drm/edid: detect SCDC support in HF-VSDB
This patch does following:
- Adds a new structure (drm_hdmi_info) in drm_display_info.
This structure will be used to save and indicate if sink
supports advanced HDMI 2.0 features
- Adds another structure drm_scdc within drm_hdmi_info, to
reflect scdc support and capabilities in connected HDMI 2.0 sink.
- Checks the HF-VSDB block for presence of SCDC, and marks it
in scdc structure
- If SCDC is present, checks if sink is capable of generating
SCDC read request, and marks it in scdc structure.
V2: Addressed review comments
Thierry:
- Fix typos in commit message and make abbreviation consistent
across the commit message.
- Change structure object name from hdmi_info -> hdmi
- Fix typos and abbreviations in description of structure drm_hdmi_info
end the description with a full stop.
- Create a structure drm_scdc, and keep all information related to SCDC
register set (supported, read request supported) etc in it.
Ville:
- Change rr -> read_request
- Call drm_detect_scrambling function drm_parse_hf_vsdb so that all
of HF-VSDB parsing can be kept in same function, in incremental
patches.
V3: Rebase.
V4: Rebase.
V5: Rebase.
V6: Addressed review comments from Ville
- Add clock rate calculations for 1/10 and 1/40 ratios
- Remove leftovers from old patchset
V7: Added R-B from Jose.
V8: Rebase.
V9: Rebase.
V10: Rebase.
Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Jose Abreu <joabreu@synopsys.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1489404244-16608-5-git-send-email-shashank.sharma@intel.com
diff --git a/drivers/gpu/drm/drm_scdc_helper.c b/drivers/gpu/drm/drm_scdc_helper.c
index c2dd33f..3cd96a9 100644
--- a/drivers/gpu/drm/drm_scdc_helper.c
+++ b/drivers/gpu/drm/drm_scdc_helper.c
@@ -22,8 +22,10 @@
*/
#include <linux/slab.h>
+#include <linux/delay.h>
#include <drm/drm_scdc_helper.h>
+#include <drm/drmP.h>
/**
* DOC: scdc helpers
@@ -121,3 +123,122 @@ ssize_t drm_scdc_write(struct i2c_adapter *adapter, u8 offset,
return 0;
}
EXPORT_SYMBOL(drm_scdc_write);
+
+/**
+ * drm_scdc_check_scrambling_status - what is status of scrambling?
+ * @adapter: I2C adapter for DDC channel
+ *
+ * Reads the scrambler status over SCDC, and checks the
+ * scrambling status.
+ *
+ * Returns:
+ * True if the scrambling is enabled, false otherwise.
+ */
+
+bool drm_scdc_get_scrambling_status(struct i2c_adapter *adapter)
+{
+ u8 status;
+ int ret;
+
+ ret = drm_scdc_readb(adapter, SCDC_SCRAMBLER_STATUS, &status);
+ if (ret < 0) {
+ DRM_ERROR("Failed to read scrambling status, error %d\n", ret);
+ return false;
+ }
+
+ return status & SCDC_SCRAMBLING_STATUS;
+}
+EXPORT_SYMBOL(drm_scdc_get_scrambling_status);
+
+/**
+ * drm_scdc_set_scrambling - enable scrambling
+ * @adapter: I2C adapter for DDC channel
+ * @enable: bool to indicate if scrambling is to be enabled/disabled
+ *
+ * Writes the TMDS config register over SCDC channel, and:
+ * enables scrambling when enable = 1
+ * disables scrambling when enable = 0
+ *
+ * Returns:
+ * True if scrambling is set/reset successfully, false otherwise.
+ */
+
+bool drm_scdc_set_scrambling(struct i2c_adapter *adapter, bool enable)
+{
+ u8 config;
+ int ret;
+
+ ret = drm_scdc_readb(adapter, SCDC_TMDS_CONFIG, &config);
+ if (ret < 0) {
+ DRM_ERROR("Failed to read tmds config, err=%d\n", ret);
+ return false;
+ }
+
+ if (enable)
+ config |= SCDC_SCRAMBLING_ENABLE;
+ else
+ config &= ~SCDC_SCRAMBLING_ENABLE;
+
+ ret = drm_scdc_writeb(adapter, SCDC_TMDS_CONFIG, config);
+ if (ret < 0) {
+ DRM_ERROR("Failed to enable scrambling, error %d\n", ret);
+ return false;
+ }
+
+ return true;
+}
+EXPORT_SYMBOL(drm_scdc_set_scrambling);
+
+/**
+ * drm_scdc_set_high_tmds_clock_ratio - set TMDS clock ratio
+ * @adapter: I2C adapter for DDC channel
+ * @set: ret or reset the high clock ratio
+ *
+ * TMDS clock ratio calculations go like this:
+ * TMDS character = 10 bit TMDS encoded value
+ * TMDS character rate = The rate at which TMDS characters are transmitted(Mcsc)
+ * TMDS bit rate = 10x TMDS character rate
+ * As per the spec:
+ * TMDS clock rate for pixel clock < 340 MHz = 1x the character rate
+ * = 1/10 pixel clock rate
+ * TMDS clock rate for pixel clock > 340 MHz = 0.25x the character rate
+ * = 1/40 pixel clock rate
+ *
+ * Writes to the TMDS config register over SCDC channel, and:
+ * sets TMDS clock ratio to 1/40 when set = 1
+ * sets TMDS clock ratio to 1/10 when set = 0
+ *
+ * Returns:
+ * True if write is successful, false otherwise.
+ */
+bool drm_scdc_set_high_tmds_clock_ratio(struct i2c_adapter *adapter, bool set)
+{
+ u8 config;
+ int ret;
+
+ ret = drm_scdc_readb(adapter, SCDC_TMDS_CONFIG, &config);
+ if (ret < 0) {
+ DRM_ERROR("Failed to read tmds config, err=%d\n", ret);
+ return false;
+ }
+
+ if (set)
+ config |= SCDC_TMDS_BIT_CLOCK_RATIO_BY_40;
+ else
+ config &= ~SCDC_TMDS_BIT_CLOCK_RATIO_BY_40;
+
+ ret = drm_scdc_writeb(adapter, SCDC_TMDS_CONFIG, config);
+ if (ret < 0) {
+ DRM_ERROR("Failed to set TMDS clock ratio, error %d\n", ret);
+ return false;
+ }
+
+ /*
+ * The spec says that a source should wait minimum 1ms and maximum
+ * 100ms after writing the TMDS config for clock ratio. Lets allow a
+ * wait of upto 2ms here.
+ */
+ usleep_range(1000, 2000);
+ return true;
+}
+EXPORT_SYMBOL(drm_scdc_set_high_tmds_clock_ratio);