Re: [PATCH] mhi_bus: core: Return EBUSY if MHI ring is full

From: Jeffrey Hugo
Date: Tue Feb 16 2021 - 15:54:54 EST


On 2/16/2021 1:22 PM, Bhaumik Bhatt wrote:
On 2021-02-16 10:48 AM, Jeffrey Hugo wrote:
From: Fan Wu <wufan@xxxxxxxxxxxxxx>

Currently ENOMEM is returned when MHI ring is full. This error code is
very misleading. Change to EBUSY instead.

Signed-off-by: Fan Wu <wufan@xxxxxxxxxxxxxx>
Signed-off-by: Jeffrey Hugo <jhugo@xxxxxxxxxxxxxx>
---
 drivers/bus/mhi/core/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index f182736..21eb5fc 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -996,7 +996,7 @@ static int mhi_queue(struct mhi_device *mhi_dev,
struct mhi_buf_info *buf_info,

     ret = mhi_is_ring_full(mhi_cntrl, tre_ring);
     if (unlikely(ret)) {
-        ret = -ENOMEM;
+        ret = -EBUSY;
         goto exit_unlock;
     }

ENOMEM is descriptive of the state of the ring since you basically cannot queue any
more packets as no memory is currently available.

But I agree, it can be misleading for this API. How about EAGAIN in place of EBUSY,
which tells the user to try the queue attempt again implying memory should become
available as more elements are consumed by the device/client?

Fan and I think EAGAIN is fine. Will send a v2.

--
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.