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Subject: Re: [PATCH 1/3] drm/amd: fix race in page flip job
To:     Yu Zhao <yuzhao@google.com>, David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>
Cc:     David Zhou <David1.Zhou@amd.com>,
        Daniel Stone <daniels@collabora.com>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        amd-gfx@lists.freedesktop.org, Samuel Li <Samuel.Li@amd.com>,
        Junwei Zhang <Jerry.Zhang@amd.com>,
        Harry Wentland <harry.wentland@amd.com>
References: <20181221031053.240161-1-yuzhao@google.com>
From:   =?UTF-8?Q?Michel_D=c3=a4nzer?= <michel@daenzer.net>
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Date:   Fri, 21 Dec 2018 09:56:52 +0100
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On 2018-12-21 4:10 a.m., Yu Zhao wrote:
> Fix race between page flip job submission and completion. We invoke
> page_flip callback to submit page flip job to GPU first and then set
> pflip_status. If GPU fires page flip done irq in between, its handler
> won't see the correct pflip_status thus will refuse to notify the job
> completion. The job will eventually times out.
> 
> Reverse the order of calling page_flip and setting pflip_status to
> fix the race.

There is no race, amdgpu_crtc->pflip_status is protected by dev->event_lock.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer