[PATCH 2/3] drm: rcar-du: Fix r8a779a0 color issue.

[Laurent Pinchart]

Hi Tomi,

Thank you for the patch.

On Wed, Aug 17, 2022 at 04:28:02PM +0300, Tomi Valkeinen wrote:
> From: Tomi Valkeinen <tomi.valkeinen+renesas at ideasonboard.com>
> 
> The rcar DU driver on r8a779a0 has a bug causing some specific colors
> getting converted to transparent colors, which then (usually) show as
> black pixels on the screen.
> 
> The reason seems to be that the driver sets PnMR_SPIM_ALP bit in
> PnMR.SPIM field, which is an illegal setting on r8a779a0. The
> PnMR_SPIM_EOR bit also illegal.
> 
> Add a new feature flag for this (lack of a) feature and make sure the
> bits are zero on r8a779a0.

Good catch !

> Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas at ideasonboard.com>
> ---
>  drivers/gpu/drm/rcar-du/rcar_du_drv.c   |  3 ++-
>  drivers/gpu/drm/rcar-du/rcar_du_drv.h   |  1 +
>  drivers/gpu/drm/rcar-du/rcar_du_plane.c | 16 +++++++++++++---
>  3 files changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.c b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> index 541c202c993a..a2776f1d6f2c 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> @@ -506,7 +506,8 @@ static const struct rcar_du_device_info rcar_du_r8a7799x_info = {
>  static const struct rcar_du_device_info rcar_du_r8a779a0_info = {
>  	.gen = 3,
>  	.features = RCAR_DU_FEATURE_CRTC_IRQ
> -		  | RCAR_DU_FEATURE_VSP1_SOURCE,
> +		  | RCAR_DU_FEATURE_VSP1_SOURCE
> +		  | RCAR_DU_FEATURE_NO_BLENDING,
>  	.channels_mask = BIT(1) | BIT(0),
>  	.routes = {
>  		/* R8A779A0 has two MIPI DSI outputs. */
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.h b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> index bfad7775d9a1..712389c7b3d0 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> @@ -31,6 +31,7 @@ struct rcar_du_device;
>  #define RCAR_DU_FEATURE_VSP1_SOURCE	BIT(2)	/* Has inputs from VSP1 */
>  #define RCAR_DU_FEATURE_INTERLACED	BIT(3)	/* HW supports interlaced */
>  #define RCAR_DU_FEATURE_TVM_SYNC	BIT(4)	/* Has TV switch/sync modes */
> +#define RCAR_DU_FEATURE_NO_BLENDING	BIT(5)	/* PnMR.SPIM does not have ALP nor EOR bits */
>  
>  #define RCAR_DU_QUIRK_ALIGN_128B	BIT(0)	/* Align pitches to 128 bytes */
>  
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_plane.c b/drivers/gpu/drm/rcar-du/rcar_du_plane.c
> index 9e1f0cbbf642..2103816807cc 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_plane.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_plane.c
> @@ -506,8 +506,19 @@ static void rcar_du_plane_setup_format_gen3(struct rcar_du_group *rgrp,
>  					    unsigned int index,
>  					    const struct rcar_du_plane_state *state)
>  {
> -	rcar_du_plane_write(rgrp, index, PnMR,
> -			    PnMR_SPIM_TP_OFF | state->format->pnmr);
> +	struct rcar_du_device *rcdu = rgrp->dev;
> +	u32 pnmr;
> +
> +	pnmr = state->format->pnmr;
> +
> +	if (rcdu->info->features & RCAR_DU_FEATURE_NO_BLENDING) {
> +		/* No blending. ALP and EOR are not supported */
> +		pnmr &= ~(PnMR_SPIM_ALP | PnMR_SPIM_EOR);
> +	}
> +
> +	pnmr |= PnMR_SPIM_TP_OFF;

I'd combine this with the initial pnmr assignment. I can handle this
when applying, no need to resubmit.

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

> +
> +	rcar_du_plane_write(rgrp, index, PnMR, pnmr);
>  
>  	rcar_du_plane_write(rgrp, index, PnDDCR4,
>  			    state->format->edf | PnDDCR4_CODE);
> @@ -521,7 +532,6 @@ static void rcar_du_plane_setup_format_gen3(struct rcar_du_group *rgrp,
>  	 * register to 0 to avoid this.
>  	 */
>  
> -	/* TODO: Check if alpha-blending should be disabled in PnMR. */
>  	rcar_du_plane_write(rgrp, index, PnALPHAR, 0);
>  }

-- 
Regards,

Laurent Pinchart