Re: [Intel-gfx] [PATCH 4/6] drm: scrambling support in drm layer

[Sharma, Shashank]

Thanks for the review, Dhinakaran.


Regards

Shashank


On 2/2/2017 1:23 AM, Pandiyan, Dhinakaran wrote:

On Wed, 2017-02-01 at 18:14 +0530, Shashank Sharma wrote:

HDMI 2.0 spec mandates scrambling for modes with pixel clock higher
than 340Mhz. This patch adds few new functions in drm layer for
core drivers to enable/disable scrambling.

This patch adds:
- A function to detect scrambling support parsing HF-VSDB
- A function to check scrambling status runtime using SCDC read.
- Two functions to enable/disable scrambling using SCDC read/write.
- Few new bools to reflect scrambling support and status.

Signed-off-by: Shashank Sharma 
---
  drivers/gpu/drm/drm_edid.c  | 131 +++-
  include/drm/drm_connector.h |  24 
  include/drm/drm_edid.h  |   6 +-
  3 files changed, 159 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 37902e5..f0d940a 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -37,6 +37,7 @@
  #include 
  #include 
  #include 
+#include 
  
  #define version_greater(edid, maj, min) \

(((edid)->version > (maj)) || \
@@ -3814,6 +3815,132 @@ static void drm_detect_hdmi_scdc(struct drm_connector 
*connector,
}
  }
  
+static void drm_detect_hdmi_scrambling(struct drm_connector *connector,

+const u8 *hf_vsdb)
+{
+   struct drm_display_info *display = >display_info;
+   struct drm_hdmi_info *hdmi = >hdmi_info;
+
+   /*
+* All HDMI 2.0 monitors must support scrambling at rates > 340M.
+* And as per the spec, three factors confirm this:
+* * Availability of a HF-VSDB block in EDID (check)
+* * Non zero Max_TMDS_Char_Rate filed in HF-VSDB
+* * SCDC support available
+* Lets check it out.
+*/
+
+   if (hf_vsdb[5]) {
+   display->max_tmds_clock = hf_vsdb[5] * 5000;

Comment explaining or quoting where the 5000 comes from?

Sure, can be done.



+   DRM_DEBUG_KMS("HF-VSDB: max TMDS clock %d kHz\n",
+   display->max_tmds_clock);
+
+   if (hdmi->scdc_supported) {
+   hdmi->scr_info.supported = true;
+
+   /* Few sinks support scrambling for cloks < 340M */
+   if ((hf_vsdb[6] & 0x8))
+   hdmi->scr_info.low_clocks = true;
+   }
+   }
+}
+
+/**
+ * drm_check_scrambling_status - what is status of scrambling?
+ * @adapter: i2c adapter for SCDC channel
+ *
+ * Read the scrambler status over SCDC channel, and check the
+ * scrambling status.
+ *
+ * Return: True if the scrambling is enabled, false otherwise.
+ */
+
+bool drm_check_scrambling_status(struct i2c_adapter *adapter)
+{
+   u8 status;
+
+   if (drm_scdc_readb(adapter, SCDC_SCRAMBLER_STATUS, ) < 0) {
+   DRM_ERROR("Failed to read scrambling status\n");
+   return false;
+   }
+
+   status &= SCDC_SCRAMBLING_STATUS;
+   return status != 0;
+}
+
+/**
+ * drm_enable_scrambling - enable scrambling
+ * @connector: target drm_connector
+ * @adapter: i2c adapter for SCDC channel
+ * @force: enable scrambling, even if its already enabled
+ *
+ * Write the TMDS config over SCDC channel, and enable scrambling
+ * Return: True if scrambling is successfully enabled, false otherwise.
+ */
+
+bool drm_enable_scrambling(struct drm_connector *connector,
+   struct i2c_adapter *adapter, bool force)
+{
+   u8 config;
+   struct drm_hdmi_info *hdmi_info = >display_info.hdmi_info;
+
+   if (hdmi_info->scr_info.status && !force) {
+   DRM_DEBUG_KMS("Scrambling already enabled\n");
+   return true;
+   }
+
+   if (drm_scdc_readb(adapter, SCDC_TMDS_CONFIG, ) < 0) {
+   DRM_ERROR("Failed to read tmds config\n");
+   return false;
+   }
+
+   config |= SCDC_SCRAMBLING_ENABLE;
+
+   if (drm_scdc_writeb(adapter, SCDC_TMDS_CONFIG, config) < 0) {
+   DRM_ERROR("Failed to enable scrambling, write error\n");
+   return false;
+   }
+
+   hdmi_info->scr_info.status = drm_check_scrambling_status(adapter);
+   return hdmi_info->scr_info.status;
+}
+
+/**
+ * drm_disable_scrambling - disable scrambling
+ * @connector: target drm_connector
+ * @adapter: i2c adapter for SCDC channel
+ * @force: disable scrambling, even if its already disabled
+ *
+ * Write the TMDS config over SCDC channel, and disable scrambling
+ * Return: True if scrambling is successfully disabled, false otherwise.
+ */
+bool drm_disable_scrambling(struct drm_connector *connector,
+   struct i2c_adapter *adapter, bool force)
+{
+   u8 config;
+   struct drm_hdmi_info *hdmi_info = >display_info.hdmi_info;
+
+   if (!hdmi_info->scr_info.status && 

Re: [Intel-gfx] [PATCH 4/6] drm: scrambling support in drm layer

[Pandiyan, Dhinakaran]

On Wed, 2017-02-01 at 18:14 +0530, Shashank Sharma wrote:
> HDMI 2.0 spec mandates scrambling for modes with pixel clock higher
> than 340Mhz. This patch adds few new functions in drm layer for
> core drivers to enable/disable scrambling.
> 
> This patch adds:
> - A function to detect scrambling support parsing HF-VSDB
> - A function to check scrambling status runtime using SCDC read.
> - Two functions to enable/disable scrambling using SCDC read/write.
> - Few new bools to reflect scrambling support and status.
> 
> Signed-off-by: Shashank Sharma 
> ---
>  drivers/gpu/drm/drm_edid.c  | 131 
> +++-
>  include/drm/drm_connector.h |  24 
>  include/drm/drm_edid.h  |   6 +-
>  3 files changed, 159 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 37902e5..f0d940a 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -37,6 +37,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
>  
>  #define version_greater(edid, maj, min) \
>   (((edid)->version > (maj)) || \
> @@ -3814,6 +3815,132 @@ static void drm_detect_hdmi_scdc(struct drm_connector 
> *connector,
>   }
>  }
>  
> +static void drm_detect_hdmi_scrambling(struct drm_connector *connector,
> +  const u8 *hf_vsdb)
> +{
> + struct drm_display_info *display = >display_info;
> + struct drm_hdmi_info *hdmi = >hdmi_info;
> +
> + /*
> +  * All HDMI 2.0 monitors must support scrambling at rates > 340M.
> +  * And as per the spec, three factors confirm this:
> +  * * Availability of a HF-VSDB block in EDID (check)
> +  * * Non zero Max_TMDS_Char_Rate filed in HF-VSDB
> +  * * SCDC support available
> +  * Lets check it out.
> +  */
> +
> + if (hf_vsdb[5]) {
> + display->max_tmds_clock = hf_vsdb[5] * 5000;

Comment explaining or quoting where the 5000 comes from?

> + DRM_DEBUG_KMS("HF-VSDB: max TMDS clock %d kHz\n",
> + display->max_tmds_clock);
> +
> + if (hdmi->scdc_supported) {
> + hdmi->scr_info.supported = true;
> +
> + /* Few sinks support scrambling for cloks < 340M */
> + if ((hf_vsdb[6] & 0x8))
> + hdmi->scr_info.low_clocks = true;
> + }
> + }
> +}
> +
> +/**
> + * drm_check_scrambling_status - what is status of scrambling?
> + * @adapter: i2c adapter for SCDC channel
> + *
> + * Read the scrambler status over SCDC channel, and check the
> + * scrambling status.
> + *
> + * Return: True if the scrambling is enabled, false otherwise.
> + */
> +
> +bool drm_check_scrambling_status(struct i2c_adapter *adapter)
> +{
> + u8 status;
> +
> + if (drm_scdc_readb(adapter, SCDC_SCRAMBLER_STATUS, ) < 0) {
> + DRM_ERROR("Failed to read scrambling status\n");
> + return false;
> + }
> +
> + status &= SCDC_SCRAMBLING_STATUS;
> + return status != 0;
> +}
> +
> +/**
> + * drm_enable_scrambling - enable scrambling
> + * @connector: target drm_connector
> + * @adapter: i2c adapter for SCDC channel
> + * @force: enable scrambling, even if its already enabled
> + *
> + * Write the TMDS config over SCDC channel, and enable scrambling
> + * Return: True if scrambling is successfully enabled, false otherwise.
> + */
> +
> +bool drm_enable_scrambling(struct drm_connector *connector,
> + struct i2c_adapter *adapter, bool force)
> +{
> + u8 config;
> + struct drm_hdmi_info *hdmi_info = >display_info.hdmi_info;
> +
> + if (hdmi_info->scr_info.status && !force) {
> + DRM_DEBUG_KMS("Scrambling already enabled\n");
> + return true;
> + }
> +
> + if (drm_scdc_readb(adapter, SCDC_TMDS_CONFIG, ) < 0) {
> + DRM_ERROR("Failed to read tmds config\n");
> + return false;
> + }
> +
> + config |= SCDC_SCRAMBLING_ENABLE;
> +
> + if (drm_scdc_writeb(adapter, SCDC_TMDS_CONFIG, config) < 0) {
> + DRM_ERROR("Failed to enable scrambling, write error\n");
> + return false;
> + }
> +
> + hdmi_info->scr_info.status = drm_check_scrambling_status(adapter);
> + return hdmi_info->scr_info.status;
> +}
> +
> +/**
> + * drm_disable_scrambling - disable scrambling
> + * @connector: target drm_connector
> + * @adapter: i2c adapter for SCDC channel
> + * @force: disable scrambling, even if its already disabled
> + *
> + * Write the TMDS config over SCDC channel, and disable scrambling
> + * Return: True if scrambling is successfully disabled, false otherwise.
> + */
> +bool drm_disable_scrambling(struct drm_connector *connector,
> + struct i2c_adapter *adapter, bool force)
> +{
> + u8 config;
> + struct drm_hdmi_info *hdmi_info = >display_info.hdmi_info;
> +
> + if