282,9 @@ int rockchip_drm_atomic_commit(struct drm_device *dev,
struct rockchip_atomic_commit *commit = &private->commit;
int ret;
+ if (async && work_busy(&commit->work))
+ return -EBUSY;
+
Sorry for reply late.

There is a comment on work_busy function describe :

"the test result is unreliable and only useful as advisory hints or
for debugging."

I don't know if it's suitable to use it here, does some guys know it?
I'm not sure, but if the reason is the caveat explained in
find_worker_executing_work(), then it's probably safe (and would explain
how the function is used in other parts in the kernel).

And then, the "flush_work(&commit->work);" is no needed if return -EBUSY
here.
you can remove it at this patch.
We still need to wait if it's being called in sync mode.

Regards,

Tomeu
Hi Tomeuïï

on sync mode, flush is no needed, because that:
1, there is mutex_lock/mutex_unlock on this context, So only single process run into commit work;

2, sync mode will block on:
rockchip_atomic_commit_complete-->rockchip_atomic_wait_for_complete,

Thanks.


ret = drm_atomic_helper_prepare_planes(dev, state);
if (ret)
return ret;


--
ïark Yao






--
ïark Yao