[PATCH 1/1] drm/bridge: analogix_dp: add a quirk for Bob panel

[Kencp huang]

From: zain wang <wzz at rock-chips.com>

Some panels' DP_PSR_STATUS (DPCD 0x2008) may be unstable when we
enable psr. If we get the unexpected psr state, We need try the
debounce to ensure the panel was in PSR

Signed-off-by: zain wang <wzz at rock-chips.com>
Signed-off-by: Chris Zhong <zyw at rock-chips.com>
Commit-Ready: Kristian H. Kristensen <hoegsberg at chromium.org>
Tested-by: Kristian H. Kristensen <hoegsberg at chromium.org>
Reviewed-by: Kristian H. Kristensen <hoegsberg at chromium.org>
Tested-by: Kencp huang <kencp_huang at asus.corp-partner.google.com>
Signed-off-by: Kencp huang <kencp_huang at asus.corp-partner.google.com>
---
 .../gpu/drm/bridge/analogix/analogix_dp_reg.c | 71 +++++++++++--------
 1 file changed, 42 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
index 6a4f20fccf84..7b6e3f8f85b0 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
@@ -935,25 +935,54 @@ void analogix_dp_enable_psr_crc(struct analogix_dp_device *dp)
 	writel(PSR_VID_CRC_ENABLE, dp->reg_base + ANALOGIX_DP_CRC_CON);
 }
 
-static ssize_t analogix_dp_get_psr_status(struct analogix_dp_device *dp)
+static int analogix_dp_get_psr_status(struct analogix_dp_device *dp,
+				      int status)
 {
 	ssize_t val;
-	u8 status;
+	u8 reg, store = 0;
+	int cnt = 0;
+
+	/* About 3ms for a loop */
+	while (cnt < 100) {
+		/* Read operation would takes 900us */
+		val = drm_dp_dpcd_readb(&dp->aux, DP_PSR_STATUS, &reg);
+		if (val < 0) {
+			dev_err(dp->dev, "PSR_STATUS read failed ret=%zd", val);
+			return val;
+		}
+
+		/*
+		 * Ensure the PSR_STATE should go to DP_PSR_SINK_ACTIVE_RFB
+		 * from DP_PSR_SINK_ACTIVE_SINK_SYNCED or
+		 * DP_PSR_SINK_ACTIVE_SRC_SYNCED.
+		 * Otherwise, if we get DP_PSR_SINK_ACTIVE_RFB twice in
+		 * succession, it show the Panel is stable PSR enabled state.
+		 */
+		if (status == DP_PSR_SINK_ACTIVE_RFB) {
+			if ((reg == DP_PSR_SINK_ACTIVE_RFB) &&
+			    ((store == DP_PSR_SINK_ACTIVE_SINK_SYNCED) ||
+			     (store == DP_PSR_SINK_ACTIVE_SRC_SYNCED) ||
+			     (store == DP_PSR_SINK_ACTIVE_RFB)))
+				return 0;
+			else
+				store = reg;
+		} else {
+			if ((reg == DP_PSR_SINK_INACTIVE) ||
+			    (reg == DP_PSR_SINK_ACTIVE_RESYNC))
+				return 0;
+		}
 
-	val = drm_dp_dpcd_readb(&dp->aux, DP_PSR_STATUS, &status);
-	if (val < 0) {
-		dev_err(dp->dev, "PSR_STATUS read failed ret=%zd", val);
-		return val;
+		usleep_range(2100, 2200);
+		cnt++;
 	}
-	return status;
+
+	return -ETIMEDOUT;
 }
 
 int analogix_dp_send_psr_spd(struct analogix_dp_device *dp,
 			     struct dp_sdp *vsc, bool blocking)
 {
 	unsigned int val;
-	int ret;
-	ssize_t psr_status;
 
 	/* don't send info frame */
 	val = readl(dp->reg_base + ANALOGIX_DP_PKT_SEND_CTL);
@@ -998,26 +1027,10 @@ int analogix_dp_send_psr_spd(struct analogix_dp_device *dp,
 	if (!blocking)
 		return 0;
 
-	/*
-	 * db[1]!=0: entering PSR, wait for fully active remote frame buffer.
-	 * db[1]==0: exiting PSR, wait for either
-	 *  (a) ACTIVE_RESYNC - the sink "must display the
-	 *      incoming active frames from the Source device with no visible
-	 *      glitches and/or artifacts", even though timings may still be
-	 *      re-synchronizing; or
-	 *  (b) INACTIVE - the transition is fully complete.
-	 */
-	ret = readx_poll_timeout(analogix_dp_get_psr_status, dp, psr_status,
-		psr_status >= 0 &&
-		((vsc->db[1] && psr_status == DP_PSR_SINK_ACTIVE_RFB) ||
-		(!vsc->db[1] && (psr_status == DP_PSR_SINK_ACTIVE_RESYNC ||
-				 psr_status == DP_PSR_SINK_INACTIVE))),
-		1500, DP_TIMEOUT_PSR_LOOP_MS * 1000);
-	if (ret) {
-		dev_warn(dp->dev, "Failed to apply PSR %d\n", ret);
-		return ret;
-	}
-	return 0;
+	if (vsc->db[1])
+		return analogix_dp_get_psr_status(dp, DP_PSR_SINK_ACTIVE_RFB);
+	else
+		return analogix_dp_get_psr_status(dp, 0);
 }
 
 ssize_t analogix_dp_transfer(struct analogix_dp_device *dp,
-- 
2.34.1