Re: [PATCH v2 3/4] drm: lcdif: Switch to limited range for RGB to YUV conversion
On Wed, 2022-09-28 at 03:58 +0300, Laurent Pinchart wrote:
> Up to and including v1.3, HDMI supported limited quantization range only
> for YCbCr. HDMI v1.4 introduced selectable quantization ranges, but this
> features isn't supported in the dw-hdmi driver that is used in
s/features/feature/
> conjunction with the LCDIF in the i.MX8MP. The HDMI YCbCr output is thus
> always advertised in the AVI infoframe as limited range.
>
> The LCDIF driver, on the other hand, configures the CSC to produce full
> range YCbCr. This mismatch results in loss of details and incorrect
> colours. Fix it by switching to limited range YCbCr.
>
> The coefficients are copied from drivers/media/platforms/nxp/imx-pxp.c
> for coherency, as the hardware is most likely identical.
>
> Fixes: 9db35bb349a0 ("drm: lcdif: Add support for i.MX8MP LCDIF variant")
> Signed-off-by: Laurent Pinchart
> ---
> Changes since v1:
>
> - Use coefficients from imx-pxp.c
> ---
> drivers/gpu/drm/mxsfb/lcdif_kms.c | 12 ++--
> 1 file changed, 6 insertions(+), 6 deletions(-)
With the typo in commit message fixed:
Reviewed-by: Liu Ying
Re: [PATCH v2 3/4] drm: lcdif: Switch to limited range for RGB to YUV conversion
Quoting Laurent Pinchart (2022-09-28 01:58:11)
> Up to and including v1.3, HDMI supported limited quantization range only
> for YCbCr. HDMI v1.4 introduced selectable quantization ranges, but this
> features isn't supported in the dw-hdmi driver that is used in
> conjunction with the LCDIF in the i.MX8MP. The HDMI YCbCr output is thus
> always advertised in the AVI infoframe as limited range.
>
> The LCDIF driver, on the other hand, configures the CSC to produce full
> range YCbCr. This mismatch results in loss of details and incorrect
> colours. Fix it by switching to limited range YCbCr.
>
> The coefficients are copied from drivers/media/platforms/nxp/imx-pxp.c
> for coherency, as the hardware is most likely identical.
Perhaps we need one or two of these somewhere:
https://colorconfidence.com/products/calibrite-colorchecker-display
Or does anyone have one that could test this patch?
Anyway:
Reviewed-by: Kieran Bingham
> Fixes: 9db35bb349a0 ("drm: lcdif: Add support for i.MX8MP LCDIF variant")
> Signed-off-by: Laurent Pinchart
> ---
> Changes since v1:
>
> - Use coefficients from imx-pxp.c
> ---
> drivers/gpu/drm/mxsfb/lcdif_kms.c | 12 ++--
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/mxsfb/lcdif_kms.c
> b/drivers/gpu/drm/mxsfb/lcdif_kms.c
> index 1f22ea5896d5..c3622be0c587 100644
> --- a/drivers/gpu/drm/mxsfb/lcdif_kms.c
> +++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c
> @@ -53,16 +53,16 @@ static void lcdif_set_formats(struct lcdif_drm_private
> *lcdif,
> writel(DISP_PARA_LINE_PATTERN_UYVY_H,
>lcdif->base + LCDC_V8_DISP_PARA);
>
> - /* CSC: BT.601 Full Range RGB to YCbCr coefficients. */
> - writel(CSC0_COEF0_A2(0x096) | CSC0_COEF0_A1(0x04c),
> + /* CSC: BT.601 Limited Range RGB to YCbCr coefficients. */
> + writel(CSC0_COEF0_A2(0x081) | CSC0_COEF0_A1(0x041),
>lcdif->base + LCDC_V8_CSC0_COEF0);
> - writel(CSC0_COEF1_B1(0x7d5) | CSC0_COEF1_A3(0x01d),
> + writel(CSC0_COEF1_B1(0x7db) | CSC0_COEF1_A3(0x019),
>lcdif->base + LCDC_V8_CSC0_COEF1);
> - writel(CSC0_COEF2_B3(0x080) | CSC0_COEF2_B2(0x7ac),
> + writel(CSC0_COEF2_B3(0x070) | CSC0_COEF2_B2(0x7b6),
>lcdif->base + LCDC_V8_CSC0_COEF2);
> - writel(CSC0_COEF3_C2(0x795) | CSC0_COEF3_C1(0x080),
> + writel(CSC0_COEF3_C2(0x7a2) | CSC0_COEF3_C1(0x070),
>lcdif->base + LCDC_V8_CSC0_COEF3);
> - writel(CSC0_COEF4_D1(0x000) | CSC0_COEF4_C3(0x7ec),
> + writel(CSC0_COEF4_D1(0x010) | CSC0_COEF4_C3(0x7ee),
>lcdif->base + LCDC_V8_CSC0_COEF4);
> writel(CSC0_COEF5_D3(0x080) | CSC0_COEF5_D2(0x080),
>lcdif->base + LCDC_V8_CSC0_COEF5);
> --
> Regards,
>
> Laurent Pinchart
>
Re: [PATCH v2 3/4] drm: lcdif: Switch to limited range for RGB to YUV conversion
On 9/28/22 02:58, Laurent Pinchart wrote:
Up to and including v1.3, HDMI supported limited quantization range only
for YCbCr. HDMI v1.4 introduced selectable quantization ranges, but this
features isn't supported in the dw-hdmi driver that is used in
conjunction with the LCDIF in the i.MX8MP. The HDMI YCbCr output is thus
always advertised in the AVI infoframe as limited range.
The LCDIF driver, on the other hand, configures the CSC to produce full
range YCbCr. This mismatch results in loss of details and incorrect
colours. Fix it by switching to limited range YCbCr.
The coefficients are copied from drivers/media/platforms/nxp/imx-pxp.c
for coherency, as the hardware is most likely identical.
Fixes: 9db35bb349a0 ("drm: lcdif: Add support for i.MX8MP LCDIF variant")
Signed-off-by: Laurent Pinchart
Reviewed-by: Marek Vasut
[PATCH v2 3/4] drm: lcdif: Switch to limited range for RGB to YUV conversion
Up to and including v1.3, HDMI supported limited quantization range only
for YCbCr. HDMI v1.4 introduced selectable quantization ranges, but this
features isn't supported in the dw-hdmi driver that is used in
conjunction with the LCDIF in the i.MX8MP. The HDMI YCbCr output is thus
always advertised in the AVI infoframe as limited range.
The LCDIF driver, on the other hand, configures the CSC to produce full
range YCbCr. This mismatch results in loss of details and incorrect
colours. Fix it by switching to limited range YCbCr.
The coefficients are copied from drivers/media/platforms/nxp/imx-pxp.c
for coherency, as the hardware is most likely identical.
Fixes: 9db35bb349a0 ("drm: lcdif: Add support for i.MX8MP LCDIF variant")
Signed-off-by: Laurent Pinchart
---
Changes since v1:
- Use coefficients from imx-pxp.c
---
drivers/gpu/drm/mxsfb/lcdif_kms.c | 12 ++--
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/mxsfb/lcdif_kms.c
b/drivers/gpu/drm/mxsfb/lcdif_kms.c
index 1f22ea5896d5..c3622be0c587 100644
--- a/drivers/gpu/drm/mxsfb/lcdif_kms.c
+++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c
@@ -53,16 +53,16 @@ static void lcdif_set_formats(struct lcdif_drm_private
*lcdif,
writel(DISP_PARA_LINE_PATTERN_UYVY_H,
lcdif->base + LCDC_V8_DISP_PARA);
- /* CSC: BT.601 Full Range RGB to YCbCr coefficients. */
- writel(CSC0_COEF0_A2(0x096) | CSC0_COEF0_A1(0x04c),
+ /* CSC: BT.601 Limited Range RGB to YCbCr coefficients. */
+ writel(CSC0_COEF0_A2(0x081) | CSC0_COEF0_A1(0x041),
lcdif->base + LCDC_V8_CSC0_COEF0);
- writel(CSC0_COEF1_B1(0x7d5) | CSC0_COEF1_A3(0x01d),
+ writel(CSC0_COEF1_B1(0x7db) | CSC0_COEF1_A3(0x019),
lcdif->base + LCDC_V8_CSC0_COEF1);
- writel(CSC0_COEF2_B3(0x080) | CSC0_COEF2_B2(0x7ac),
+ writel(CSC0_COEF2_B3(0x070) | CSC0_COEF2_B2(0x7b6),
lcdif->base + LCDC_V8_CSC0_COEF2);
- writel(CSC0_COEF3_C2(0x795) | CSC0_COEF3_C1(0x080),
+ writel(CSC0_COEF3_C2(0x7a2) | CSC0_COEF3_C1(0x070),
lcdif->base + LCDC_V8_CSC0_COEF3);
- writel(CSC0_COEF4_D1(0x000) | CSC0_COEF4_C3(0x7ec),
+ writel(CSC0_COEF4_D1(0x010) | CSC0_COEF4_C3(0x7ee),
lcdif->base + LCDC_V8_CSC0_COEF4);
writel(CSC0_COEF5_D3(0x080) | CSC0_COEF5_D2(0x080),
lcdif->base + LCDC_V8_CSC0_COEF5);
--
Regards,
Laurent Pinchart
