linux-kernel - Re: [PATCH v6] drm/msm/dp: Always clear mask bits to disable interrupts at dp_ctrl_reset_irq

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Date:   Tue, 17 May 2022 01:25:53 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Kuogee Hsieh <quic_khsieh@...cinc.com>, agross@...nel.org,
        airlied@...ux.ie, bjorn.andersson@...aro.org, daniel@...ll.ch,
        dianders@...omium.org, dmitry.baryshkov@...aro.org,
        robdclark@...il.com, sean@...rly.run, vkoul@...nel.org
Cc:     quic_abhinavk@...cinc.com, quic_aravindh@...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 v6] drm/msm/dp: Always clear mask bits to disable
 interrupts at dp_ctrl_reset_irq_ctrl()

Quoting Kuogee Hsieh (2022-05-12 12:43:18)
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> index af7a80c..f3e333e 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -1389,8 +1389,13 @@ void dp_ctrl_reset_irq_ctrl(struct dp_ctrl *dp_ctrl, bool enable)
>
>         dp_catalog_ctrl_reset(ctrl->catalog);
>
> -       if (enable)
> -               dp_catalog_ctrl_enable_irq(ctrl->catalog, enable);
> +       /*
> +        * all dp controller programmable registers will not
> +        * be reset to default value after DP_SW_RESET
> +        * therefore interrupt mask bits have to be updated
> +        * to enable/disable interrupts
> +        */
> +       dp_catalog_ctrl_enable_irq(ctrl->catalog, enable);

I think Dmitry requested that this part be split off to a different
patch. It's fixing the call to dp_ctrl_reset_irq_ctrl() for the disable
case.

>  }
>
>  void dp_ctrl_phy_init(struct dp_ctrl *dp_ctrl)
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index c388323..ab691aa 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -98,6 +98,8 @@ struct dp_display_private {
>         struct dp_ctrl    *ctrl;
>         struct dp_debug   *debug;
>
> +       bool suspended;
> +

Can we not have this flag? I also don't understand how this patch waits
for the event queue to drain. There are now multiple places we check to
see if we've suspended, but is it even possible to be in those places
during suspend? What is wrong with moving to an irq thread? Is it
because we want to wait for a modeset (EV_USER_NOTIFICATION)?

>         struct dp_usbpd_cb usbpd_cb;
>         struct dp_display_mode dp_mode;
>         struct msm_dp dp_display;