linux-kernel - Re: [PATCH v3 0/4] P2040/P2041 i2c recovery erratum

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Date:   Tue, 11 May 2021 22:10:21 +0000
From:   Joakim Tjernlund <Joakim.Tjernlund@...inera.com>
To:     "andy.shevchenko@...il.com" <andy.shevchenko@...il.com>,
        "andriy.shevchenko@...ux.intel.com" 
        <andriy.shevchenko@...ux.intel.com>,
        "mpe@...erman.id.au" <mpe@...erman.id.au>,
        "chris.packham@...iedtelesis.co.nz" 
        <chris.packham@...iedtelesis.co.nz>,
        "wsa@...nel.org" <wsa@...nel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>
CC:     "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 0/4] P2040/P2041 i2c recovery erratum

On Wed, 2021-05-12 at 09:20 +1200, Chris Packham wrote:
> The P2040/P2041 has an erratum where the i2c recovery scheme
> documented in the reference manual (and currently implemented
> in the i2c-mpc.c driver) does not work. The errata document
> provides an alternative that does work. This series implements
> that alternative and uses a property in the devicetree to
> decide when the alternative mechanism is needed.
> 
> Chris Packham (4):
>   dt-bindings: i2c: mpc: Add fsl,i2c-erratum-a004447 flag
>   powerpc/fsl: set fsl,i2c-erratum-a004447 flag for P2041 i2c
>     controllers
>   powerpc/fsl: set fsl,i2c-erratum-a004447 flag for P1010 i2c
>     controllers
>   i2c: mpc: implement erratum A-004447 workaround
> 
>  .../devicetree/bindings/i2c/i2c-mpc.yaml      |  7 ++
>  arch/powerpc/boot/dts/fsl/p1010si-post.dtsi   |  8 ++
>  arch/powerpc/boot/dts/fsl/p2041si-post.dtsi   | 16 ++++
>  drivers/i2c/busses/i2c-mpc.c                  | 81 ++++++++++++++++++-
>  4 files changed, 110 insertions(+), 2 deletions(-)
> 

This now reminds me about the current I2C reset procedure, it didn't work for us and I came up with this one:
  https://www.spinics.net/lists/linux-i2c/msg29490.html
it never got in but we are still using it.

  Jocke