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References: <20221013110411.1674359-1-treapking@chromium.org> <20221013110411.1674359-3-treapking@chromium.org>
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From:   Robert Foss <robert.foss@linaro.org>
Date:   Mon, 24 Oct 2022 09:56:15 +0200
Message-ID: <CAG3jFyskXfbX=rTye9ygT36kKmqJRr0rO1eQrKSr1V7hOHxDcA@mail.gmail.com>
Subject: Re: [PATCH v2 2/3] drm/bridge: it6505: Setup links in it6505_irq_hpd
To:     Pin-yen Lin <treapking@chromium.org>
Cc:     Andrzej Hajda <andrzej.hajda@intel.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
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Precedence: bulk

On Thu, 13 Oct 2022 at 13:04, Pin-yen Lin <treapking@chromium.org> wrote:
>
> Move the DPCD read and link setup steps to HPD IRQ handler to remove
> an unnecessary dependency between .detect callback and the HPD IRQ
> handler before registering it6505 as a DRM bridge. This is safe because
> there is always a .detect call after each HPD IRQ handler triggered by
> the drm_helper_hpd_irq_event call.
>
> Signed-off-by: Pin-yen Lin <treapking@chromium.org>
> ---
>
> Changes in v2:
> - Remove redundant spaces in it6505_detect
> - Read sink count in it6505_irq_hpd
>
>  drivers/gpu/drm/bridge/ite-it6505.c | 80 +++++++++++++----------------
>  1 file changed, 35 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index f7f6c3e20fae..4b6061272599 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -725,28 +725,6 @@ static void it6505_calc_video_info(struct it6505 *it6505)
>                              DRM_MODE_ARG(&it6505->video_info));
>  }
>
> -static int it6505_drm_dp_link_probe(struct drm_dp_aux *aux,
> -                                   struct it6505_drm_dp_link *link)
> -{
> -       u8 values[3];
> -       int err;
> -
> -       memset(link, 0, sizeof(*link));
> -
> -       err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values));
> -       if (err < 0)
> -               return err;
> -
> -       link->revision = values[0];
> -       link->rate = drm_dp_bw_code_to_link_rate(values[1]);
> -       link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK;
> -
> -       if (values[2] & DP_ENHANCED_FRAME_CAP)
> -               link->capabilities = DP_ENHANCED_FRAME_CAP;
> -
> -       return 0;
> -}
> -
>  static int it6505_drm_dp_link_set_power(struct drm_dp_aux *aux,
>                                         struct it6505_drm_dp_link *link,
>                                         u8 mode)
> @@ -1456,11 +1434,19 @@ static void it6505_parse_link_capabilities(struct it6505 *it6505)
>         int bcaps;
>
>         if (it6505->dpcd[0] == 0) {
> -               it6505_aux_on(it6505);
> -               it6505_get_dpcd(it6505, DP_DPCD_REV, it6505->dpcd,
> -                               ARRAY_SIZE(it6505->dpcd));
> +               dev_err(dev, "DPCD is not initialized");
> +               return;
>         }
>
> +       memset(link, 0, sizeof(*link));
> +
> +       link->revision = it6505->dpcd[0];
> +       link->rate = drm_dp_bw_code_to_link_rate(it6505->dpcd[1]);
> +       link->num_lanes = it6505->dpcd[2] & DP_MAX_LANE_COUNT_MASK;
> +
> +       if (it6505->dpcd[2] & DP_ENHANCED_FRAME_CAP)
> +               link->capabilities = DP_ENHANCED_FRAME_CAP;
> +
>         DRM_DEV_DEBUG_DRIVER(dev, "DPCD Rev.: %d.%d",
>                              link->revision >> 4, link->revision & 0x0F);
>
> @@ -2323,19 +2309,32 @@ static int it6505_process_hpd_irq(struct it6505 *it6505)
>  static void it6505_irq_hpd(struct it6505 *it6505)
>  {
>         struct device *dev = &it6505->client->dev;
> +       int dp_sink_count;
>
>         it6505->hpd_state = it6505_get_sink_hpd_status(it6505);
>         DRM_DEV_DEBUG_DRIVER(dev, "hpd change interrupt, change to %s",
>                              it6505->hpd_state ? "high" : "low");
>
> -       if (it6505->bridge.dev)
> -               drm_helper_hpd_irq_event(it6505->bridge.dev);
> -       DRM_DEV_DEBUG_DRIVER(dev, "it6505->sink_count: %d",
> -                            it6505->sink_count);
> -
>         if (it6505->hpd_state) {
>                 wait_for_completion_timeout(&it6505->wait_edid_complete,
>                                             msecs_to_jiffies(6000));
> +               it6505_aux_on(it6505);
> +               if (it6505->dpcd[0] == 0) {
> +                       it6505_get_dpcd(it6505, DP_DPCD_REV, it6505->dpcd,
> +                                       ARRAY_SIZE(it6505->dpcd));
> +                       it6505_variable_config(it6505);
> +                       it6505_parse_link_capabilities(it6505);
> +               }
> +               it6505->auto_train_retry = AUTO_TRAIN_RETRY;
> +
> +               it6505_drm_dp_link_set_power(&it6505->aux, &it6505->link,
> +                                            DP_SET_POWER_D0);
> +               dp_sink_count = it6505_dpcd_read(it6505, DP_SINK_COUNT);
> +               it6505->sink_count = DP_GET_SINK_COUNT(dp_sink_count);
> +
> +               DRM_DEV_DEBUG_DRIVER(dev, "it6505->sink_count: %d",
> +                                    it6505->sink_count);
> +
>                 it6505_lane_termination_on(it6505);
>                 it6505_lane_power_on(it6505);
>
> @@ -2363,6 +2362,9 @@ static void it6505_irq_hpd(struct it6505 *it6505)
>                 it6505_lane_off(it6505);
>                 it6505_link_reset_step_train(it6505);
>         }
> +
> +       if (it6505->bridge.dev)
> +               drm_helper_hpd_irq_event(it6505->bridge.dev);
>  }
>
>  static void it6505_irq_hpd_irq(struct it6505 *it6505)
> @@ -2625,26 +2627,14 @@ static enum drm_connector_status it6505_detect(struct it6505 *it6505)
>                 goto unlock;
>
>         if (it6505->enable_drv_hold) {
> -               status = it6505_get_sink_hpd_status(it6505) ?
> -                                       connector_status_connected :
> -                                       connector_status_disconnected;
> +               status = it6505->hpd_state ? connector_status_connected :
> +                                            connector_status_disconnected;
>                 goto unlock;
>         }
>
> -       if (it6505_get_sink_hpd_status(it6505)) {
> -               it6505_aux_on(it6505);
> -               it6505_drm_dp_link_probe(&it6505->aux, &it6505->link);
> +       if (it6505->hpd_state) {
>                 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) {
> -                       it6505_get_dpcd(it6505, DP_DPCD_REV, it6505->dpcd,
> -                                       ARRAY_SIZE(it6505->dpcd));
> -                       it6505_variable_config(it6505);
> -                       it6505_parse_link_capabilities(it6505);
> -               }
> -
>                 dp_sink_count = it6505_dpcd_read(it6505, DP_SINK_COUNT);
>                 it6505->sink_count = DP_GET_SINK_COUNT(dp_sink_count);
>                 DRM_DEV_DEBUG_DRIVER(dev, "it6505->sink_count:%d branch:%d",
> --
> 2.38.0.rc1.362.ged0d419d3c-goog
>

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