[PATCH v3 5/5] drm: rcar-du: dsi: Fix VCLKSET write

[Laurent Pinchart]

Hi Tomi,

Thank you for the patch.

On Mon, Aug 22, 2022 at 05:34:01PM +0300, Tomi Valkeinen wrote:
> From: Tomi Valkeinen <tomi.valkeinen+renesas at ideasonboard.com>
> 
> rcar_mipi_dsi_startup() writes correct values to VCLKSET, but as it uses
> or-operation to add the new values to the current value in the register,
> it should first make sure the fields are cleared.
> 
> Do this by using rcar_mipi_dsi_write() to write the VCLKSET_CKEN bit to
> VCLKSET before the rest of the VCLKSET configuration.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas at ideasonboard.com>
> ---
>  drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> index 06250f2f3499..b60a6d4a5d46 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> @@ -412,9 +412,10 @@ static int rcar_mipi_dsi_startup(struct rcar_mipi_dsi *dsi,
>  			return ret;
>  	}
>  
> -	/* Enable DOT clock */
> -	vclkset = VCLKSET_CKEN;
> -	rcar_mipi_dsi_set(dsi, VCLKSET, vclkset);
> +	/* Clear VCLKSET and enable DOT clock */
> +	rcar_mipi_dsi_write(dsi, VCLKSET, VCLKSET_CKEN);
> +
> +	vclkset = 0;
>  
>  	if (dsi_format == 24)
>  		vclkset |= VCLKSET_BPP_24;

You can replace one more set() with a write():

diff --git a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
index 06250f2f3499..2744ea23e6f6 100644
--- a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
+++ b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
@@ -414,7 +414,7 @@ static int rcar_mipi_dsi_startup(struct rcar_mipi_dsi *dsi,

 	/* Enable DOT clock */
 	vclkset = VCLKSET_CKEN;
-	rcar_mipi_dsi_set(dsi, VCLKSET, vclkset);
+	rcar_mipi_dsi_write(dsi, VCLKSET, vclkset);

 	if (dsi_format == 24)
 		vclkset |= VCLKSET_BPP_24;
@@ -429,7 +429,7 @@ static int rcar_mipi_dsi_startup(struct rcar_mipi_dsi *dsi,
 	vclkset |= VCLKSET_COLOR_RGB | VCLKSET_DIV(setup_info.div)
 		|  VCLKSET_LANE(dsi->lanes - 1);

-	rcar_mipi_dsi_set(dsi, VCLKSET, vclkset);
+	rcar_mipi_dsi_write(dsi, VCLKSET, vclkset);

 	/* After setting VCLKSET register, enable VCLKEN */
 	rcar_mipi_dsi_set(dsi, VCLKEN, VCLKEN_CKEN);

I'll apply patches 1/5 to 4/5 to my tree already.

-- 
Regards,

Laurent Pinchart