linux-kernel - Re: [PATCH 1/2] drm/msm/dp: postpone irq_hpd event during connection pending state

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Date:   Mon, 11 Jan 2021 11:55:18 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     Kuogee Hsieh <khsieh@...eaurora.org>,
        dri-devel@...ts.freedesktop.org, robdclark@...il.com,
        sean@...rly.run
Cc:     Kuogee Hsieh <khsieh@...eaurora.org>, tanmay@...eaurora.org,
        abhinavk@...eaurora.org, aravindh@...eaurora.org, airlied@...ux.ie,
        daniel@...ll.ch, linux-arm-msm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] drm/msm/dp: postpone irq_hpd event during connection pending state

Quoting Kuogee Hsieh (2021-01-07 12:30:24)
> irq_hpd event can only be executed at connected state. Therefore
> irq_hpd event should be postponed if it happened at connection
> pending state. This patch also make sure both link rate and lane

Why does it happen at connection pending state?

> are valid before start link training.

Can this part about link rate and lane being valid be split off into
another patch?

> 
> Signed-off-by: Kuogee Hsieh <khsieh@...eaurora.org>
> ---

Any fixes tag?

>  drivers/gpu/drm/msm/dp/dp_display.c |  7 +++++++
>  drivers/gpu/drm/msm/dp/dp_panel.c   | 12 +++++++++---
>  2 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 6e971d5..3bc7ed2 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -693,6 +693,13 @@ static int dp_irq_hpd_handle(struct dp_display_private *dp, u32 data)
>                 return 0;
>         }
>  
> +       if (state == ST_CONNECT_PENDING) {
> +               /* wait until ST_CONNECTED */
> +               dp_add_event(dp, EV_IRQ_HPD_INT, 0, 1); /* delay = 1 */
> +               mutex_unlock(&dp->event_mutex);
> +               return 0;
> +       }
> +
>         ret = dp_display_usbpd_attention_cb(&dp->pdev->dev);
>         if (ret == -ECONNRESET) { /* cable unplugged */
>                 dp->core_initialized = false;