Re: [PATCH 1/4] drm/radeon/dp: handle zero sized i2c over aux transactions

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Am 04.04.2014 21:58, schrieb Alex Deucher:
Needed for proper i2c over aux handling for certain
monitors and configurations (e.g., dp bridges or
adapters).

Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>

My planning was that yesterdays pull request is the last one with new features. I can't judge how invasive this series is, so should I add it to my 3.15 branch and send Dave another pull request or should we wait for 3.16?

Christian.

---
  drivers/gpu/drm/radeon/atombios_dp.c | 15 +++++++++++----
  1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index 8b0ab17..e914008 100644
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -143,6 +143,7 @@ static int radeon_process_aux_ch(struct radeon_i2c_chan *chan,
  }
#define HEADER_SIZE 4
+#define BARE_ADDRESS_SIZE 3
static ssize_t
  radeon_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
@@ -160,13 +161,16 @@ 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 = HEADER_SIZE + msg->size;
-		tx_buf[3] |= tx_size << 4;
+		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,
  					    tx_buf, tx_size, NULL, 0, delay, &ack);
@@ -177,7 +181,10 @@ radeon_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
  	case DP_AUX_NATIVE_READ:
  	case DP_AUX_I2C_READ:
  		tx_size = HEADER_SIZE;
-		tx_buf[3] |= tx_size << 4;
+		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);
  		break;
@@ -186,7 +193,7 @@ 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;

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