Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753799AbcDALrh (ORCPT ); Fri, 1 Apr 2016 07:47:37 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:49990 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751902AbcDALrg (ORCPT ); Fri, 1 Apr 2016 07:47:36 -0400 Subject: Re: [PATCH] drm/rockchip: Return -EBUSY if there's already a pending flip event v2 To: Mark yao , linux-kernel@vger.kernel.org References: <1459411680-6176-1-git-send-email-tomeu.vizoso@collabora.com> <56FE5AE9.40806@rock-chips.com> Cc: David Airlie , Heiko Stuebner , dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org From: Tomeu Vizoso Message-ID: <56FE5FD2.2050106@collabora.com> Date: Fri, 1 Apr 2016 13:47:30 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <56FE5AE9.40806@rock-chips.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1754 Lines: 57 On 04/01/2016 01:26 PM, Mark yao wrote: > On 2016年03月31日 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 >> --- >> 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 >> ret = drm_atomic_helper_prepare_planes(dev, state); >> if (ret) >> return ret; > > > > -- > Ｍark Yao >