Re: [PATCH v3] drm/msm/dp: cleared DP_DOWNSPREAD_CTRL register before start link training
From: Dmitry Baryshkov
Date: Thu Sep 08 2022 - 12:07:38 EST
On Thu, 8 Sept 2022 at 18:38, Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx> wrote:
>
> DOWNSPREAD_CTRL (0x107) shall be cleared to 0 upon power-on reset or an
> upstream device disconnect. This patch will enforce this rule by always
> cleared DOWNSPREAD_CTRL register to 0 before start link training. At rare
> case that DP MSA timing parameters may be mis-interpreted by the sink
> which causes audio sampling rate be calculated wrongly and cause audio
> did not work at sink if DOWNSPREAD_CTRL register is not cleared to 0.
> This patch also make sure bring sink out of D3 power-down mode into D0
> (normal operation mode) successfully by retrying 3 times.
Split into three separate patches please.
--
With best wishes
Dmitry