All of the SoCs that don't have dithering control in the gamma IP
have got a GAMMA_LUT_TYPE bit that tells to the IP if the LUT is
"descending" (bit set) or "rising" (bit cleared): make sure to set
it correctly after programming the LUT.
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
---
drivers/gpu/drm/mediatek/mtk_disp_gamma.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
index 450da7062db4..b2fe63678cef 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
@@ -23,6 +23,7 @@
#define GAMMA_RELAY_MODE BIT(0)
#define GAMMA_LUT_EN BIT(1)
#define GAMMA_DITHERING BIT(2)
+#define GAMMA_LUT_TYPE BIT(2)
#define DISP_GAMMA_SIZE 0x0030
#define DISP_GAMMA_SIZE_HSIZE GENMASK(28, 16)
#define DISP_GAMMA_SIZE_VSIZE GENMASK(12, 0)
@@ -89,6 +90,16 @@ unsigned int mtk_gamma_get_lut_size(struct device *dev)
return lut_size;
}
+static bool mtk_gamma_lut_is_descending(struct drm_color_lut *lut, u32 lut_size)
+{
+ u64 first, last;
+
+ first = lut[0].red + lut[0].green + lut[0].blue;
+ last = lut[lut_size].red + lut[lut_size].green + lut[lut_size].blue;
+
+ return !!(first > last);
+}
+
void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct drm_crtc_state *state)
{
struct mtk_disp_gamma *gamma = dev_get_drvdata(dev);
@@ -182,6 +193,14 @@ void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct drm_crt
}
}
+ if (gamma && !gamma->data->has_dither) {
+ /* Descending or Rising LUT */
+ if (mtk_gamma_lut_is_descending(lut, lut_size))
+ cfg_val |= FIELD_PREP(GAMMA_LUT_TYPE, 1);
+ else
+ cfg_val &= ~GAMMA_LUT_TYPE;
+ }
+
/* Enable the gamma table */
cfg_val |= FIELD_PREP(GAMMA_LUT_EN, 1);
--
2.40.1
