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Commit 25377b92 authored by Alex Deucher's avatar Alex Deucher Committed by Christian König
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drm/radeon/dp: handle zero sized i2c over aux transactions (v2) 



Needed for proper i2c over aux handling for certain
monitors and configurations (e.g., dp bridges or
adapters).

v2: add comments clarifying tx_size setting.

Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
parent a6c8aff0

drivers/gpu/drm/radeon/atombios_dp.c

+18 −5
Original line number Diff line number Diff line
@@ -142,7 +142,8 @@ static int radeon_process_aux_ch(struct radeon_i2c_chan *chan, 
	return recv_bytes;

}



#define HEADER_SIZE 4

#define BARE_ADDRESS_SIZE 3

#define HEADER_SIZE (BARE_ADDRESS_SIZE + 1)



static ssize_t

radeon_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
@@ -160,12 +161,18 @@ radeon_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) 
	tx_buf[0] = msg->address & 0xff;

	tx_buf[1] = msg->address >> 8;

	tx_buf[2] = msg->request << 4;

	tx_buf[3] = msg->size - 1;

	tx_buf[3] = msg->size ? (msg->size - 1) : 0;



	switch (msg->request & ~DP_AUX_I2C_MOT) {

	case DP_AUX_NATIVE_WRITE:

	case DP_AUX_I2C_WRITE:

		/* tx_size needs to be 4 even for bare address packets since the atom

		 * table needs the info in tx_buf[3].

		 */

		tx_size = HEADER_SIZE + msg->size;

		if (msg->size == 0)

			tx_buf[3] |= BARE_ADDRESS_SIZE << 4;

		else

			tx_buf[3] |= tx_size << 4;

		memcpy(tx_buf + HEADER_SIZE, msg->buffer, msg->size);

		ret = radeon_process_aux_ch(chan,
@@ -176,7 +183,13 @@ radeon_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) 
		break;

	case DP_AUX_NATIVE_READ:

	case DP_AUX_I2C_READ:

		/* tx_size needs to be 4 even for bare address packets since the atom

		 * table needs the info in tx_buf[3].

		 */

		tx_size = HEADER_SIZE;

		if (msg->size == 0)

			tx_buf[3] |= BARE_ADDRESS_SIZE << 4;

		else

			tx_buf[3] |= tx_size << 4;

		ret = radeon_process_aux_ch(chan,

					    tx_buf, tx_size, msg->buffer, msg->size, delay, &ack);
@@ -186,7 +199,7 @@ radeon_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) 
		break;

	}



	if (ret > 0)

	if (ret >= 0)

		msg->reply = ack >> 4;



	return ret;