linux-kernel - Re: [PATCH] drm/bridge: it6505: Send DPCD SET

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Date:   Mon, 2 May 2022 16:37:48 +0200
From:   Robert Foss <robert.foss@...aro.org>
To:     Pin-Yen Lin <treapking@...omium.org>
Cc:     Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Allen Chen <allen.chen@....com.tw>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Hermes Wu <hermes.wu@....com.tw>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/bridge: it6505: Send DPCD SET_POWER to downstream

On Mon, 25 Apr 2022 at 15:44, Pin-Yen Lin <treapking@...omium.org> wrote:
>
> Send DPCD SET_POWER command to downstream in .atomic_disable to make the
> downstream monitor enter the power down mode, so the device suspend won't
> be affected.
>
> Fixes: b5c84a9edcd418 ("drm/bridge: add it6505 driver")
> Signed-off-by: Pin-Yen Lin <treapking@...omium.org>
> ---
>
>  drivers/gpu/drm/bridge/ite-it6505.c | 29 ++++++++++++++++++-----------
>  1 file changed, 18 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index 8fed30df08b0..4b673c4792d7 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -737,8 +737,9 @@ static int it6505_drm_dp_link_probe(struct drm_dp_aux *aux,
>         return 0;
>  }
>
> -static int it6505_drm_dp_link_power_up(struct drm_dp_aux *aux,
> -                                      struct it6505_drm_dp_link *link)
> +static int it6505_drm_dp_link_set_power(struct drm_dp_aux *aux,
> +                                       struct it6505_drm_dp_link *link,
> +                                       u8 mode)
>  {
>         u8 value;
>         int err;
> @@ -752,18 +753,20 @@ static int it6505_drm_dp_link_power_up(struct drm_dp_aux *aux,
>                 return err;
>
>         value &= ~DP_SET_POWER_MASK;
> -       value |= DP_SET_POWER_D0;
> +       value |= mode;
>
>         err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
>         if (err < 0)
>                 return err;
>
> -       /*
> -        * According to the DP 1.1 specification, a "Sink Device must exit the
> -        * power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink
> -        * Control Field" (register 0x600).
> -        */
> -       usleep_range(1000, 2000);
> +       if (mode == DP_SET_POWER_D0) {
> +               /*
> +                * According to the DP 1.1 specification, a "Sink Device must
> +                * exit the power saving state within 1 ms" (Section 2.5.3.1,
> +                * Table 5-52, "Sink Control Field" (register 0x600).
> +                */
> +               usleep_range(1000, 2000);
> +       }
>
>         return 0;
>  }
> @@ -2624,7 +2627,8 @@ static enum drm_connector_status it6505_detect(struct it6505 *it6505)
>         if (it6505_get_sink_hpd_status(it6505)) {
>                 it6505_aux_on(it6505);
>                 it6505_drm_dp_link_probe(&it6505->aux, &it6505->link);
> -               it6505_drm_dp_link_power_up(&it6505->aux, &it6505->link);
> +               it6505_drm_dp_link_set_power(&it6505->aux, &it6505->link,
> +                                            DP_SET_POWER_D0);
>                 it6505->auto_train_retry = AUTO_TRAIN_RETRY;
>
>                 if (it6505->dpcd[0] == 0) {
> @@ -2960,8 +2964,11 @@ static void it6505_bridge_atomic_disable(struct drm_bridge *bridge,
>
>         DRM_DEV_DEBUG_DRIVER(dev, "start");
>
> -       if (it6505->powered)
> +       if (it6505->powered) {
>                 it6505_video_disable(it6505);
> +               it6505_drm_dp_link_set_power(&it6505->aux, &it6505->link,
> +                                            DP_SET_POWER_D3);
> +       }
>  }
>
>  static enum drm_connector_status
> --
> 2.36.0.rc2.479.g8af0fa9b8e-goog
>

Reviewed-by: Robert Foss <robert.foss@...aro.org>

Applied to drm-misc-next.