linux-kernel - Re: [PATCH v4 27/78] drm/vc4: crtc: Move HVS channel init before the PV initialisation

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Message-ID: <CAPY8ntDeMAuDb1ZWj59+14ZQVqDjM7X+E312Lymm0P8LHFx0Yg@mail.gmail.com>
Date:   Tue, 28 Jul 2020 11:40:37 +0100
From:   Dave Stevenson <dave.stevenson@...pberrypi.com>
To:     Maxime Ripard <maxime@...no.tech>
Cc:     Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Eric Anholt <eric@...olt.net>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        linux-rpi-kernel@...ts.infradead.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-arm-kernel@...ts.infradead.org,
        LKML <linux-kernel@...r.kernel.org>,
        Tim Gover <tim.gover@...pberrypi.com>,
        Phil Elwell <phil@...pberrypi.com>
Subject: Re: [PATCH v4 27/78] drm/vc4: crtc: Move HVS channel init before the
 PV initialisation

Hi Maxime

On Wed, 8 Jul 2020 at 18:43, Maxime Ripard <maxime@...no.tech> wrote:
>
> In order to avoid stale pixels getting stuck in an intermediate FIFO
> between the HVS and the pixelvalve on BCM2711, we need to configure the HVS
> channel before the pixelvalve is reset and configured.
>
> Signed-off-by: Maxime Ripard <maxime@...no.tech>

Reviewed-by: Dave Stevenson <dave.stevenson@...pberrypi.com>

> ---
>  drivers/gpu/drm/vc4/vc4_crtc.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c
> index 2c5ff45dc315..b7b0e19e2fe1 100644
> --- a/drivers/gpu/drm/vc4/vc4_crtc.c
> +++ b/drivers/gpu/drm/vc4/vc4_crtc.c
> @@ -427,10 +427,6 @@ static void vc4_crtc_atomic_enable(struct drm_crtc *crtc,
>
>         require_hvs_enabled(dev);
>
> -       vc4_crtc_config_pv(crtc);
> -
> -       CRTC_WRITE(PV_CONTROL, CRTC_READ(PV_CONTROL) | PV_CONTROL_EN);
> -
>         /* Enable vblank irq handling before crtc is started otherwise
>          * drm_crtc_get_vblank() fails in vc4_crtc_update_dlist().
>          */
> @@ -438,6 +434,10 @@ static void vc4_crtc_atomic_enable(struct drm_crtc *crtc,
>
>         vc4_hvs_atomic_enable(crtc, old_state);
>
> +       vc4_crtc_config_pv(crtc);
> +
> +       CRTC_WRITE(PV_CONTROL, CRTC_READ(PV_CONTROL) | PV_CONTROL_EN);
> +
>         /* When feeding the transposer block the pixelvalve is unneeded and
>          * should not be enabled.
>          */
> --
> git-series 0.9.1