[PATCH] drm/meson: Fix OSD1 RGB to YCbCr coefficient

[PATCH] drm/meson: Fix OSD1 RGB to YCbCr coefficient

[Stuart Menefy]

VPP_WRAP_OSD1_MATRIX_COEF22.Coeff22 is documented as being bits 0-12,
not 16-28.

Without this the output tends to have a pink hue, changing it results
in better color accuracy.

The vendor kernel doesn't use this register. However the code which
sets VIU2_OSD1_MATRIX_COEF22 also uses bits 0-12. There is a slightly
different style of registers for configuring some of the other matrices,
which do use bits 16-28 for this coefficient, but those have names
ending in MATRIX_COEF22_30, and this is not one of those.

Signed-off-by: Stuart Menefy <stuart.menefy@mathembedded.com>
---
 drivers/gpu/drm/meson/meson_viu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/meson/meson_viu.c b/drivers/gpu/drm/meson/meson_viu.c
index 51df4de..876ffe0 100644
--- a/drivers/gpu/drm/meson/meson_viu.c
+++ b/drivers/gpu/drm/meson/meson_viu.c
@@ -94,7 +94,7 @@ static void meson_viu_set_g12a_osd1_matrix(struct meson_drm *priv,
 		priv->io_base + _REG(VPP_WRAP_OSD1_MATRIX_COEF11_12));
 	writel(((m[9] & 0x1fff) << 16) | (m[10] & 0x1fff),
 		priv->io_base + _REG(VPP_WRAP_OSD1_MATRIX_COEF20_21));
-	writel((m[11] & 0x1fff) << 16,
+	writel((m[11] & 0x1fff),
 		priv->io_base +	_REG(VPP_WRAP_OSD1_MATRIX_COEF22));
 
 	writel(((m[18] & 0xfff) << 16) | (m[19] & 0xfff),
-- 
2.7.4

Re: [PATCH] drm/meson: Fix OSD1 RGB to YCbCr coefficient

[Neil Armstrong]

Hi !

On 08/09/2022 17:52, Stuart Menefy wrote:
> VPP_WRAP_OSD1_MATRIX_COEF22.Coeff22 is documented as being bits 0-12,
> not 16-28.

Thanks, Good catch !

> 
> Without this the output tends to have a pink hue, changing it results
> in better color accuracy.

Indeed, it was a regular issue reported.

> 
> The vendor kernel doesn't use this register. However the code which
> sets VIU2_OSD1_MATRIX_COEF22 also uses bits 0-12. There is a slightly
> different style of registers for configuring some of the other matrices,
> which do use bits 16-28 for this coefficient, but those have names
> ending in MATRIX_COEF22_30, and this is not one of those.
> 

Fixes: 728883948b0d ("drm/meson: Add G12A Support for VIU setup")
> Signed-off-by: Stuart Menefy <stuart.menefy@mathembedded.com>
> ---
>   drivers/gpu/drm/meson/meson_viu.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/meson/meson_viu.c b/drivers/gpu/drm/meson/meson_viu.c
> index 51df4de..876ffe0 100644
> --- a/drivers/gpu/drm/meson/meson_viu.c
> +++ b/drivers/gpu/drm/meson/meson_viu.c
> @@ -94,7 +94,7 @@ static void meson_viu_set_g12a_osd1_matrix(struct meson_drm *priv,
>   		priv->io_base + _REG(VPP_WRAP_OSD1_MATRIX_COEF11_12));
>   	writel(((m[9] & 0x1fff) << 16) | (m[10] & 0x1fff),
>   		priv->io_base + _REG(VPP_WRAP_OSD1_MATRIX_COEF20_21));
> -	writel((m[11] & 0x1fff) << 16,
> +	writel((m[11] & 0x1fff),
>   		priv->io_base +	_REG(VPP_WRAP_OSD1_MATRIX_COEF22));
>   
>   	writel(((m[18] & 0xfff) << 16) | (m[19] & 0xfff),

Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>

Re: [PATCH] drm/meson: Fix OSD1 RGB to YCbCr coefficient

[Neil Armstrong]

Hi,

On Thu, 8 Sep 2022 16:52:43 +0100, Stuart Menefy wrote:
> VPP_WRAP_OSD1_MATRIX_COEF22.Coeff22 is documented as being bits 0-12,
> not 16-28.
> 
> Without this the output tends to have a pink hue, changing it results
> in better color accuracy.
> 
> The vendor kernel doesn't use this register. However the code which
> sets VIU2_OSD1_MATRIX_COEF22 also uses bits 0-12. There is a slightly
> different style of registers for configuring some of the other matrices,
> which do use bits 16-28 for this coefficient, but those have names
> ending in MATRIX_COEF22_30, and this is not one of those.
> 
> [...]

Thanks, Applied to https://anongit.freedesktop.org/git/drm/drm-misc.git (drm-misc-fixes)

[1/1] drm/meson: Fix OSD1 RGB to YCbCr coefficient
      https://cgit.freedesktop.org/drm/drm-misc/commit/?id=6463d3930ba5b6addcfc8f80a4543976a2fc7656

-- 
Neil