[Why]
Notice AUX request format of I2C-over-AUX with
Write_Status_Update_Request flag set is incorrect. It should
be address only request without length and data like:
"SYNC->COM3:0 (= 0110)|0000-> 0000|0000->
0|7-bit I2C address (the same as the last)-> STOP->".
[How]
Refer to DP v2.1 Table 2-178, correct the
Write_Status_Update_Request to be address only request.
Note that we might receive 0 returned by aux->transfer() when
receive reply I2C_ACK|AUX_ACK of Write_Status_Update_Request
transaction. Which indicating all data bytes get written.
We should avoid to return 0 bytes get transferred under this
case.
Fixes: 68ec2a2a2481 ("drm/dp: Use I2C_WRITE_STATUS_UPDATE to drain partial
I2C_WRITE requests")
Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
Cc: Jani Nikula <jani.nik...@intel.com>
Cc: Mario Limonciello <mario.limoncie...@amd.com>
Cc: Harry Wentland <harry.wentl...@amd.com>
Cc: sta...@vger.kernel.org
Signed-off-by: Wayne Lin <wayne....@amd.com>
---
drivers/gpu/drm/display/drm_dp_helper.c | 45 +++++++++++++++++++++----
1 file changed, 38 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
index 57828f2b7b5a..0c8cba7ed875 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -1857,6 +1857,12 @@ static u32 drm_dp_i2c_functionality(struct i2c_adapter
*adapter)
I2C_FUNC_10BIT_ADDR;
}
+static inline bool
+drm_dp_i2c_msg_is_write_status_update(struct drm_dp_aux_msg *msg)
+{
+ return ((msg->request & ~DP_AUX_I2C_MOT) ==
DP_AUX_I2C_WRITE_STATUS_UPDATE);
+}
+
static void drm_dp_i2c_msg_write_status_update(struct drm_dp_aux_msg *msg)
{
/*
@@ -1965,6 +1971,7 @@ MODULE_PARM_DESC(dp_aux_i2c_speed_khz,
static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg
*msg)
{
unsigned int retry, defer_i2c;
+ struct drm_dp_aux_msg orig_msg = *msg;
int ret;
/*
* DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device
@@ -1976,6 +1983,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux,
struct drm_dp_aux_msg *msg)
int max_retries = max(7, drm_dp_i2c_retry_count(msg,
dp_aux_i2c_speed_khz));
for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c);
retry++) {
+ if (drm_dp_i2c_msg_is_write_status_update(msg)) {
+ /* Address only transaction */
+ msg->buffer = NULL;
+ msg->size = 0;
+ }
+
ret = aux->transfer(aux, msg);
if (ret < 0) {
if (ret == -EBUSY)
@@ -1993,7 +2006,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux,
struct drm_dp_aux_msg *msg)
else
drm_dbg_kms(aux->drm_dev, "%s: transaction
failed: %d\n",
aux->name, ret);
- return ret;
+ goto out;
}
@@ -2008,7 +2021,8 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux,
struct drm_dp_aux_msg *msg)
case DP_AUX_NATIVE_REPLY_NACK:
drm_dbg_kms(aux->drm_dev, "%s: native nack (result=%d,
size=%zu)\n",
aux->name, ret, msg->size);
- return -EREMOTEIO;
+ ret = -EREMOTEIO;
+ goto out;
case DP_AUX_NATIVE_REPLY_DEFER:
drm_dbg_kms(aux->drm_dev, "%s: native defer\n",
aux->name);
@@ -2027,24 +2041,35 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux,
struct drm_dp_aux_msg *msg)
default:
drm_err(aux->drm_dev, "%s: invalid native reply
%#04x\n",
aux->name, msg->reply);
- return -EREMOTEIO;
+ ret = -EREMOTEIO;
+ goto out;
}
switch (msg->reply & DP_AUX_I2C_REPLY_MASK) {
case DP_AUX_I2C_REPLY_ACK:
+ /*
+ * When I2C write firstly get defer and get ack after
+ * retries by wirte_status_update, we have to return
+ * all data bytes get transferred instead of 0.
+ */
+ if (drm_dp_i2c_msg_is_write_status_update(msg) && ret
== 0)
+ ret = orig_msg.size;
+
/*
* Both native ACK and I2C ACK replies received. We
* can assume the transfer was successful.
*/
if (ret != msg->size)
drm_dp_i2c_msg_write_status_update(msg);
- return ret;
+
+ goto out;
case DP_AUX_I2C_REPLY_NACK:
drm_dbg_kms(aux->drm_dev, "%s: I2C nack (result=%d,
size=%zu)\n",
aux->name, ret, msg->size);
aux->i2c_nack_count++;
- return -EREMOTEIO;
+ ret = -EREMOTEIO;
+ goto out;
case DP_AUX_I2C_REPLY_DEFER:
drm_dbg_kms(aux->drm_dev, "%s: I2C defer\n", aux->name);
@@ -2063,12 +2088,18 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux,
struct drm_dp_aux_msg *msg)
default:
drm_err(aux->drm_dev, "%s: invalid I2C reply %#04x\n",
aux->name, msg->reply);
- return -EREMOTEIO;
+ ret = -EREMOTEIO;
+ goto out;
}
}
drm_dbg_kms(aux->drm_dev, "%s: Too many retries, giving up\n",
aux->name);
- return -EREMOTEIO;
+ ret = -EREMOTEIO;
+out:
+ /* In case we change original msg by Write_Status_Update*/
+ msg->buffer = orig_msg.buffer;
+ msg->size = orig_msg.size;
+ return ret;
}
static void drm_dp_i2c_msg_set_request(struct drm_dp_aux_msg *msg,
--
2.43.0
