HW revision is mandatory field for DisplayPort branch
devices. This is defined in DPCD register field 0x509.
Signed-off-by: Mika Kahola <mika.kahola@xxxxxxxxx>
---
drivers/gpu/drm/drm_dp_helper.c | 21 +++++++++++++++++++++
include/drm/drm_dp_helper.h | 7 +++++++
2 files changed, 28 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 0c83685..b5ae189 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -514,6 +514,27 @@ int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
EXPORT_SYMBOL(drm_dp_downstream_max_bpc);
/**
+ * drm_dp_downstream_hw_rev() - read DP branch device HW revision
+ * @aux: DisplayPort AUX channel
+ *
+ * Returns HW revision on succes or negative error code on failure
+ */
+struct drm_dp_revision drm_dp_downstream_hw_rev(struct drm_dp_aux *aux)
+{
+ uint8_t tmp;
+ struct drm_dp_revision rev = { .major = -EINVAL, .minor = -EINVAL };
+
+ if (drm_dp_dpcd_read(aux, DP_BRANCH_HW_REV, &tmp, 1) != 1)
+ return rev;
+
+ rev.major = (tmp & 0xf0) >> 4;
+ rev.minor = tmp & 0xf;
+
+ return rev;
+}
+EXPORT_SYMBOL(drm_dp_downstream_hw_rev);
+
+/**
* drm_dp_downstream_id() - identify branch device
* @aux: DisplayPort AUX channel
*
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 88bf3bf..641bf3d 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -446,6 +446,7 @@
#define DP_SINK_OUI 0x400
#define DP_BRANCH_OUI 0x500
#define DP_BRANCH_ID 0x503
+#define DP_BRANCH_HW_REV 0x509
#define DP_SET_POWER 0x600
# define DP_SET_POWER_D0 0x1
@@ -803,6 +804,11 @@ struct drm_dp_link {
unsigned long capabilities;
};
+struct drm_dp_revision {
+ int major;
+ int minor;
+};
+
int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link);
int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link);
int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link);
@@ -812,6 +818,7 @@ int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4]);
int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6]);
+struct drm_dp_revision drm_dp_downstream_hw_rev(struct drm_dp_aux *aux);
int drm_dp_aux_register(struct drm_dp_aux *aux);
void drm_dp_aux_unregister(struct drm_dp_aux *aux);
--
1.9.1
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