[PATCH v2 5/5] i2c: davinci: use ICPFUNC to toggle I2C as gpio for bus recovery
wsa at the-dreams.de
Tue Jul 7 07:13:12 PDT 2015
On Tue, Jul 07, 2015 at 03:48:52PM +0200, Uwe Kleine-König wrote:
> On Tue, Jul 07, 2015 at 03:37:49PM +0200, Jan Lübbe wrote:
> > On Mi, 2014-11-26 at 19:05 +0200, Grygorii Strashko wrote:
> > > On 11/26/2014 06:04 PM, Uwe Kleine-König wrote:
> > > > On Wed, Nov 26, 2014 at 03:59:53PM +0200, Grygorii Strashko wrote:
> > > >> Having a board where the I2C bus locks up occasionally made it clear
> > > >> that the bus recovery in the i2c-davinci driver will only work on
> > > >> some boards, because on regular boards, this will only toggle GPIO
> > > >> lines that aren't muxed to the actual pins.
> > > >>
> > > >> The I2C controller on SoCs like da850 (and da830), Keystone 2 has the
> > > >> built-in capability to bit-bang its lines by using the ICPFUNC registers
> > > >> of the i2c controller.
> > > >> Implement the suggested procedure by toggling SCL and checking SDA using
> > > >> the ICPFUNC registers of the I2C controller when present. Allow platforms
> > > >> to indicate the presence of the ICPFUNC registers with a has_pfunc platform
> > > >> data flag and add optional DT property "ti,has-pfunc" to indicate
> > > >> the same in DT.
> > > > On what does it depend if this pfunc stuff works or not? Only the SoC,
> > > > or also on some board specific properties?
> > >
> > > SoC / set of SoCs. Also, similar feature is supported by OMAP and AM335x/AM437x SoCs
> > > using I2C_SYSTEST register.
> > >
> > > > Given the former using the
> > > > compatible string to detect its availability would be better. (In this
> > > > case also sorry, didn't consider this case when requesting the property
> > > > in the last round.)
> > I only stumbled across this after it was merged, with the additional
> I also wonder how it came to the Reviewed-by tag for me. The last thing
> that I said about the patch was "On what does it depend if this pfunc
> stuff works or not? Only the SoC, or also on some board specific
> properties?" (see above) and "the patch looks ok". IMHO this hardly
> justifies to add the Reviewed-by tag for the next round. :-(
That needs to be discussed with Grygorii. I can't verify the correctness
of tags for every patch, although I do try to keep an eye on it...
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