Re: [PATCH] drm/mediatek: mtk_dsi: Enable HS clock only at pre-enable

[CK Hu (胡俊光)]

On Tue, 2026-07-28 at 17:31 +0200, AngeloGioacchino Del Regno wrote:
> Commit 76255024cadb ("drm/mediatek: mtk_dsi: enable hs clock
> during pre-enable") rightfully moves the HS clock enablement to
> before atomic_enable(), but it's moving it to mtk_dsi_poweron(),
> which is not only called in the .atomic_pre_enable() callback
> for the DRM bridge, but also in the MediaTek DRM's .ddp_start()
> callback, which happens way before the bridge ones.
> 
> The HS clock enablement should be done at just the right time,
> otherwise some bridge chips (or some Display Driver ICs) may
> not work correctly: this is seen at least with a Parade DSI to
> eDP bridge (PS8640) on the MT8173 Elm Chromebook.
> 
> This resolves a regression that was seen on the aforementioned
> machine, which was happening only after a suspend-resume cycle.

Reviewed-by: CK Hu <ck.hu@xxxxxxxxxxxx>

> 
> Cc: <stable@xxxxxxxxxxxxxxx> # 7.1.x
> Fixes: 76255024cadb ("drm/mediatek: mtk_dsi: enable hs clock during pre-enable")
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> ---