Commit 245ce70c authored by Thierry Reding's avatar Thierry Reding
Browse files

drm/tegra: dpaux: Retry on transfer size mismatch 



When a transfer didn't complete transmission of the requested number of
bytes, signal that the transaction should be retried.

Signed-off-by: default avatarThierry Reding <treding@nvidia.com>
parent 5e881f6b

drivers/gpu/drm/tegra/dpaux.c

+18 −7
Original line number Diff line number Diff line
@@ -121,6 +121,7 @@ static ssize_t tegra_dpaux_transfer(struct drm_dp_aux *aux, 
	struct tegra_dpaux *dpaux = to_dpaux(aux);

	unsigned long status;

	ssize_t ret = 0;

	u8 reply = 0;

	u32 value;



	/* Tegra has 4x4 byte DP AUX transmit and receive FIFOs. */
@@ -215,23 +216,23 @@ static ssize_t tegra_dpaux_transfer(struct drm_dp_aux *aux, 


	switch ((value & DPAUX_DP_AUXSTAT_REPLY_TYPE_MASK) >> 16) {

	case 0x00:

		msg->reply = DP_AUX_NATIVE_REPLY_ACK;

		reply = DP_AUX_NATIVE_REPLY_ACK;

		break;



	case 0x01:

		msg->reply = DP_AUX_NATIVE_REPLY_NACK;

		reply = DP_AUX_NATIVE_REPLY_NACK;

		break;



	case 0x02:

		msg->reply = DP_AUX_NATIVE_REPLY_DEFER;

		reply = DP_AUX_NATIVE_REPLY_DEFER;

		break;



	case 0x04:

		msg->reply = DP_AUX_I2C_REPLY_NACK;

		reply = DP_AUX_I2C_REPLY_NACK;

		break;



	case 0x08:

		msg->reply = DP_AUX_I2C_REPLY_DEFER;

		reply = DP_AUX_I2C_REPLY_DEFER;

		break;

	}
@@ -239,14 +240,24 @@ static ssize_t tegra_dpaux_transfer(struct drm_dp_aux *aux, 
		if (msg->request & DP_AUX_I2C_READ) {

			size_t count = value & DPAUX_DP_AUXSTAT_REPLY_MASK;



			if (WARN_ON(count != msg->size))

				count = min_t(size_t, count, msg->size);

			/*

			 * There might be a smarter way to do this, but since

			 * the DP helpers will already retry transactions for

			 * an -EBUSY return value, simply reuse that instead.

			 */

			if (count != msg->size) {

				ret = -EBUSY;

				goto out;

			}



			tegra_dpaux_read_fifo(dpaux, msg->buffer, count);

			ret = count;

		}

	}



	msg->reply = reply;



out:

	return ret;

}