Re: [PATCH 4/7] drm/omap: Implement CTM property for CRTC using OVL managers CPR matrix

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Tomi,

Thank you for the patch.

On Mon, Sep 02, 2019 at 03:53:56PM +0300, Tomi Valkeinen wrote:
> From: Jyri Sarha <jsarha@ti.com>
> 
> Implement CTM color management property for OMAP CRTC using DSS
> overlay manager's Color Phase Rotation matrix. The CPR matrix does not
> exactly match the CTM property documentation. On DSS the CPR matrix is
> applied after gamma table look up. However, it seems stupid to add a
> custom property just for that.

In that case the DRM documentation should be updated to mention that
both options are allowed.

> Signed-off-by: Jyri Sarha <jsarha@ti.com>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> ---
>  drivers/gpu/drm/omapdrm/omap_crtc.c | 39 +++++++++++++++++++++++++++--
>  1 file changed, 37 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/omapdrm/omap_crtc.c b/drivers/gpu/drm/omapdrm/omap_crtc.c
> index 3c5ddbf30e97..d63213dd7d83 100644
> --- a/drivers/gpu/drm/omapdrm/omap_crtc.c
> +++ b/drivers/gpu/drm/omapdrm/omap_crtc.c
> @@ -391,6 +391,32 @@ static void omap_crtc_manual_display_update(struct work_struct *data)
>  	}
>  }
>  
> +static s16 omap_crtc_S31_32_to_s2_8(s64 coef)
> +{
> +	uint64_t sign_bit = 1ULL << 63;
> +	uint64_t cbits = (uint64_t) coef;

s/uint64_t/u64/ for both lines as we're dealing with kernel code. And
there's no need for a space before coef.

> +	s16 ret = clamp_val(((cbits & ~sign_bit) >> 24), 0, 0x1FF);
> +
> +	if (cbits & sign_bit)
> +		ret = -ret;
> +
> +	return ret;

Can't this be simplified to 

	s16 ret = (coef >> 24) & 0x1ff;

	return coef < 0 ? -ret : ret;

> +}
> +
> +static void omap_crtc_cpr_coefs_from_ctm(const struct drm_color_ctm *ctm,
> +					 struct omap_dss_cpr_coefs *cpr)
> +{
> +	cpr->rr = omap_crtc_S31_32_to_s2_8(ctm->matrix[0]);
> +	cpr->rg = omap_crtc_S31_32_to_s2_8(ctm->matrix[1]);
> +	cpr->rb = omap_crtc_S31_32_to_s2_8(ctm->matrix[2]);
> +	cpr->gr = omap_crtc_S31_32_to_s2_8(ctm->matrix[3]);
> +	cpr->gg = omap_crtc_S31_32_to_s2_8(ctm->matrix[4]);
> +	cpr->gb = omap_crtc_S31_32_to_s2_8(ctm->matrix[5]);
> +	cpr->br = omap_crtc_S31_32_to_s2_8(ctm->matrix[6]);
> +	cpr->bg = omap_crtc_S31_32_to_s2_8(ctm->matrix[7]);
> +	cpr->bb = omap_crtc_S31_32_to_s2_8(ctm->matrix[8]);
> +}
> +
>  static void omap_crtc_write_crtc_properties(struct drm_crtc *crtc)
>  {
>  	struct omap_drm_private *priv = crtc->dev->dev_private;
> @@ -402,7 +428,16 @@ static void omap_crtc_write_crtc_properties(struct drm_crtc *crtc)
>  	info.default_color = 0x000000;
>  	info.trans_enabled = false;
>  	info.partial_alpha_enabled = false;
> -	info.cpr_enable = false;
> +
> +	if (crtc->state->ctm) {
> +		struct drm_color_ctm *ctm =
> +			(struct drm_color_ctm *) crtc->state->ctm->data;
> +
> +		info.cpr_enable = true;
> +		omap_crtc_cpr_coefs_from_ctm(ctm, &info.cpr_coefs);

As an optimisation it would be nice to only write the coefficients when
they actually change. That could be implemented on top of this series.

> +	} else {
> +		info.cpr_enable = false;
> +	}
>  
>  	priv->dispc_ops->mgr_setup(priv->dispc, omap_crtc->channel, &info);
>  }
> @@ -836,7 +871,7 @@ struct drm_crtc *omap_crtc_init(struct drm_device *dev,
>  	if (priv->dispc_ops->mgr_gamma_size(priv->dispc, channel)) {
>  		unsigned int gamma_lut_size = 256;
>  
> -		drm_crtc_enable_color_mgmt(crtc, 0, false, gamma_lut_size);
> +		drm_crtc_enable_color_mgmt(crtc, 0, true, gamma_lut_size);
>  		drm_mode_crtc_set_gamma_size(crtc, gamma_lut_size);
>  	}
>  

-- 
Regards,

Laurent Pinchart
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