[Intel-gfx] [PATCH 6/8] drm/i915: Remove remaining retries from intel_dp_aux_ch.

[Rodrigo Vivi]

drm level already takes care of the needed retries so instead of
duplicate the effort here.

If the retry is possible immediately we return EAGAIN. Otherwise,
if we have no idea what caused the error let's assume something
was busy and let drm level handle the wait and retries.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 64 ++++++++++++++++++++++-------------------
 1 file changed, 35 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index a8ba243..35048d6 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -795,7 +795,7 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
 	uint32_t aux_clock_divider;
 	int i, ret, recv_bytes;
 	uint32_t status;
-	int try, clock = 0;
+	int clock = 0;
 	bool has_aux_irq = HAS_AUX_IRQ(dev);
 	bool vdd;
 
@@ -835,41 +835,47 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
 							  send_bytes,
 							  aux_clock_divider);
 
-		/* Must try at least 3 times according to DP spec */
-		for (try = 0; try < 5; try++) {
-			/* Load the send data into the aux channel data registers */
-			for (i = 0; i < send_bytes; i += 4)
-				I915_WRITE(intel_dp->aux_ch_data_reg[i >> 2],
-					   intel_dp_pack_aux(send + i,
-							     send_bytes - i));
+		/* Load the send data into the aux channel data registers */
+		for (i = 0; i < send_bytes; i += 4)
+			I915_WRITE(intel_dp->aux_ch_data_reg[i >> 2],
+				   intel_dp_pack_aux(send + i,
+						     send_bytes - i));
 
-			/* Send the command and wait for it to complete */
-			I915_WRITE(ch_ctl, send_ctl);
+		/* Send the command and wait for it to complete */
+		I915_WRITE(ch_ctl, send_ctl);
 
-			status = intel_dp_aux_wait_done(intel_dp, has_aux_irq);
+		status = intel_dp_aux_wait_done(intel_dp, has_aux_irq);
 
-			/* Clear done status and any errors */
-			I915_WRITE(ch_ctl,
-				   status |
-				   DP_AUX_CH_CTL_DONE |
-				   DP_AUX_CH_CTL_TIME_OUT_ERROR |
-				   DP_AUX_CH_CTL_RECEIVE_ERROR);
+		/* Clear done status and any errors */
+		I915_WRITE(ch_ctl,
+			   status |
+			   DP_AUX_CH_CTL_DONE |
+			   DP_AUX_CH_CTL_TIME_OUT_ERROR |
+			   DP_AUX_CH_CTL_RECEIVE_ERROR);
 
-			if (status & DP_AUX_CH_CTL_TIME_OUT_ERROR)
-				continue;
+		if (status & DP_AUX_CH_CTL_TIME_OUT_ERROR) {
+			/*
+			 * DP CTS 1.2 Core Rev 1.1, 4.2.1.1 & 4.2.1.2
+			 * 400us delay required for errors and timeouts
+			 * Timeout errors from the HW already meet this
+			 * requirement so skip to next iteration
+			 */
+			ret = -EAGAIN;
+			goto out;
+		}
 
-			/* DP CTS 1.2 Core Rev 1.1, 4.2.1.1 & 4.2.1.2
-			 *   400us delay required for errors and timeouts
-			 *   Timeout errors from the HW already meet this
-			 *   requirement so skip to next iteration
+		if (status & DP_AUX_CH_CTL_RECEIVE_ERROR) {
+			/*
+			 * We don't know what caused the error, so let's
+			 * return -EBUSY so drm level takes care of
+			 * the necessary wait for recover and retries
 			 */
-			if (status & DP_AUX_CH_CTL_RECEIVE_ERROR) {
-				usleep_range(400, 500);
-				continue;
-			}
-			if (status & DP_AUX_CH_CTL_DONE)
-				goto done;
+			ret = -EBUSY;
+			goto out;
 		}
+
+		if (status & DP_AUX_CH_CTL_DONE)
+			goto done;
 	}
 
 	if ((status & DP_AUX_CH_CTL_DONE) == 0) {
-- 
2.4.3