[PATCH 3/6] drm: rcar-du: Fix LVDS stop sequence

[Laurent Pinchart]

Hi Tomi,

Thank you for the patch.

On Tue, Jan 17, 2023 at 03:51:51PM +0200, Tomi Valkeinen wrote:
> From: Koji Matsuoka <koji.matsuoka.xm at renesas.com>
> 
> According to H/W manual, LVDCR0 register must be cleared bit by bit when

s at H/W at the hardware/

> disabling LVDS.

I don't like this much, but I think I'll stop fighting :-)

> Signed-off-by: Koji Matsuoka <koji.matsuoka.xm at renesas.com>
> Signed-off-by: LUU HOAI <hoai.luu.ub at renesas.com>
> [tomi.valkeinen: simplified the code a bit]
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas at ideasonboard.com>
> ---
>  drivers/gpu/drm/rcar-du/rcar_lvds.c | 27 ++++++++++++++++++++++++++-
>  1 file changed, 26 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> index 674b727cdaa2..01800cef1c33 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> @@ -87,6 +87,11 @@ static void rcar_lvds_write(struct rcar_lvds *lvds, u32 reg, u32 data)
>  	iowrite32(data, lvds->mmio + reg);
>  }
>  
> +static u32 rcar_lvds_read(struct rcar_lvds *lvds, u32 reg)
> +{
> +	return ioread32(lvds->mmio + reg);
> +}

Could you please move read before write ?

> +
>  /* -----------------------------------------------------------------------------
>   * PLL Setup
>   */
> @@ -549,8 +554,28 @@ static void rcar_lvds_atomic_disable(struct drm_bridge *bridge,
>  				     struct drm_bridge_state *old_bridge_state)
>  {
>  	struct rcar_lvds *lvds = bridge_to_rcar_lvds(bridge);
> +	u32 lvdcr0;
> +
> +	lvdcr0 = rcar_lvds_read(lvds, LVDCR0);
> +
> +	lvdcr0 &= ~LVDCR0_LVRES;
> +	rcar_lvds_write(lvds, LVDCR0, lvdcr0);
> +
> +	if (lvds->info->quirks & RCAR_LVDS_QUIRK_GEN3_LVEN) {
> +		lvdcr0 &= ~LVDCR0_LVEN;
> +		rcar_lvds_write(lvds, LVDCR0, lvdcr0);
> +	}
> +
> +	if (lvds->info->quirks & RCAR_LVDS_QUIRK_PWD) {
> +		lvdcr0 &= ~LVDCR0_PWD;
> +		rcar_lvds_write(lvds, LVDCR0, lvdcr0);
> +	}
> +
> +	if (!(lvds->info->quirks & RCAR_LVDS_QUIRK_EXT_PLL)) {
> +		lvdcr0 &= ~LVDCR0_PLLON;
> +		rcar_lvds_write(lvds, LVDCR0, lvdcr0);
> +	}

This will leave LVDCR0_BEN and LVDCR0_LVEN on Gen2. Is that fine ?

>  
> -	rcar_lvds_write(lvds, LVDCR0, 0);
>  	rcar_lvds_write(lvds, LVDCR1, 0);
>  	rcar_lvds_write(lvds, LVDPLLCR, 0);
>  

-- 
Regards,

Laurent Pinchart