Re: [PATCH i2c-next v9 0/5] i2c: aspeed: Add bus idle waiting logic for multi-master use cases

[Jae Hyun Yoo]

On 1/15/2019 2:47 PM, Wolfram Sang wrote:
> On Tue, Oct 30, 2018 at 02:09:11PM -0700, Jae Hyun Yoo wrote:
> > In multi-master environment, this driver's master cannot know
> > exactly when a peer master sends data to this driver's slave so a
> > case can be happened that this master tries to send data through
> > the master_xfer function but slave data from peer master is still
> > being processed by this driver. To prevent state corruption in the
> > case, this patch adds checking code if any slave operation is
> > ongoing and it waits up to the bus timeout duration before starting
> > a master_xfer operation.
> >
> > To support this change, it introduces changes on i2c-core-base to
> > make that able to read the bus timeout and master transfer retries
> > count values from device tree properties.
> >
> > Please review this patch set.
>
> Marking this as "Changes requested". I think if the mutex approach
> works, these patches become obsolete then.

Hi Wolfram,

Thanks for your touching base. I made and tested a new patch in my
local. Actually, I couldn't use a mutex because it should provide
locking between driver context and interrupt context. Instead, after
taking lots of experiments, I checked that idle waiting can be supported
by this H/W so I didn't need to use any locking method in the driver
code for multi-master handling. I'll submit a new patch tomorrow using a
different thread. Please drop this patch set.

Thanks,
Jae