Re: [PATCH 1/2] drm/rockchip: vop: Do check if an update is pending during disable

[Mark yao <mark.yao@xxxxxxxxxxxxxx>]

On 2016年05月24日 18:11, Tomeu Vizoso wrote:

Hi Tomeu
>
> Sorry for reply late.
> I don't agree the changes:
>
> - if (!state->enable)
> - return VOP_WIN_GET(vop_win->vop, vop_win->data, enable) == 0;
> + if (!state->enable &&
> +    VOP_WIN_GET(vop_win->vop, vop_win->data, enable) == 0)
> + return true;
>
> This changes actually would lead a bug.
> when we disable a plane, the vop_win_pending_is_complete would always return
> true, That is not allowed, would cause fb free too early.

Ok, maybe I need to ask you first what the original block of code
intended to achieve. The TRM I have is very terse and I don't find any
explanation there. The battery of tests I have pass just fine without
it.

> Does this patch is needed for "[PATCH 2/2] drm/rockchip: vop: Wait for
> pending events when disabling a CRTC"

Yes, this function is currently returning false when the pageflip has
been completed but the plan has been already disabled.

If you have any different idea of how to fix this bug, please share.

Thanks,

Tomeu

Hi Tomeu

@@ -504,6 +506,9 @@ static void vop_crtc_disable(struct drm_crtc *crtc)
 	if (!vop->is_enabled)
 		return;
 
+	if (crtc->state->event || vop->event)
+		vop_crtc_wait_for_update(crtc);
+

I think above change has some problem,

the function stack:
->drm swap state
->vop_crtc_disable
->vop_atomic_begin
->vop_atomic_flush

on vop_crtc_disable, crtc->state is new state, the crtc->state->event not yet update to vop, wait for  crtc->state->event here is wrong.

So I think the patch should be:
+	if (vop->event)
+		vop_crtc_wait_for_update(crtc);
+

Then the patch "drm/rockchip: vop: Do check if an update is pending during disable" should be no needed.

Thanks.

-- Ｍark Yao

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