Re: [PATCH v4 3/3] OMAPDSS: HDMI: Sysfs support to configure quantization

[K, Mythri P]

Hi Tomi,

On Tue, Feb 14, 2012 at 5:52 PM, Tomi Valkeinen tomi.valkei...@ti.com wrote:
 Hi,


 The color range is something that desktops have to handle also, so
 there's probably ways to handle it in DRM. DisplayPort also has the same
 range setting, so it's not specific to HDMI.

 So I propose to add a kernel API for this in the omap_dss_driver, so
 that the users of omapdss may handle setting the range as they see best.

I see , it is fine i shall make it generic dss API.
 Btw, the displayport spec speaks of VESA and CEA ranges. Does HDMI spec
 only speak about limited/full range?

Yes so is the case with HDMI it is full range for VGA and limited
range for rest.
 I also only now realized that we have full/limited range setting in
 video overlay's ATTRIBUTEs also. And it seems that we currently set it
 always to 0, i.e. limited range. I wonder if this causes color
 degradation in case the HDMI/DP output also sets limited range, and thus
 the color range gets scaled down twice...

yes there is a limited/full range bit in dispc for color conversion,
did a quick check using analyzer it doesn't impact the HDMI color
range, so can confirm there is no degradation.

Thanks and regards,
Mythri.
  Tomi

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Re: [PATCH v4 3/3] OMAPDSS: HDMI: Sysfs support to configure quantization

[Tomi Valkeinen]

On Fri, 2012-03-09 at 16:17 +0530, K, Mythri P wrote:

  I also only now realized that we have full/limited range setting in
  video overlay's ATTRIBUTEs also. And it seems that we currently set it
  always to 0, i.e. limited range. I wonder if this causes color
  degradation in case the HDMI/DP output also sets limited range, and thus
  the color range gets scaled down twice...
 
 yes there is a limited/full range bit in dispc for color conversion,
 did a quick check using analyzer it doesn't impact the HDMI color
 range, so can confirm there is no degradation.

Did you try what happens if you set the range to full in DISPC? Because
it should affect HDMI also, so I don't quite understand how there could
be no degradation if both DISPC and HDMI do the range limiting.

 Tomi



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Re: [PATCH v4 3/3] OMAPDSS: HDMI: Sysfs support to configure quantization

[Tomi Valkeinen]

Hi,

On Wed, 2012-02-08 at 11:54 +0530, mythr...@ti.com wrote:
 From: Mythri P K mythr...@ti.com
 
 Add sysfs support for the user space to configure limited range or full range
 quantization for HDMI.
 
 Signed-off-by: Mythri P K mythr...@ti.com

I'd rather not add another non-standard sysfs entry.

The color range is something that desktops have to handle also, so
there's probably ways to handle it in DRM. DisplayPort also has the same
range setting, so it's not specific to HDMI.

So I propose to add a kernel API for this in the omap_dss_driver, so
that the users of omapdss may handle setting the range as they see best.

Btw, the displayport spec speaks of VESA and CEA ranges. Does HDMI spec
only speak about limited/full range?

I also only now realized that we have full/limited range setting in
video overlay's ATTRIBUTEs also. And it seems that we currently set it
always to 0, i.e. limited range. I wonder if this causes color
degradation in case the HDMI/DP output also sets limited range, and thus
the color range gets scaled down twice... 

 Tomi



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[PATCH v4 3/3] OMAPDSS: HDMI: Sysfs support to configure quantization

[mythripk]

From: Mythri P K mythr...@ti.com

Add sysfs support for the user space to configure limited range or full range
quantization for HDMI.

Signed-off-by: Mythri P K mythr...@ti.com
---
 drivers/video/omap2/dss/dss.h |2 +
 drivers/video/omap2/dss/dss_features.c|1 +
 drivers/video/omap2/dss/hdmi.c|   24 +
 drivers/video/omap2/dss/hdmi_panel.c  |   39 -
 drivers/video/omap2/dss/ti_hdmi.h |6 +++-
 drivers/video/omap2/dss/ti_hdmi_4xxx_ip.c |5 ++-
 6 files changed, 73 insertions(+), 4 deletions(-)

diff --git a/drivers/video/omap2/dss/dss.h b/drivers/video/omap2/dss/dss.h
index d4b3dff..c5f2ee4 100644
--- a/drivers/video/omap2/dss/dss.h
+++ b/drivers/video/omap2/dss/dss.h
@@ -512,6 +512,8 @@ int omapdss_hdmi_display_check_timing(struct 
omap_dss_device *dssdev,
struct omap_video_timings *timings);
 int omapdss_hdmi_read_edid(u8 *buf, int len);
 bool omapdss_hdmi_detect(void);
+enum hdmi_range omapdss_hdmi_get_range(void);
+int omapdss_hdmi_set_range(enum hdmi_range range);
 int hdmi_panel_init(void);
 void hdmi_panel_exit(void);
 
diff --git a/drivers/video/omap2/dss/dss_features.c 
b/drivers/video/omap2/dss/dss_features.c
index 419419a..75add3d 100644
--- a/drivers/video/omap2/dss/dss_features.c
+++ b/drivers/video/omap2/dss/dss_features.c
@@ -479,6 +479,7 @@ static const struct ti_hdmi_ip_ops omap4_hdmi_functions = {
defined(CONFIG_SND_OMAP_SOC_OMAP4_HDMI_MODULE)
.audio_enable   =   ti_hdmi_4xxx_wp_audio_enable,
 #endif
+   .configure_range=   ti_hdmi_4xxx_configure_range,
 
 };
 
diff --git a/drivers/video/omap2/dss/hdmi.c b/drivers/video/omap2/dss/hdmi.c
index 92a6679..37a0416 100644
--- a/drivers/video/omap2/dss/hdmi.c
+++ b/drivers/video/omap2/dss/hdmi.c
@@ -384,6 +384,30 @@ static void hdmi_power_off(struct omap_dss_device *dssdev)
hdmi_runtime_put();
 }
 
+int omapdss_hdmi_set_range(enum hdmi_range range)
+{
+   int r = 0;
+
+   /* HDMI 1.3 section 6.6 VGA (640x480) format requires Full Range */
+   if ((range == HDMI_LIMITED_RANGE) 
+   ((hdmi.ip_data.cfg.cm.code == 4 
+   hdmi.ip_data.cfg.cm.mode == HDMI_DVI) ||
+   (hdmi.ip_data.cfg.cm.code == 1 
+   hdmi.ip_data.cfg.cm.mode == HDMI_HDMI)))
+   return -EINVAL;
+
+   r = hdmi.ip_data.ops-configure_range(hdmi.ip_data, range);
+   if (!r)
+   hdmi.ip_data.range = range;
+
+   return r;
+}
+
+enum hdmi_range omapdss_hdmi_get_range(void)
+{
+   return hdmi.ip_data.range;
+}
+
 int omapdss_hdmi_display_check_timing(struct omap_dss_device *dssdev,
struct omap_video_timings *timings)
 {
diff --git a/drivers/video/omap2/dss/hdmi_panel.c 
b/drivers/video/omap2/dss/hdmi_panel.c
index 533d5dc..81b15de 100644
--- a/drivers/video/omap2/dss/hdmi_panel.c
+++ b/drivers/video/omap2/dss/hdmi_panel.c
@@ -33,6 +33,37 @@ static struct {
struct mutex hdmi_lock;
 } hdmi;
 
+static ssize_t hdmi_range_show(struct device *dev,
+   struct device_attribute *attr, char *buf)
+{
+   enum hdmi_range range;
+
+   range = omapdss_hdmi_get_range();
+   return snprintf(buf, PAGE_SIZE, %d\n, range);
+}
+
+static ssize_t hdmi_range_store(struct device *dev,
+   struct device_attribute *attr,
+   const char *buf, size_t size)
+{
+   enum hdmi_range range;
+   int r ;
+
+   if (strncmp(limited, buf, 7) == 0)
+   range = HDMI_LIMITED_RANGE;
+   else if (strncmp(full, buf, 4) == 0)
+   range = HDMI_FULL_RANGE;
+   else
+   return -EINVAL;
+
+   r = omapdss_hdmi_set_range(range);
+   if (r)
+   return r;
+
+   return size;
+}
+
+static DEVICE_ATTR(range, S_IRUGO | S_IWUSR, hdmi_range_show, 
hdmi_range_store);
 
 static int hdmi_panel_probe(struct omap_dss_device *dssdev)
 {
@@ -41,6 +72,12 @@ static int hdmi_panel_probe(struct omap_dss_device *dssdev)
dssdev-panel.config = OMAP_DSS_LCD_TFT |
OMAP_DSS_LCD_IVS | OMAP_DSS_LCD_IHS;
 
+   /* sysfs entry to provide user space control to set
+* quantization range
+*/
+   if (device_create_file(dssdev-dev, dev_attr_range))
+   DSSERR(failed to create sysfs file\n);
+
dssdev-panel.timings = (struct omap_video_timings){640, 480, 25175, 
96, 16, 48, 2 , 11, 31};
 
DSSDBG(hdmi_panel_probe x_res= %d y_res = %d\n,
@@ -51,7 +88,7 @@ static int hdmi_panel_probe(struct omap_dss_device *dssdev)
 
 static void hdmi_panel_remove(struct omap_dss_device *dssdev)
 {
-
+   device_remove_file(dssdev-dev, dev_attr_range);
 }
 
 static int hdmi_panel_enable(struct omap_dss_device *dssdev)
diff --git a/drivers/video/omap2/dss/ti_hdmi.h 
b/drivers/video/omap2/dss/ti_hdmi.h
index ab0f2c2..a4dcb83 100644
--- a/drivers/video/omap2/dss/ti_hdmi.h