MLK-18809: drm: imx: dcss: revert the max upscale ratio to 1:8

The DCSS RM states that the maximum upscale ratio is 1:8. However, DCSS
HW team suggested some time back that upscale ratios of 1:16 could be
achieved with DCSS scaler, though these ratios were not validated.

Unfortunately there are corner cases, when the upscale ratio nears
1:16, that fail. At the recommendation of DCSS designers, we revert the
maximum ratio to 1:8 until further notice.

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@nxp.com>
(cherry picked from commit bafb5a9481c289951872923d4bbbbcf24a8910b5)

diff --git a/drivers/gpu/imx/dcss/dcss-scaler.c b/drivers/gpu/imx/dcss/dcss-scaler.c
index 2e2a865..1786924 100644 (file)
--- a/drivers/gpu/imx/dcss/dcss-scaler.c
+++ b/drivers/gpu/imx/dcss/dcss-scaler.c
@@ -523,15 +523,15 @@ struct dcss_scaler_ratios {
 };
 
 static const struct dcss_scaler_ratios dcss_scaler_ratios[] = {
-       {max_downscale(3), max_upscale(16)},
-       {max_downscale(5), max_upscale(16)},
-       {max_downscale(5), max_upscale(16)},
+       {max_downscale(3), max_upscale(8)},
+       {max_downscale(5), max_upscale(8)},
+       {max_downscale(5), max_upscale(8)},
 };
 
 static const struct dcss_scaler_ratios dcss_scaler_wrscl_ratios[] = {
-       {max_downscale(5), max_upscale(16)},
-       {max_downscale(7), max_upscale(16)},
-       {max_downscale(7), max_upscale(16)},
+       {max_downscale(5), max_upscale(8)},
+       {max_downscale(7), max_upscale(8)},
+       {max_downscale(7), max_upscale(8)},
 };
 
 static bool dcss_scaler_fractions_set(struct dcss_soc *dcss, int ch_num,