linux-kernel - Re: [PATCH v2] drm: mediatek: Fix display vblank timeout when disable dsi

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Date:   Mon, 19 Sep 2022 11:01:11 +0800
From:   Allen-KH Cheng <allen-kh.cheng@...iatek.com>
To:     Chun-Kuang Hu <chunkuang.hu@...nel.org>
CC:     Philipp Zabel <p.zabel@...gutronix.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Project_Global_Chrome_Upstream_Group 
        <Project_Global_Chrome_Upstream_Group@...iatek.com>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        Xinlei Lee (李昕磊) 
        <Xinlei.Lee@...iatek.com>
Subject: Re: [PATCH v2] drm: mediatek: Fix display vblank timeout when disable
 dsi

Hi CK,

We will test this fix on the mt8186/mt8183.
Maybe our fix is not necessary.

I appreciate your suggestion.

BRs,
Allen

On 9/18/22 12:32, Chun-Kuang Hu wrote:
> Hi, Allen:
> 
> Allen-KH Cheng <allen-kh.cheng@...iatek.com> 於 2022年9月14日 週三 晚上10:00寫道：
>>
>> From: Xinlei Lee <xinlei.lee@...iatek.com>
>>
>> Dsi is turned off at bridge.disable, causing crtc to wait for vblank
>> timeout. It is necessary to add count protection to turn off dsi and
>> turn off at post_disable.
> 
> If turn off dsi in post_disable(), you should turn on dsi in pre_enable().
> 
> There is another patch fix this problem [1], do you have any comment
> on that patch?
> 
> [1] http://lists.infradead.org/pipermail/linux-mediatek/2022-August/046713.html
> 
> Regards,
> Chun-Kuang.
> 
>>
>> Fixes: cde7e2e35c28 ("drm/mediatek: Separate poweron/poweroff from enable/disable and define new funcs")
>> Signed-off-by: Xinlei Lee <xinlei.lee@...iatek.com>
>> Co-developed-by: Allen-KH Cheng <allen-kh.cheng@...iatek.com>
>> Signed-off-by: Allen-KH Cheng <allen-kh.cheng@...iatek.com>
>> ---
>> Change in v1:
>>   * Rebase to kernel/git/chunkuang.hu/linux.git, mediatek-drm-fixes
>>     [Allen-KH Cheng <allen-kh.cheng@...iatek.com>]
>> ---
>> ---
>>  drivers/gpu/drm/mediatek/mtk_dsi.c | 15 ++++++---------
>>  1 file changed, 6 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
>> index 5b624e0f5b0a..e30f4244c001 100644
>> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
>> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
>> @@ -768,14 +768,6 @@ static void mtk_dsi_bridge_mode_set(struct drm_bridge *bridge,
>>         drm_display_mode_to_videomode(adjusted, &dsi->vm);
>>  }
>>
>> -static void mtk_dsi_bridge_atomic_disable(struct drm_bridge *bridge,
>> -                                         struct drm_bridge_state *old_bridge_state)
>> -{
>> -       struct mtk_dsi *dsi = bridge_to_dsi(bridge);
>> -
>> -       mtk_output_dsi_disable(dsi);
>> -}
>> -
>>  static void mtk_dsi_bridge_atomic_enable(struct drm_bridge *bridge,
>>                                          struct drm_bridge_state *old_bridge_state)
>>  {
>> @@ -803,13 +795,15 @@ static void mtk_dsi_bridge_atomic_post_disable(struct drm_bridge *bridge,
>>  {
>>         struct mtk_dsi *dsi = bridge_to_dsi(bridge);
>>
>> +       if (dsi->refcount == 1)
>> +               mtk_output_dsi_disable(dsi);
>> +
>>         mtk_dsi_poweroff(dsi);
>>  }
>>
>>  static const struct drm_bridge_funcs mtk_dsi_bridge_funcs = {
>>         .attach = mtk_dsi_bridge_attach,
>>         .atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
>> -       .atomic_disable = mtk_dsi_bridge_atomic_disable,
>>         .atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
>>         .atomic_enable = mtk_dsi_bridge_atomic_enable,
>>         .atomic_pre_enable = mtk_dsi_bridge_atomic_pre_enable,
>> @@ -829,6 +823,9 @@ void mtk_dsi_ddp_stop(struct device *dev)
>>  {
>>         struct mtk_dsi *dsi = dev_get_drvdata(dev);
>>
>> +       if (dsi->refcount == 1)
>> +               mtk_output_dsi_disable(dsi);
>> +
>>         mtk_dsi_poweroff(dsi);
>>  }
>>
>> --
>> 2.18.0
>>