linux-kernel - Re: [RESEND PATCH v3 4/6] drm/ingenic: Set DMA descriptor chain register when starting CRTC

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Date:   Fri, 29 Oct 2021 18:55:28 +0200
From:   Christophe Branchereau <cbranchereau@...il.com>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Sam Ravnborg <sam@...nborg.org>,
        "H . Nikolaus Schaller" <hns@...delico.com>,
        Paul Boddie <paul@...die.org.uk>, list@...ndingux.net,
        linux-mips@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH v3 4/6] drm/ingenic: Set DMA descriptor chain
 register when starting CRTC

Reviewed-by: Christophe Branchereau <cbranchereau@...il.com>

On Tue, Oct 26, 2021 at 8:13 PM Paul Cercueil <paul@...pouillou.net> wrote:
>
> Setting the DMA descriptor chain register in the probe function has been
> fine until now, because we only ever had one descriptor per foreground.
>
> As the driver will soon have real descriptor chains, and the DMA
> descriptor chain register updates itself to point to the current
> descriptor being processed, this register needs to be reset after a full
> modeset to point to the first descriptor of the chain.
>
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> ---
>  drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> index 5dbeca0f8f37..cbc76cede99e 100644
> --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> @@ -186,6 +186,10 @@ static void ingenic_drm_crtc_atomic_enable(struct drm_crtc *crtc,
>
>         regmap_write(priv->map, JZ_REG_LCD_STATE, 0);
>
> +       /* Set address of our DMA descriptor chain */
> +       regmap_write(priv->map, JZ_REG_LCD_DA0, dma_hwdesc_addr(priv, 0));
> +       regmap_write(priv->map, JZ_REG_LCD_DA1, dma_hwdesc_addr(priv, 1));
> +
>         regmap_update_bits(priv->map, JZ_REG_LCD_CTRL,
>                            JZ_LCD_CTRL_ENABLE | JZ_LCD_CTRL_DISABLE,
>                            JZ_LCD_CTRL_ENABLE);
> --
> 2.33.0
>