drm/i915/dp: return number of bytes written for short aux/i2c writes
Allow for a larger receive data size, and check if the receiver returned
the number of bytes written. Without this, we've basically skipped all
the unwritten bytes for short writes.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 5256c06..3967af1 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -951,7 +951,7 @@
case DP_AUX_NATIVE_WRITE:
case DP_AUX_I2C_WRITE:
txsize = msg->size ? HEADER_SIZE + msg->size : BARE_ADDRESS_SIZE;
- rxsize = 1;
+ rxsize = 2; /* 0 or 1 data bytes */
if (WARN_ON(txsize > 20))
return -E2BIG;
@@ -962,8 +962,13 @@
if (ret > 0) {
msg->reply = rxbuf[0] >> 4;
- /* Return payload size. */
- ret = msg->size;
+ if (ret > 1) {
+ /* Number of bytes written in a short write. */
+ ret = clamp_t(int, rxbuf[1], 0, msg->size);
+ } else {
+ /* Return payload size. */
+ ret = msg->size;
+ }
}
break;