[PATCH 04/12] drm/dp: Probe link using existing parsing helpers

[Thierry Reding]

From: Thierry Reding <tred...@nvidia.com>

Use existing parsing helpers to probe a DisplayPort link.

Signed-off-by: Thierry Reding <treding at nvidia.com>
---
 drivers/gpu/drm/drm_dp_helper.c | 29 ++++++++++++++++++++++-------
 include/drm/drm_dp_helper.h     |  2 ++
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index cdc0da67e8ad..54d8398cf3a6 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -269,6 +269,22 @@ ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned 
int offset,
 EXPORT_SYMBOL(drm_dp_dpcd_write);

 /**
+ * drm_dp_dpcd_read_link_caps() - read DPCD link capabilities
+ * @aux: DisplayPort AUX channel
+ * @caps: buffer to store the link capabilities in
+ *
+ * Returns:
+ * The number of bytes transferred on success or a negative error code on
+ * failure.
+ */
+int drm_dp_dpcd_read_link_caps(struct drm_dp_aux *aux,
+                              u8 caps[DP_RECEIVER_CAP_SIZE])
+{
+       return drm_dp_dpcd_read(aux, DP_DPCD_REV, caps, DP_RECEIVER_CAP_SIZE);
+}
+EXPORT_SYMBOL(drm_dp_dpcd_read_link_caps);
+
+/**
  * 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)
@@ -323,21 +339,20 @@ static void drm_dp_link_reset(struct drm_dp_link *link)
  */
 int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link)
 {
-       u8 values[3];
+       u8 values[DP_RECEIVER_CAP_SIZE];
        int err;

        drm_dp_link_reset(link);

-       err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values));
+       err = drm_dp_dpcd_read_link_caps(aux, values);
        if (err < 0)
                return err;

-       link->revision = values[0];
-       link->max_rate = drm_dp_bw_code_to_link_rate(values[1]);
-       link->max_lanes = values[2] & DP_MAX_LANE_COUNT_MASK;
+       link->revision = values[DP_DPCD_REV];
+       link->max_rate = drm_dp_max_link_rate(values);
+       link->max_lanes = drm_dp_max_lane_count(values);

-       if (values[2] & DP_ENHANCED_FRAME_CAP)
-               link->caps.enhanced_framing = true;
+       link->caps.enhanced_framing = drm_dp_enhanced_frame_cap(values);

        link->rate = link->max_rate;
        link->lanes = link->max_lanes;
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 20e4fe2e13c5..4929b3ea30e3 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -747,6 +747,8 @@ 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_caps(struct drm_dp_aux *aux,
+                              u8 caps[DP_RECEIVER_CAP_SIZE]);
 int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
                                 u8 status[DP_LINK_STATUS_SIZE]);

-- 
2.5.0