Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
Cc: Clint Taylor <clinton.a.taylor@xxxxxxxxx>
Cc: Adam Jackson <ajax@xxxxxxxxxx>
Cc: Harry Wentland <harry.wentland@xxxxxxx>
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
---
drivers/gpu/drm/drm_dp_helper.c | 52 +++++++++++++++++++++++++++++++++++++++--
include/drm/drm_dp_helper.h | 32 +++++++++++++++++++++++++
2 files changed, 82 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 52e0ca9a5bb1..213fb837e1c4 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -1209,6 +1209,51 @@ int drm_dp_stop_crc(struct drm_dp_aux *aux)
}
EXPORT_SYMBOL(drm_dp_stop_crc);
+struct dpcd_quirk {
+ u8 oui[3];
+ bool is_branch;
+ u32 quirks;
+};
+
+#define OUI(first, second, third) { (first), (second), (third) }
+
+static const struct dpcd_quirk dpcd_quirk_list[] = {
+ /* Analogix 7737 needs reduced M and N at HBR2 link rates */
+ { OUI(0x00, 0x22, 0xb9), true, BIT(DP_DPCD_QUIRK_LIMITED_M_N) },
+};
+
+#undef OUI
+
+/*
+ * Get a bit mask of DPCD quirks for the sink/branch device identified by
+ * ident. The quirk data is shared but it's up to the drivers to act on the
+ * data.
+ *
+ * For now, only the OUI (first three bytes) is used, but this may be extended
+ * to device identification string and hardware/firmware revisions later.
+ */
+static u32
+drm_dp_get_quirks(const struct drm_dp_dpcd_ident *ident, bool is_branch)
+{
+ const struct dpcd_quirk *quirk;
+ u32 quirks = 0;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(dpcd_quirk_list); i++) {
+ quirk = &dpcd_quirk_list[i];
+
+ if (quirk->is_branch != is_branch)
+ continue;
+
+ if (memcmp(quirk->oui, ident->oui, sizeof(ident->oui)) != 0)
+ continue;
+
+ quirks |= quirk->quirks;
+ }
+
+ return quirks;
+}
+
/**
* drm_dp_read_desc - read sink/branch descriptor from DPCD
* @aux: DisplayPort AUX channel
@@ -1231,14 +1276,17 @@ int drm_dp_read_desc(struct drm_dp_aux *aux, struct drm_dp_desc *desc,
if (ret < 0)
return ret;
+ desc->quirks = drm_dp_get_quirks(ident, is_branch);
+
dev_id_len = strnlen(ident->device_id, sizeof(ident->device_id));
- DRM_DEBUG_KMS("DP %s: OUI %*phD dev-ID %*pE HW-rev %d.%d SW-rev %d.%d\n",
+ DRM_DEBUG_KMS("DP %s: OUI %*phD dev-ID %*pE HW-rev %d.%d SW-rev %d.%d quirks 0x%04x\n",
is_branch ? "branch" : "sink",
(int)sizeof(ident->oui), ident->oui,
dev_id_len, ident->device_id,
ident->hw_rev >> 4, ident->hw_rev & 0xf,
- ident->sw_major_rev, ident->sw_minor_rev);
+ ident->sw_major_rev, ident->sw_minor_rev,
+ desc->quirks);
return 0;
}
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index aee5b96b51d7..717cb8496725 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1090,12 +1090,44 @@ struct drm_dp_dpcd_ident {
/**
* struct drm_dp_desc - DP branch/sink device descriptor
* @ident: DP device identification from DPCD 0x400 (sink) or 0x500 (branch).
+ * @quirks: Quirks; use drm_dp_has_quirk() to query for the quirks.
*/
struct drm_dp_desc {
struct drm_dp_dpcd_ident ident;
+ u32 quirks;
};
int drm_dp_read_desc(struct drm_dp_aux *aux, struct drm_dp_desc *desc,
bool is_branch);
+/**
+ * enum drm_dp_quirk - Display Port sink/branch device specific quirks
+ *
+ * Display Port sink and branch devices in the wild have a variety of bugs, try
+ * to collect them here. The quirks are shared, but it's up to the drivers to
+ * implement workarounds for them.
+ */
+enum drm_dp_quirk {
+ /**
+ * @DP_DPCD_QUIRK_LIMITED_M_N:
+ *
+ * The device requires main link attributes Mdiv and Ndiv to be limited
+ * to 16 bits.
+ */
+ DP_DPCD_QUIRK_LIMITED_M_N,
+};
+
+/**
+ * drm_dp_has_quirk() - does the DP device have a specific quirk
+ * @desc: Device decriptor filled by drm_dp_read_desc()
+ * @quirk: Quirk to query for
+ *
+ * Return true if DP device identified by @desc has @quirk.
+ */
+static inline bool
+drm_dp_has_quirk(const struct drm_dp_desc *desc, enum drm_dp_quirk quirk)
+{
+ return desc->quirks & BIT(quirk);
+}
+
#endif /* _DRM_DP_HELPER_H_ */
