Re: [PATCH] i2c: designware: Fix failure on baytrail

[Jarkko Nikula <jarkko.nikula@linux.intel.com>]

Hi

On 02/09/2018 05:07 PM, Ben Gardner wrote:
> I bisected the kernel to try to find where this broke, but the answer
> I kept on getting didn't make any sense.
> I think t was this commit:
> 
> 4d6d5f1d08d2138dc43b28966eb6200e3db2e623 i2c: designware: fix rx fifo
> depth tracking
> > Of course, reverting that one commit didn't fix anything.
> So I added a log to the dw_readl() and dw_writel() functions in both a
> working and broken kernel and compared.
> 
Yeah, it's not unusual that bisect diverts into wrong commit especially 
with issues that don't reproduce easily or if some unrelated thing is 
causing also failure at certain step leading to a wrong good/bad guess.

Can you test does reverting my guessed commit 2702ea7dbec5 ("i2c: 
designware: wait for disable/enable only if necessary") fix it?

For linux-stable it is good info to know exactly the commit causing 
regression and mark that in your changelog. It allows linux-stable folks 
to apply fix to earlier kernels and know versions this fix will still 
apply if cannot apply where regression was introduced. Fox example:

Fixes: commit 2702ea7dbec5 ("i2c: designware: wait for disable/enable 
only if necessary")
Cc: linux-stable <stable@vger.kernel.org> # 4.13+

-- 
Jarkko