Re: [PATCH 3/3] dt: paz00: define nvec as child of i2c bus

[Andrey Danin]

Hi,

Thanks for the review.

On 03.02.2015 0:20, Stephen Warren wrote:
> On 01/29/2015 12:20 AM, Andrey Danin wrote:
> > NVEC driver was reimplemented to use tegra i2c. Use common i2c bindings
> > for NVEC node.
>
> > diff --git a/Documentation/devicetree/bindings/nvec/nvidia,nvec.txt
> > b/Documentation/devicetree/bindings/nvec/nvidia,nvec.txt
>
> The changes to this file make more sense either as a standalone patch
> 1/4, or as part of the driver changes.
>
> > @@ -2,20 +2,5 @@ NVIDIA compliant embedded controller
> >
> >   Required properties:
> >   - compatible : should be "nvidia,nvec".
> > -- reg : the iomem of the i2c slave controller
> > -- interrupts : the interrupt line of the i2c slave controller
> > -- clock-frequency : the frequency of the i2c bus
> > -- gpios : the gpio used for ec request
> > -- slave-addr: the i2c address of the slave controller
> > -- clocks : Must contain an entry for each entry in clock-names.
> > -  See ../clocks/clock-bindings.txt for details.
> > -- clock-names : Must include the following entries:
> > -  Tegra20/Tegra30:
> > -  - div-clk
> > -  - fast-clk
> > -  Tegra114:
> > -  - div-clk
> > -- resets : Must contain an entry for each entry in reset-names.
> > -  See ../reset/reset.txt for details.
> > -- reset-names : Must include the following entries:
> > -  - i2c
> > +- request-gpios : the gpio used for ec request
> > +- reg: the i2c address of the slave controller
>
> This change breaks ABI.
>
> Instead of modifying the definition of the existing compatible value, I
> think you should introduce a new compatible value to describe the
> external NVEC chip.

I changed compatible value to nvec-slave in v2.
> > diff --git a/arch/arm/boot/dts/tegra20-paz00.dts
> > b/arch/arm/boot/dts/tegra20-paz00.dts
>
> > -    nvec@7000c500 {
> > -        compatible = "nvidia,nvec";
> > -        reg = <0x7000c500 0x100>;
> > -        interrupts = <GIC_SPI 92 IRQ_TYPE_LEVEL_HIGH>;
> > -        #address-cells = <1>;
> > -        #size-cells = <0>;
> > +    i2c@7000c500 {
> > +        status = "okay";
> >           clock-frequency = <80000>;
> > -        request-gpios = <&gpio TEGRA_GPIO(V, 2) GPIO_ACTIVE_HIGH>;
> > -        slave-addr = <138>;
> > -        clocks = <&tegra_car TEGRA20_CLK_I2C3>,
> > -                 <&tegra_car TEGRA20_CLK_PLL_P_OUT3>;
> > -        clock-names = "div-clk", "fast-clk";
> > -        resets = <&tegra_car 67>;
> > -        reset-names = "i2c";
> > +
> > +        nvec: nvec@45 {
>
> This doesn't feel correct. There's nothing here to indicate that this
> child device is a slave that is implemented by the host SoC rather than
> something external attached to the I2C bus.
>
> Perhaps you can get away with this, since the driver for nvidia,nvec
> only calls I2C APIs suitable for internal slaves rather than external
> slaves? Even so though, I think the distinction needs to be clearly
> marked in the DT so that any generic code outside the NVEC driver that
> parses the DT can determine the difference.
>
> I would recommend the I2C controller having #address-cells=<2> with cell
> 0 being 0==master,1==slave, cell 1 being the I2C address. The I2C driver
> would need to support #address-cells=<1> for backwards-compatibility.
Driver (nvec in this case) can decide what mode should it use according 
to compatible value. Is it not enough ?

> > +            compatible = "nvidia,nvec";
> > +            request-gpios = <&gpio TEGRA_GPIO(V, 2)
> > +                GPIO_ACTIVE_HIGH>;
> > +            reg = <0x45>;
>
> The order is typically compatible, reg, other properties.

Ok, thanks.
> > +        };
> >       };

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/