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FROMLIST: drm/bridge: analogix_dp: Don't return -EBUSY when msg->size is 0 in aux transaction

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The analogix_dp_transfer() will return -EBUSY if num_transferred is zero.
But sometimes we will send a bare address packet to start the transaction,
like drm_dp_i2c_xfer() show:
	......
	/* Send a bare address packet to start the transaction.
	 * Zero sized messages specify an address only (bare
	 * address) transaction.
	 */
	msg.buffer = NULL;
	msg.size = 0;
	err = drm_dp_i2c_do_msg(aux, &msg);
	......

In this case, the msg->size is zero, so the num_transferred will be zero too.
We can't return -EBUSY here, let's we return num_transferred if num_transferred
equals msg->size.

BUG=chrome-os-partner:57501
TEST="gooftool probe --comps display_panel"

Change-Id: Ie09f26b2c31e2406d21233afd8677337de5e77f2
Signed-off-by: zain wang <wzz@rock-chips.com>
(am from https://patchwork.kernel.org/patch/9569045/)
Reviewed-on: https://chromium-review.googlesource.com/414674
Commit-Ready: Caesar Wang <wxt@rock-chips.com>
Tested-by: 征增 王 <wzz@rock-chips.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
This commit is contained in:
zain wang
2017-02-13 16:37:33 +08:00
committed by Tao Huang
parent 0173eec295
commit ec64749b4e
1 changed files with 1 additions and 1 deletions
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2
drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
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@@ -1134,7 +1134,7 @@ ssize_t analogix_dp_transfer(struct analogix_dp_device *dp,
(msg->request & ~DP_AUX_I2C_MOT) == DP_AUX_NATIVE_READ)
msg->reply = DP_AUX_NATIVE_REPLY_ACK;
return num_transferred > 0 ? num_transferred : -EBUSY;
return (num_transferred == msg->size) ? num_transferred : -EBUSY;
aux_error:
/* if aux err happen, reset aux */