linux-kernel - Re: [PATCH v3 3/3] i2c: mpc: Use i2c-scl-clk-low-timeout-ms i2c property

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Date:   Tue, 14 Mar 2023 16:16:08 +0100
From:   Andi Shyti <andi.shyti@...nel.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Andi Shyti <andi.shyti@...nel.org>, linux-i2c@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Wolfram Sang <wsa@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Chris Packham <chris.packham@...iedtelesis.co.nz>,
        Ryan Chen <ryan_chen@...eedtech.com>
Subject: Re: [PATCH v3 3/3] i2c: mpc: Use i2c-scl-clk-low-timeout-ms i2c
 property

Hi,

On Tue, Mar 14, 2023 at 03:22:52PM +0100, Krzysztof Kozlowski wrote:
> On 13/03/2023 00:36, Andi Shyti wrote:
> > "fsl,timeout" is marked as deprecated and replaced by the
> > "i2c-scl-clk-low-timeout-ms" i2c property.
> > 
> > Use this latter and, in case it is missing, for back
> > compatibility, check whether we still have "fsl,timeout" defined.
> > 
> > Signed-off-by: Andi Shyti <andi.shyti@...nel.org>
> > Reviewed-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
> > ---
> >  drivers/i2c/busses/i2c-mpc.c | 12 +++++++++++-
> >  1 file changed, 11 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
> > index 87e5c1725750..28f11e30ac50 100644
> > --- a/drivers/i2c/busses/i2c-mpc.c
> > +++ b/drivers/i2c/busses/i2c-mpc.c
> > @@ -843,8 +843,18 @@ static int fsl_i2c_probe(struct platform_device *op)
> >  			mpc_i2c_setup_8xxx(op->dev.of_node, i2c, clock);
> >  	}
> >  
> > +	/*
> > +	 * "fsl,timeout" has been marked as deprecated and, to maintain
> > +	 * backward compatibility, we will only look for it if
> > +	 * "i2c-scl-clk-low-timeout-ms" is not present.
> > +	 */
> >  	result = of_property_read_u32(op->dev.of_node,
> > -				      "fsl,timeout", &mpc_ops.timeout);
> > +				      "i2c-scl-clk-low-timeout-ms",
> > +				      &mpc_ops.timeout);
> > +	if (result == -EINVAL)
> > +		result = of_property_read_u32(op->dev.of_node,
> > +					      "fsl,timeout", &mpc_ops.timeout);
> 
> Wasn't old property in us and new one is in ms?

Thanks, Krzysztof! Good catch!

Chris, you are the only user of this property, as of now. Is it
OK if we keep it ms? I will send a proper patch to do the
conversion.

To me it doesn't make much sense to have the timeout defined in
us as that's of the same order of the raising and falling time
of the clock. Any opinion?

Andi