linux-kernel - Re: [PATCH] drm/mediatek: dsi: Move mtk_dsi_stop() call back to mtk_dsi

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Date:   Mon, 19 Sep 2022 15:32:52 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Hsin-Yi Wang <hsinyi@...omium.org>,
        Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>
Cc:     Chun-Kuang Hu <chunkuang.hu@...nel.org>, kernel@...labora.com,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Jitao Shi <jitao.shi@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Rex-BC Chen <rex-bc.chen@...iatek.com>,
        Xinlei Lee <xinlei.lee@...iatek.com>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH] drm/mediatek: dsi: Move mtk_dsi_stop() call back to
 mtk_dsi_poweroff()

Il 19/09/22 10:40, Hsin-Yi Wang ha scritto:
> On Mon, Sep 19, 2022 at 4:39 PM Nícolas F. R. A. Prado
> <nfraprado@...labora.com> wrote:
>>
>> As the comment right before the mtk_dsi_stop() call advises,
>> mtk_dsi_stop() should only be called after
>> mtk_drm_crtc_atomic_disable(). That's because that function calls
>> drm_crtc_wait_one_vblank(), which requires the vblank irq to be enabled.
>>
>> Previously mtk_dsi_stop(), being in mtk_dsi_poweroff() and guarded by a
>> refcount, would only be called at the end of
>> mtk_drm_crtc_atomic_disable(), through the call to mtk_crtc_ddp_hw_fini().
>> Commit cde7e2e35c28 ("drm/mediatek: Separate poweron/poweroff from
>> enable/disable and define new funcs") moved the mtk_dsi_stop() call to
>> mtk_output_dsi_disable(), causing it to be called before
>> mtk_drm_crtc_atomic_disable(), and consequently generating vblank
>> timeout warnings during suspend.
>>
>> Move the mtk_dsi_stop() call back to mtk_dsi_poweroff() so that we have
>> a working vblank irq during mtk_drm_crtc_atomic_disable() and stop
>> getting vblank timeout warnings.
>>
>> Fixes: cde7e2e35c28 ("drm/mediatek: Separate poweron/poweroff from enable/disable and define new funcs")
>> Signed-off-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>
>>
> Tested-by: Hsin-Yi Wang <hsinyi@...omium.org>
> 

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>