linux-kernel - Re: [PATCH 2/2] drm/rockchip: analogix_dp: Refuse to enable PSR if panel doesn't support it

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Date:   Tue, 27 Sep 2016 09:28:58 -0400
From:   Sean Paul <seanpaul@...omium.org>
To:     Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Yakir Yang <ykk@...k-chips.com>,
        Archit Taneja <architt@...eaurora.org>,
        Mark Yao <mark.yao@...k-chips.com>,
        David Airlie <airlied@...ux.ie>,
        Heiko Stuebner <heiko@...ech.de>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Linux ARM Kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH 2/2] drm/rockchip: analogix_dp: Refuse to enable PSR if
 panel doesn't support it

On Fri, Sep 23, 2016 at 10:06 AM, Tomeu Vizoso
<tomeu.vizoso@...labora.com> wrote:
> There's no point in enabling PSR when the panel doesn't support it.
>
> This also avoids a problem when PSR gets enabled when a CRTC is being
> disabled, because sometimes in that situation the DSP_HOLD_VALID_INTR
> interrupt on which we wait will never arrive. This was observed on
> RK3288 with a panel without PSR (veyron-jaq Chromebook).
>
> It's very easy to reproduce by running the kms_rmfb test in IGT a few
> times.
>
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>

Thanks for digging into this.

Reviewed-by: Sean Paul <seanpaul@...omium.org>



> Cc: Sean Paul <seanpaul@...omium.org>
> Cc: Yakir Yang <ykk@...k-chips.com>
> Cc: Archit Taneja <architt@...eaurora.org>
> ---
>  drivers/gpu/drm/rockchip/analogix_dp-rockchip.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
> index e83be157cc2a..8548e8271639 100644
> --- a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
> +++ b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
> @@ -85,6 +85,9 @@ static void analogix_dp_psr_set(struct drm_encoder *encoder, bool enabled)
>         struct rockchip_dp_device *dp = to_dp(encoder);
>         unsigned long flags;
>
> +       if (!analogix_dp_psr_supported(dp->dev))
> +               return;
> +
>         dev_dbg(dp->dev, "%s PSR...\n", enabled ? "Entry" : "Exit");
>
>         spin_lock_irqsave(&dp->psr_lock, flags);
> --
> 2.7.4
>