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

[Jeffrey Hugo]

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.