linux-kernel - Re: [PATCH v3 1/2] drm/msm/dp: handle irq_hpd with sink

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Date:   Fri, 14 May 2021 02:03:37 -0500
From:   Stephen Boyd <swboyd@...omium.org>
To:     Kuogee Hsieh <khsieh@...eaurora.org>, agross@...nel.org,
        bjorn.andersson@...aro.org, robdclark@...il.com, sean@...rly.run,
        vkoul@...nel.org
Cc:     abhinavk@...eaurora.org, aravindh@...eaurora.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/2] drm/msm/dp: handle irq_hpd with sink_count = 0 correctly

Quoting Kuogee Hsieh (2021-05-12 16:29:59)
> irq_hpd interrupt should be handled after dongle plugged in and
> before dongle unplugged. Hence irq_hpd interrupt is enabled at
> the end of the plugin handle and disabled at the beginning of
> unplugged handle. Current irq_hpd with sink_count = 0 is wrongly
> handled same as the dongle unplugged which tears down the mainlink
> and disables the phy. This patch fixes this problem by only tearing
> down the mainlink but keeping phy enabled at irq_hpd with
> sink_count = 0 handle so that next irq_hpe with sink_count =1 can be

s/irq_hpe/irq/hpd/

> handled by setup mainlink only.
>
> Changes in v2:
> -- add ctrl->phy_Power_count
>
> Changes in v3:
> -- del ctrl->phy_Power_count
> -- add phy_power_off to dp_ctrl_off_link_stream()
>
> Signed-off-by: Kuogee Hsieh <khsieh@...eaurora.org>
> ---
>  drivers/gpu/drm/msm/dp/dp_catalog.c |  5 ++--
>  drivers/gpu/drm/msm/dp/dp_ctrl.c    | 54 +++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/msm/dp/dp_ctrl.h    |  2 ++
>  drivers/gpu/drm/msm/dp/dp_display.c | 46 ++++++++++++++++++++++++-------
>  4 files changed, 94 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_catalog.c b/drivers/gpu/drm/msm/dp/dp_catalog.c
> index b1a9b1b..f4f53f2 100644
> --- a/drivers/gpu/drm/msm/dp/dp_catalog.c
> +++ b/drivers/gpu/drm/msm/dp/dp_catalog.c
> @@ -582,10 +582,9 @@ void dp_catalog_ctrl_hpd_config(struct dp_catalog *dp_catalog)
>
>         u32 reftimer = dp_read_aux(catalog, REG_DP_DP_HPD_REFTIMER);
>
> -       /* enable HPD interrupts */
> +       /* enable HPD plug and unplug interrupts */
>         dp_catalog_hpd_config_intr(dp_catalog,
> -               DP_DP_HPD_PLUG_INT_MASK | DP_DP_IRQ_HPD_INT_MASK
> -               | DP_DP_HPD_UNPLUG_INT_MASK | DP_DP_HPD_REPLUG_INT_MASK, true);
> +               DP_DP_HPD_PLUG_INT_MASK | DP_DP_HPD_UNPLUG_INT_MASK, true);
>
>         /* Configure REFTIMER and enable it */
>         reftimer |= DP_DP_HPD_REFTIMER_ENABLE;
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> index 8d59eb9..41c122c 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -1811,6 +1811,60 @@ int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl)
>         return ret;
>  }
>
> +int dp_ctrl_off_link_stream(struct dp_ctrl *dp_ctrl)
> +{
> +       struct dp_ctrl_private *ctrl;
> +       struct dp_io *dp_io;
> +       struct phy *phy;
> +       int ret = 0;

Please don't assign ret and then reassign it without testing it first.

> +
> +       if (!dp_ctrl)

Does this ever happen?

> +               return -EINVAL;
> +
> +       ctrl = container_of(dp_ctrl, struct dp_ctrl_private, dp_ctrl);
> +       dp_io = &ctrl->parser->io;
> +       phy = dp_io->phy;
> +
> +       dp_catalog_ctrl_mainlink_ctrl(ctrl->catalog, false);
> +
> +       ret = dp_power_clk_enable(ctrl->power, DP_STREAM_PM, false);
> +       if (ret)
> +               DRM_ERROR("Failed to disable pixel clocks. ret=%d\n", ret);

Why do we continue instead of returning with a failure?

> +
> +       ret = dp_power_clk_enable(ctrl->power, DP_CTRL_PM, false);
> +       if (ret)
> +               DRM_ERROR("Failed to disable link clocks. ret=%d\n", ret);

Same, why do we continue?

> +
> +       phy_power_off(phy);
> +       phy_exit(phy);
> +
> +       /* aux channel down, reinit phy */

So we need to call exit/init to reinitialize the phy? I wonder if there
could be some phy_reinit() function that combines those.

> +       phy_init(phy);
> +
> +       DRM_DEBUG_DP("DP off link/stream done\n");
> +       return ret;

Except here we return with a failure.

> +}
> +
> +void dp_ctrl_off_phy(struct dp_ctrl *dp_ctrl)
> +{
> +       struct dp_ctrl_private *ctrl;
> +       struct dp_io *dp_io;
> +       struct phy *phy;
> +
> +       if (!dp_ctrl)

Does this ever happen?

> +               return;
> +
> +       ctrl = container_of(dp_ctrl, struct dp_ctrl_private, dp_ctrl);
> +       dp_io = &ctrl->parser->io;
> +       phy = dp_io->phy;
> +
> +       dp_catalog_ctrl_reset(ctrl->catalog);
> +
> +       phy_exit(phy);
> +
> +       DRM_DEBUG_DP("DP off phy done\n");
> +}
> +
>  int dp_ctrl_off(struct dp_ctrl *dp_ctrl)
>  {
>         struct dp_ctrl_private *ctrl;