[PATCH v2 16/28] drm/i2c: tda998x: change the video quantization

[Jean-Francois Moine]

This patch changes the video quantization to RGB/YUV.

Signed-off-by: Jean-Francois Moine <moi...@free.fr>
---
drivers/gpu/drm/i2c/tda998x_drv.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c
index 91bd4e8..f60aef9 100644
--- a/drivers/gpu/drm/i2c/tda998x_drv.c
+++ b/drivers/gpu/drm/i2c/tda998x_drv.c
@@ -992,7 +992,9 @@ tda998x_encoder_mode_set(struct drm_encoder *encoder,
reg_clear(priv, REG_PLL_SERIAL_1, PLL_SERIAL_1_SRL_MAN_IZ);
reg_clear(priv, REG_PLL_SERIAL_3, PLL_SERIAL_3_SRL_DE);
reg_write(priv, REG_SERIALIZER, 0);
- reg_write(priv, REG_HVF_CNTRL_1, HVF_CNTRL_1_VQR(0));
+
+ /* video quantization range = 0: full, 1: RGB/YUV, 2: YUV */
+ reg_write(priv, REG_HVF_CNTRL_1, HVF_CNTRL_1_VQR(1));

/* TODO enable pixel repeat for pixel rates less than 25Msamp/s */
rep = 0;
--
Ken ar c'hentañ | ** Breizh ha Linux atav! **
Jef | http://moinejf.free.fr/
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[Russell King - ARM Linux]

On Thu, Jan 09, 2014 at 12:05:00PM +0100, Jean-Francois Moine wrote:
> This patch changes the video quantization to RGB/YUV.

Strong NAK, this patch is definitely incorrect.

The Cubox (which I assume is the platform you're generating these patches
for) produces RGB at it's output, which are the RGB values from the
framebuffer. Being a computer-like "IT" source, these RGB values have the
full range, from zero to 255, rather than the limited range of 16 to 235.

With limited range, a value of 16 is black and 235 is white. However, the
values in the framebuffer will be zero for black and 255 for white.

A VQR value of 1 gives limited range of 16 to 235, whereas zero gives
full range. The value of zero is correct here.

--
FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up. Estimation
in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad.
Estimate before purchase was "up to 13.2Mbit".