linux-kernel - Re: [PATCH v3 03/12] dt-bindings: i2c: Discard i2c-slave flag from the DW I2C example

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Message-ID: <20200527120716.4dke6psqpw726wrd@mobilestation>
Date:   Wed, 27 May 2020 15:07:16 +0300
From:   Serge Semin <Sergey.Semin@...kalelectronics.ru>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
CC:     Serge Semin <fancer.lancer@...il.com>,
        Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Rob Herring <robh+dt@...nel.org>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        <linux-mips@...r.kernel.org>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 03/12] dt-bindings: i2c: Discard i2c-slave flag from
 the DW I2C example

On Wed, May 27, 2020 at 12:30:04PM +0300, Andy Shevchenko wrote:
> On Wed, May 27, 2020 at 1:00 AM Serge Semin
> <Sergey.Semin@...kalelectronics.ru> wrote:
> >
> > dtc currently doesn't support I2C_OWN_SLAVE_ADDRESS flag set in the
> > i2c "reg" property. If it is the compiler will print a warning:
> 
> Shouldn't be dtc whatever tools fixed?

See the first patch in the series.

> 
> > Warning (i2c_bus_reg): /example-2/i2c@...0000/eeprom@64: I2C bus unit address format error, expected "40000064"
> > Warning (i2c_bus_reg): /example-2/i2c@...0000/eeprom@64:reg: I2C address must be less than 10-bits, got "0x40000064"
> >
> > In order to silence dtc up let's discard the flag from the DW I2C DT
> > binding example for now. Just revert this commit when dtc is fixed.
> 
> Doesn't sound like a good idea. If user happens in between of these
> ping-pong change, how they will know this subtle issue?

As I see it, there are three ways we can follow.
1) Apply the patch and revert when dtc is fixed.
2) Apply the patch, but add a comment above the property, that we need
   to get the 0x40000064 address back when dtc is dixed.
3) Leave this ugly warning be until dtc is fixed.

In a comment to v2 Rob mentioned a solution like 1). Personally I am ok with
either, though I'd like to see a Rob's final comment about this.

-Sergey 

> 
> -- 
> With Best Regards,
> Andy Shevchenko