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* [PATCH] drm/bridge: analogix_dp: return error if transfer none byte
@ 2016-11-03 10:17 Jianqun Xu
  2016-11-15 17:09 ` Sean Paul
  0 siblings, 1 reply; 4+ messages in thread
From: Jianqun Xu @ 2016-11-03 10:17 UTC (permalink / raw)
  To: airlied, seanpaul, wzz, tomeu.vizoso
  Cc: heiko, huangtao, yamada.masahiro, dri-devel, linux-kernel,
	linux-rockchip, Jianqun Xu

Reference from drm_dp_aux description (about transfer):
Upon success, the implementation should return the number of payload bytes
that were transferred, or a negative error-code on failure. Helpers
propagate errors from the .transfer() function, with the exception of
the -EBUSY error, which causes a transaction to be retried. On a short,
helpers will return -EPROTO to make it simpler to check for failure.

The analogix_dp_transfer will return num_transferred, but if there is none
byte been transferred, the return value will be 0, which means success, we
should return error-code if transfer none byte.

for (retry = 0; retry < 32; retry++) {
	err = aux->transfer(aux, &msg);
	if (err < 0) {
		if (err == -EBUSY)
			continue;

		goto unlock;
	}
}

Cc: zain wang <wzz@rock-chips.com>
Cc: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
---
 drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
index cd37ac0..303083a 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
@@ -1162,5 +1162,5 @@ 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;
+	return num_transferred > 0 ? num_transferred : -EBUSY;
 }
-- 
1.9.1

^ permalink raw reply related	[flat|nested] 4+ messages in thread
* [PATCH] drm/bridge: analogix_dp: return error if transfer none byte
@ 2016-11-16  0:13 Jianqun Xu
  0 siblings, 0 replies; 4+ messages in thread
From: Jianqun Xu @ 2016-11-16  0:13 UTC (permalink / raw)
  To: mturquette, sboyd, heiko, tomeu.vizoso, seanpaul, airlied,
	yamada.masahiro
  Cc: linux-clk, huangtao, linux-arm-kernel, dri-devel, linux-rockchip,
	linux-kernel, zhengxing, zhangqing, wzz, Jianqun Xu

Reference from drm_dp_aux description (about transfer):
Upon success, the implementation should return the number of payload bytes
that were transferred, or a negative error-code on failure. Helpers
propagate errors from the .transfer() function, with the exception of
the -EBUSY error, which causes a transaction to be retried. On a short,
helpers will return -EPROTO to make it simpler to check for failure.

The analogix_dp_transfer will return num_transferred, but if there is none
byte been transferred, the return value will be 0, which means success, we
should return error-code if transfer none byte.

for (retry = 0; retry < 32; retry++) {
	err = aux->transfer(aux, &msg);
	if (err < 0) {
		if (err == -EBUSY)
			continue;

		goto unlock;
	}
}

Cc: zain wang <wzz@rock-chips.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
---
 drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
index cd37ac0..303083a 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
@@ -1162,5 +1162,5 @@ 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;
+	return num_transferred > 0 ? num_transferred : -EBUSY;
 }
-- 
1.9.1

^ permalink raw reply related	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2016-11-16  6:08 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2016-11-03 10:17 [PATCH] drm/bridge: analogix_dp: return error if transfer none byte Jianqun Xu
2016-11-15 17:09 ` Sean Paul
2016-11-16  6:08   ` Archit Taneja
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2016-11-16  0:13 Jianqun Xu

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