linux-kernel - Re: [PATCH v1] drm/msm/dp: do not reinitialize phy unless retry during link training

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Message-ID: <CAE-0n53K538miRUbiW2OKwSeZ9juEPAcw42NDcD+T6M58hjnAA@mail.gmail.com>
Date:   Fri, 25 Aug 2023 17:15:25 -0500
From:   Stephen Boyd <swboyd@...omium.org>
To:     Kuogee Hsieh <quic_khsieh@...cinc.com>, agross@...nel.org,
        airlied@...il.com, andersson@...nel.org, daniel@...ll.ch,
        dianders@...omium.org, dmitry.baryshkov@...aro.org,
        marijn.suijten@...ainline.org, robdclark@...il.com,
        sean@...rly.run, vkoul@...nel.org
Cc:     quic_abhinavk@...cinc.com, quic_jesszhan@...cinc.com,
        quic_sbillaka@...cinc.com, freedreno@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] drm/msm/dp: do not reinitialize phy unless retry
 during link training

Quoting Kuogee Hsieh (2023-08-08 15:19:50)
> DP PHY re-initialization done using dp_ctrl_reinitialize_mainlink() will
> cause PLL unlocked initially and then PLL gets locked at the end of
> initialization. PLL_UNLOCKED interrupt will fire during this time if the
> interrupt mask is enabled.
> However currently DP driver link training implementation incorrectly
> re-initializes PHY unconditionally during link training as the PHY was
> already configured in dp_ctrl_enable_mainlink_clocks().
>
> Fix this by re-initializing the PHY only if the previous link training
> failed.
>
> [drm:dp_aux_isr] *ERROR* Unexpected DP AUX IRQ 0x01000000 when not busy
>
> Fixes: c943b4948b58 ("drm/msm/dp: add displayPort driver support")
> Closes: https://gitlab.freedesktop.org/drm/msm/-/issues/30
> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
> ---

Reviewed-by: Stephen Boyd <swboyd@...omium.org>