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[v4,2/5] drm/dp: Add drm_dp_dpcd_read_link_status()

Message ID 1390332263-11974-3-git-send-email-treding@nvidia.com (mailing list archive)
State New, archived
Headers show

Commit Message

Thierry Reding Jan. 21, 2014, 7:24 p.m. UTC 
The function reads the link status (6 bytes starting at offset 0x202)
from the DPCD so that it can be conveniently passed to other DPCD
helpers.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 drivers/gpu/drm/drm_dp_helper.c | 16 ++++++++++++++++
 include/drm/drm_dp_helper.h     |  3 +++
 2 files changed, 19 insertions(+)
diff mbox

Patch

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 3e74ed93b19f..b26d46b00b05 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -456,3 +456,19 @@  ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
 				  size);
 }
 EXPORT_SYMBOL(drm_dp_dpcd_write);
+
+/**
+ * drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207)
+ * @aux: DisplayPort AUX channel
+ * @status: buffer to store the link status in (must be at least 6 bytes)
+ *
+ * Returns the number of bytes transferred on success or a negative error
+ * code on failure.
+ */
+int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
+				 u8 status[DP_LINK_STATUS_SIZE])
+{
+	return drm_dp_dpcd_read(aux, DP_LANE0_1_STATUS, status,
+				DP_LINK_STATUS_SIZE);
+}
+EXPORT_SYMBOL(drm_dp_dpcd_read_link_status);
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index c69c1dc1b741..8af695277a84 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -465,4 +465,7 @@  static inline ssize_t drm_dp_dpcd_writeb(struct drm_dp_aux *aux,
 	return drm_dp_dpcd_write(aux, offset, &value, 1);
 }
 
+int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
+				 u8 status[DP_LINK_STATUS_SIZE]);
+
 #endif /* _DRM_DP_HELPER_H_ */