[PATCH linux dev-4.13 0/2] Fix SBEFIFO chardev read behaviour

[Andrew Jeffery]

Hi Eddie,

On Tue, 15 May 2018, at 07:57, Eddie James wrote:
> 
> 
> On 05/14/2018 01:18 AM, Andrew Jeffery wrote:
> > Hello,
> >
> > read() on the SBEFIFO chardevs is currently unusuable as it will always return
> > -EAGAIN on a read subsequent to the EOT flag being observed. This breaks reads
> > using short buffers as we now have no way to know when we have received the
> > entire message. This is made infinitely worse by the protocol, which as
> > defined, means we cannot know how much data must be read, and therefore all
> > buffers are effectively short*.
> >
> > These two patches help by at least returning 0 for a read subsequent to one
> > which drains the last byte from the transfer buffer. A read subsequent to one
> > returning 0 will then return -EAGAIN if necessary, under the expectation that a
> > write() has been issued.
> 
> Thanks Andrew, I haven't dug into the diffs too much but I just tested 
> the series and it appears to have made the in-kernel API less reliable. 
> I'm getting some errors when attempting to use the OCC driver.

Thanks for testing. What errors are you sometimes seeing? I need some more info to reproduce and understand what might be going wrong.

Cheers,

Andrew