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drm/dp: Use I2C_WRITE_STATUS_UPDATE to drain partial I2C_WRITE requests

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When an i2c WRITE gets an i2c defer or short i2c ack reply, we are
supposed to switch the request from I2C_WRITE to I2C_WRITE_STATUS_UPDATE
when we continue to poll for the completion of the request.

v2: Don't assume DP_AUX_I2C_WRITE is 0 even though it is, to make the
    code more obvious to the casual reader (Jani)

Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
[danvet: Resolve conflict due to changed context.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Ville Syrjälä 2015-08-27 17:23:30 +03:00 committed by Daniel Vetter
parent f993406182
commit 68ec2a2a24
1 changed files with 39 additions and 4 deletions
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43
drivers/gpu/drm/drm_dp_helper.c
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@ -422,6 +422,19 @@ static u32 drm_dp_i2c_functionality(struct i2c_adapter *adapter)
I2C_FUNC_10BIT_ADDR;
}
static void drm_dp_i2c_msg_write_status_update(struct drm_dp_aux_msg *msg)
{
/*
* In case of i2c defer or short i2c ack reply to a write,
* we need to switch to WRITE_STATUS_UPDATE to drain the
* rest of the message
*/
if ((msg->request & ~DP_AUX_I2C_MOT) == DP_AUX_I2C_WRITE) {
msg->request &= DP_AUX_I2C_MOT;
msg->request |= DP_AUX_I2C_WRITE_STATUS_UPDATE;
}
}
/*
* Transfer a single I2C-over-AUX message and handle various error conditions,
* retrying the transaction as appropriate. It is assumed that the
@ -490,6 +503,8 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
* 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;
case DP_AUX_I2C_REPLY_NACK:
@ -507,6 +522,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
if (defer_i2c < 7)
defer_i2c++;
usleep_range(400, 500);
drm_dp_i2c_msg_write_status_update(msg);
continue;
default:
@ -519,6 +535,14 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
return -EREMOTEIO;
}
static void drm_dp_i2c_msg_set_request(struct drm_dp_aux_msg *msg,
const struct i2c_msg *i2c_msg)
{
msg->request = (i2c_msg->flags & I2C_M_RD) ?
DP_AUX_I2C_READ : DP_AUX_I2C_WRITE;
msg->request |= DP_AUX_I2C_MOT;
}
/*
* Keep retrying drm_dp_i2c_do_msg until all data has been transferred.
*
@ -572,10 +596,7 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
for (i = 0; i < num; i++) {
msg.address = msgs[i].addr;
msg.request = (msgs[i].flags & I2C_M_RD) ?
DP_AUX_I2C_READ :
DP_AUX_I2C_WRITE;
msg.request |= DP_AUX_I2C_MOT;
drm_dp_i2c_msg_set_request(&msg, &msgs[i]);
/* Send a bare address packet to start the transaction.
* Zero sized messages specify an address only (bare
* address) transaction.
@ -583,6 +604,13 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
msg.buffer = NULL;
msg.size = 0;
err = drm_dp_i2c_do_msg(aux, &msg);
/*
* Reset msg.request in case in case it got
* changed into a WRITE_STATUS_UPDATE.
*/
drm_dp_i2c_msg_set_request(&msg, &msgs[i]);
if (err < 0)
break;
/* We want each transaction to be as large as possible, but
@ -595,6 +623,13 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
msg.size = min(transfer_size, msgs[i].len - j);
err = drm_dp_i2c_drain_msg(aux, &msg);
/*
* Reset msg.request in case in case it got
* changed into a WRITE_STATUS_UPDATE.
*/
drm_dp_i2c_msg_set_request(&msg, &msgs[i]);
if (err < 0)
break;
transfer_size = err;