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    SubjectRe: [PATCH AUTOSEL 5.12 42/43] powerpc/fsl: set fsl,i2c-erratum-a004447 flag for P2041 i2c controllers
    Date
    Sasha Levin <sashal@kernel.org> writes:
    > From: Chris Packham <chris.packham@alliedtelesis.co.nz>
    >
    > [ Upstream commit 7adc7b225cddcfd0f346d10144fd7a3d3d9f9ea7 ]
    >
    > The i2c controllers on the P2040/P2041 have an erratum where the
    > documented scheme for i2c bus recovery will not work (A-004447). A
    > different mechanism is needed which is documented in the P2040 Chip
    > Errata Rev Q (latest available at the time of writing).
    >
    > Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
    > Acked-by: Michael Ellerman <mpe@ellerman.id.au>
    > Signed-off-by: Wolfram Sang <wsa@kernel.org>
    > Signed-off-by: Sasha Levin <sashal@kernel.org>
    > ---
    > arch/powerpc/boot/dts/fsl/p2041si-post.dtsi | 16 ++++++++++++++++
    > 1 file changed, 16 insertions(+)

    This patch (and the subsequent one), just set a flag in the device tree.

    They have no effect unless you also backport the code change that looks
    for that flag, which was upstream commit:

    8f0cdec8b5fd ("i2c: mpc: implement erratum A-004447 workaround")

    AFAICS you haven't picked that one up for any of the stable trees.

    I'll defer to Chris & Wolfram on whether it's a good idea to take the
    code change for stable.

    I guess it's harmless to pick these two patches, but it's also
    pointless. So I think you either want to take all three, or drop these
    two.

    cheers

    > diff --git a/arch/powerpc/boot/dts/fsl/p2041si-post.dtsi b/arch/powerpc/boot/dts/fsl/p2041si-post.dtsi
    > index 872e4485dc3f..ddc018d42252 100644
    > --- a/arch/powerpc/boot/dts/fsl/p2041si-post.dtsi
    > +++ b/arch/powerpc/boot/dts/fsl/p2041si-post.dtsi
    > @@ -371,7 +371,23 @@ sdhc@114000 {
    > };
    >
    > /include/ "qoriq-i2c-0.dtsi"
    > + i2c@118000 {
    > + fsl,i2c-erratum-a004447;
    > + };
    > +
    > + i2c@118100 {
    > + fsl,i2c-erratum-a004447;
    > + };
    > +
    > /include/ "qoriq-i2c-1.dtsi"
    > + i2c@119000 {
    > + fsl,i2c-erratum-a004447;
    > + };
    > +
    > + i2c@119100 {
    > + fsl,i2c-erratum-a004447;
    > + };
    > +
    > /include/ "qoriq-duart-0.dtsi"
    > /include/ "qoriq-duart-1.dtsi"
    > /include/ "qoriq-gpio-0.dtsi"
    > --
    > 2.30.2

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