[PATCH 14/14] drm/bridge: analogix_dp: handle AUX transfer timeouts

[Lucas Stach]

Timeouts on the AUX bus are to be expected in certain normal operating
conditions. There is no need to raise an error log or re-initialize the
whole AUX state machine. Simply acknowledge the AUX_ERR interrupt and
let upper layers know about the timeout.

Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
---
 drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c | 3 +++
 drivers/gpu/drm/bridge/analogix/analogix_dp_reg.h | 9 +++++++++
 2 files changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
index 0f016dca9f3d..3afc73c858c4 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
@@ -1016,6 +1016,9 @@ ssize_t analogix_dp_transfer(struct analogix_dp_device *dp,
 
 		writel(AUX_ERR, dp->reg_base + ANALOGIX_DP_INT_STA);
 
+		if (aux_status == AUX_STATUS_TIMEOUT_ERROR)
+			return -ETIMEDOUT;
+
 		dev_warn(dp->dev, "AUX CH error happened: %#x (%d)\n",
 			 aux_status, !!(reg & AUX_ERR));
 		goto aux_error;
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.h b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.h
index e284ee8da58b..12735139046c 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.h
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.h
@@ -361,6 +361,15 @@
 /* ANALOGIX_DP_AUX_CH_STA */
 #define AUX_BUSY				(0x1 << 4)
 #define AUX_STATUS_MASK				(0xf << 0)
+#define AUX_STATUS_OK				(0x0 << 0)
+#define AUX_STATUS_NACK_ERROR			(0x1 << 0)
+#define AUX_STATUS_TIMEOUT_ERROR		(0x2 << 0)
+#define AUX_STATUS_UNKNOWN_ERROR		(0x3 << 0)
+#define AUX_STATUS_MUCH_DEFER_ERROR		(0x4 << 0)
+#define AUX_STATUS_TX_SHORT_ERROR		(0x5 << 0)
+#define AUX_STATUS_RX_SHORT_ERROR		(0x6 << 0)
+#define AUX_STATUS_NACK_WITHOUT_M_ERROR		(0x7 << 0)
+#define AUX_STATUS_I2C_NACK_ERROR		(0x8 << 0)
 
 /* ANALOGIX_DP_AUX_CH_DEFER_CTL */
 #define DEFER_CTRL_EN				(0x1 << 7)
-- 
2.39.2