linux-kernel - Re: [PATCH v4 24/78] drm/vc4: hvs: Make sure our channel is reset

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Date:   Tue, 28 Jul 2020 11:37:31 +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 24/78] drm/vc4: hvs: Make sure our channel is reset

Hi Maxime

On Wed, 8 Jul 2020 at 18:43, Maxime Ripard <maxime@...no.tech> wrote:
>
> In order to clear our intermediate FIFOs that might end up with a stale
> pixel, let's make sure our FIFO channel is reset everytime our channel is
> setup.

Minor nit pick: s/everytime/every time

> Signed-off-by: Maxime Ripard <maxime@...no.tech>

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

> ---
>  drivers/gpu/drm/vc4/vc4_hvs.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_hvs.c b/drivers/gpu/drm/vc4/vc4_hvs.c
> index c7de77afbf0a..64b9d72471ef 100644
> --- a/drivers/gpu/drm/vc4/vc4_hvs.c
> +++ b/drivers/gpu/drm/vc4/vc4_hvs.c
> @@ -205,6 +205,10 @@ static int vc4_hvs_init_channel(struct vc4_dev *vc4, struct drm_crtc *crtc,
>         u32 dispbkgndx;
>         u32 dispctrl;
>
> +       HVS_WRITE(SCALER_DISPCTRLX(chan), 0);
> +       HVS_WRITE(SCALER_DISPCTRLX(chan), SCALER_DISPCTRLX_RESET);
> +       HVS_WRITE(SCALER_DISPCTRLX(chan), 0);
> +
>         /* Turn on the scaler, which will wait for vstart to start
>          * compositing.
>          * When feeding the transposer, we should operate in oneshot
> --
> git-series 0.9.1