drm: rcar-du: Extend CMM HDSE documentation

[PATCH] drm: rcar-du: Extend CMM HDSE documentation

Posted by Kieran Bingham 4 years, 2 months ago

When the CMM is enabled, the HDSE offset is further adjusted to
compensate for consumed pixels.

Explain this further, with an extra comment at the point the offset is
adjusted.

Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
---
 drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
index f361a604337f..23e1aedf8dc0 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
@@ -300,6 +300,11 @@ static void rcar_du_crtc_set_display_timing(struct rcar_du_crtc *rcrtc)
 	     | DSMR_DIPM_DISP | DSMR_CSPM;
 	rcar_du_crtc_write(rcrtc, DSMR, dsmr);
 
+	/*
+	 * When the CMM is enabled, an additional offset of 25 pixels must be
+	 * subtracted from the HDS (horizontal display start) and HDE
+	 * (horizontal display end) registers.
+	 */
 	hdse_offset = 19;
 	if (rcrtc->group->cmms_mask & BIT(rcrtc->index % 2))
 		hdse_offset += 25;
-- 
2.32.0

Re: [PATCH] drm: rcar-du: Extend CMM HDSE documentation

Posted by Laurent Pinchart 4 years, 2 months ago

Hi Kieran,

Thank you for the patch.

On Sat, Apr 09, 2022 at 07:57:06PM +0100, Kieran Bingham wrote:
> When the CMM is enabled, the HDSE offset is further adjusted to
> compensate for consumed pixels.
> 
> Explain this further, with an extra comment at the point the offset is
> adjusted.
> 
> Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> index f361a604337f..23e1aedf8dc0 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> @@ -300,6 +300,11 @@ static void rcar_du_crtc_set_display_timing(struct rcar_du_crtc *rcrtc)
>  	     | DSMR_DIPM_DISP | DSMR_CSPM;
>  	rcar_du_crtc_write(rcrtc, DSMR, dsmr);
>  
> +	/*
> +	 * When the CMM is enabled, an additional offset of 25 pixels must be
> +	 * subtracted from the HDS (horizontal display start) and HDE
> +	 * (horizontal display end) registers.
> +	 */
>  	hdse_offset = 19;
>  	if (rcrtc->group->cmms_mask & BIT(rcrtc->index % 2))
>  		hdse_offset += 25;

-- 
Regards,

Laurent Pinchart