drm/i915: Clarify error returns from display port aux channel I/O

Use distinct error return values for each kind of aux channel I/O failure.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 13 insertions, 7 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 3f8d7b449e7..818fe34f2b5 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -209,15 +209,19 @@ intel_dp_aux_ch(struct intel_output *intel_output,
 
         if ((status & DP_AUX_CH_CTL_DONE) == 0) {
                 printk(KERN_ERR "dp_aux_ch not done status 0x%08x\n", status);
-                return -1;
+                return -EBUSY;
         }
 
         /* Check for timeout or receive error.
          * Timeouts occur when the sink is not connected
          */
-        if (status & (DP_AUX_CH_CTL_TIME_OUT_ERROR | DP_AUX_CH_CTL_RECEIVE_ERROR)) {
-                printk(KERN_ERR "dp_aux_ch error status 0x%08x\n", status);
-                return -1;
+        if (status & DP_AUX_CH_CTL_RECEIVE_ERROR) {
+                printk(KERN_ERR "dp_aux_ch receive error status 0x%08x\n", status);
+                return -EIO;
+        }
+        if (status & DP_AUX_CH_CTL_TIME_OUT_ERROR) {
+                printk(KERN_ERR "dp_aux_ch timeout status 0x%08x\n", status);
+                return -ETIMEDOUT;
         }
 
         /* Unload any bytes sent back from the other side */
@@ -263,7 +267,7 @@ intel_dp_aux_native_write(struct intel_output *intel_output,
                 else if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_DEFER)
                         udelay(100);
                 else
-                        return -1;
+                        return -EIO;
         }
         return send_bytes;
 }
@@ -299,7 +303,9 @@ intel_dp_aux_native_read(struct intel_output *intel_output,
         for (;;) {
                 ret = intel_dp_aux_ch(intel_output, msg, msg_bytes,
                                       reply, reply_bytes);
-                if (ret <= 0)
+                if (ret == 0)
+                        return -EPROTO;
+                if (ret < 0)
                         return ret;
                 ack = reply[0];
                 if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_ACK) {
@@ -309,7 +315,7 @@ intel_dp_aux_native_read(struct intel_output *intel_output,
                 else if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_DEFER)
                         udelay(100);
                 else
-                        return -1;
+                        return -EIO;
         }
 }