Commit 68ec2a2a authored by Ville Syrjälä's avatar Ville Syrjälä Committed by Daniel Vetter
Browse files

drm/dp: Use I2C_WRITE_STATUS_UPDATE to drain partial I2C_WRITE requests 



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: default avatarAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: default avatarJani Nikula <jani.nikula@intel.com>
Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
[danvet: Resolve conflict due to changed context.]
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent f9934061

drivers/gpu/drm/drm_dp_helper.c

+39 −4
Original line number Diff line number Diff line
@@ -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;

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