linux-kernel - Re: [PATCH 0/2] i2c: at91: Add support for programmable clock source

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Date:   Wed, 13 Oct 2021 13:41:44 +0200
From:   Horatiu Vultur - M31836 <Horatiu.Vultur@...rochip.com>
To:     Codrin Ciubotariu - M19940 <Codrin.Ciubotariu@...rochip.com>
CC:     "robh+dt@...nel.org" <robh+dt@...nel.org>,
        Nicolas Ferre - M43238 <Nicolas.Ferre@...rochip.com>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>,
        Ludovic Desroches - M43218 <Ludovic.Desroches@...rochip.com>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/2] i2c: at91: Add support for programmable clock source

The 10/13/2021 08:49, Codrin Ciubotariu - M19940 wrote:
> On 12.10.2021 17:07, Horatiu Vultur wrote:
> > Add support to be able to set BRSRCCLK. This feature is support on lan966x
> > 
> > Horatiu Vultur (2):
> >    dt-bindings: i2c: at91: Extend compatible list for lan966x
> >    i2c: at91: add support for brsrcclk
> > 
> >   .../devicetree/bindings/i2c/i2c-at91.txt      |  6 +++--
> >   drivers/i2c/busses/i2c-at91-core.c            | 16 +++++++++++++
> >   drivers/i2c/busses/i2c-at91-master.c          | 23 +++++++++++++++++--
> >   drivers/i2c/busses/i2c-at91.h                 |  1 +
> >   4 files changed, 42 insertions(+), 4 deletions(-)
> > 
> 
> Hi Horatiu,

Hi Codrin,

> 
>  From what I understand, on your DTS, you replaced the peripheral clock 
> with the GCLK in the I2C node. This means that you are forcing all the 
> variants that support clk_brsrcclk to treat the current clock as GCLK. 
> This is not necessarily correct, since this newer variants can also work 
> fine with only the peripheral clock and we should keep these option 
> available.
> 
> I would add an optional GCLK clock binding in the I2C node. This way 
> GCLK will be used only if it is present in DT and clk_brsrcclk set.

Thanks for the explanation.

I think actually I will drop this patch series because apparently
lan966x works fine also with the peripheral clock. So then no changes
are required.

If you think is worth it, I can do another version with the proposed
changes.

> 
> Best regards,
> Codrin

-- 
/Horatiu