On 9/28/22 03:54, Laurent Pinchart wrote:
Hi Marek,
Hi,
+ /*
+ * The CSC differentiates between "YCbCr" and "YUV", but the reference
+ * manual doesn't detail how they differ. Experiments showed that the
+ * luminance value is unaffected, only the calculations involving chroma
+ * values differ. The YCbCr mode behaves as expected, with chroma values
+ * being offset by 128. The YUV mode isn't fully understood.
+ */
+ if (!in_yuv && out_yuv) {
+ /* RGB -> YCbCr */
+ writel(CSC0_CTRL_CSC_MODE_RGB2YCbCr,
+ lcdif->base + LCDC_V8_CSC0_CTRL);
+
+ /* 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(0x7db) | CSC0_COEF1_A3(0x019),
+ lcdif->base + LCDC_V8_CSC0_COEF1);
+ writel(CSC0_COEF2_B3(0x070) | CSC0_COEF2_B2(0x7b6),
+ lcdif->base + LCDC_V8_CSC0_COEF2);
+ writel(CSC0_COEF3_C2(0x7a2) | CSC0_COEF3_C1(0x070),
+ lcdif->base + LCDC_V8_CSC0_COEF3);
+ 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);
Would it make sense to turn the above ^ into a nice coeffs table like
the lcdif_yuv2rgb_coeffs table used in the else if branch below ?
I thought about that, and decided to leave it as-is given that only one
encoding and quantization range is supported. It could be nice to fix
this, but it would then involve work in the dw-hdmi driver to select the
quantization through the AVI infoframe, as well as more work here to
pick a default based on the device capabilites reported through EDID.
I've decided not to explore that rabbit hole :-)
This being said, the coefficients could be moved to a table already even
without support for multiple encodings or ranges. Feel free to add a
patch on top, I'll review it :-)
I'll just add it to the end of my todo list ...
+ } else if (in_yuv && !out_yuv) {
+ /* YCbCr -> RGB */
+ const u32 *coeffs =
+ lcdif_yuv2rgb_coeffs[plane_state->color_encoding]
+ [plane_state->color_range];
+
+ writel(CSC0_CTRL_CSC_MODE_YCbCr2RGB,
+ lcdif->base + LCDC_V8_CSC0_CTRL);
+
+ writel(coeffs[0], lcdif->base + LCDC_V8_CSC0_COEF0);
+ writel(coeffs[1], lcdif->base + LCDC_V8_CSC0_COEF1);
+ writel(coeffs[2], lcdif->base + LCDC_V8_CSC0_COEF2);
+ writel(coeffs[3], lcdif->base + LCDC_V8_CSC0_COEF3);
+ writel(coeffs[4], lcdif->base + LCDC_V8_CSC0_COEF4);
+ writel(coeffs[5], lcdif->base + LCDC_V8_CSC0_COEF5);
+ } else {
+ /* RGB -> RGB, YCbCr -> YCbCr: bypass colorspace converter. */
+ writel(CSC0_CTRL_BYPASS, lcdif->base + LCDC_V8_CSC0_CTRL);
+ }
}
static void lcdif_set_mode(struct lcdif_drm_private *lcdif, u32 bus_flags)
[...]
@@ -469,6 +593,11 @@ static const u64 lcdif_modifiers[] = {
int lcdif_kms_init(struct lcdif_drm_private *lcdif)
{
+ const u32 supported_encodings = BIT(DRM_COLOR_YCBCR_BT601)
+ | BIT(DRM_COLOR_YCBCR_BT709)
+ | BIT(DRM_COLOR_YCBCR_BT2020);
+ const u32 supported_ranges = BIT(DRM_COLOR_YCBCR_LIMITED_RANGE)
+ | BIT(DRM_COLOR_YCBCR_FULL_RANGE);
Nitpick, is the | operator in front OK, or should it be at the end of
the line ?
I'll move it to the end of the line.
Thanks. Let's wait a bit for the other reviews and then let's apply this
all.
