Re: [PATCH 09/33] ARM: ux500: Supply the I2C clocks lookup to the DBX500 DT

[Mark Rutland <mark.rutland@arm.com>]

On Fri, Aug 23, 2013 at 08:56:07AM +0100, Lee Jones wrote:
> I had a short chat with Rob last night about this. I'm going to loop
> him in to the conversation, as he wrote the binding.
> 
> > > When most of the other clocks that we deal with are being requested,
> > > they rely on being index zero:
> > > 
> > >   drivers/i2c/busses/i2c-nomadik.c: dev->clk = clk_get(&adev->dev, NULL);
> > 
> > Look at drivers/clk/clkdev.c, there's some fuzzy matching
> > involved when you pass NULL as connection id.
> 
> Yes, I've been looking at that. This is why it works currently. I
> think I need to change all of the drivers to specify which clock they
> want. At the moment that 'fuzzy matching' is what's saving us. If
> anyone were to change our DTS file to match what the binding says,
> then it would cease to work. I'm guessing this is the same for all
> other DTS files too:

I think if anything, the binding document(s) should be updated to
describe that apb_pclk is referred to by name, and the names of the
other clocks should be described in the specific device bindings. We can
then modify the drivers which grab clock 0 to explicitly grab the first
clock by name, and backwards compatibility should not be broken.

I don't believe any other OS has implemented the common clock bindings,
and we've never supported the binding as described. Let's correct the
de-facto standard into a standard by decree.

Thanks,
Mark.

> 
> arch/arm/boot/dts/imx23.dtsi:                clock-names = "uart", "apb_pclk";
> arch/arm/boot/dts/imx28.dtsi:                clock-names = "uart", "apb_pclk";
> arch/arm/boot/dts/nspire-cx.dts:             clock-names = "uart_clk", "apb_pclk";
> arch/arm/boot/dts/ste-nomadik-stn8815.dtsi:  clock-names = "timclk", "apb_pclk";
> arch/arm/boot/dts/ste-nomadik-stn8815.dtsi:  clock-names = "timclk", "apb_pclk";
> arch/arm/boot/dts/ste-nomadik-stn8815.dtsi:  clock-names = "uartclk", "apb_pclk";
> arch/arm/boot/dts/ste-nomadik-stn8815.dtsi:  clock-names = "uartclk", "apb_pclk";
> arch/arm/boot/dts/ste-nomadik-stn8815.dtsi:  clock-names = "uartclk", "apb_pclk";
> arch/arm/boot/dts/ste-nomadik-stn8815.dtsi:  clock-names = "rng", "apb_pclk";
> arch/arm/boot/dts/ste-nomadik-stn8815.dtsi:  clock-names = "mclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m-rs1.dtsi:     clock-names = "refclk", "timclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m-rs1.dtsi:     clock-names = "mclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m-rs1.dtsi:     clock-names = "KMIREFCLK", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m-rs1.dtsi:     clock-names = "KMIREFCLK", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m-rs1.dtsi:     clock-names = "uartclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m-rs1.dtsi:     clock-names = "uartclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m-rs1.dtsi:     clock-names = "uartclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m-rs1.dtsi:     clock-names = "uartclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m-rs1.dtsi:     clock-names = "wdogclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m-rs1.dtsi:     clock-names = "timclken1", "timclken2", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m-rs1.dtsi:     clock-names = "timclken1", "timclken2", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m-rs1.dtsi:     clock-names = "clcdclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m.dtsi:         clock-names = "refclk", "timclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m.dtsi:         clock-names = "mclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m.dtsi:         clock-names = "KMIREFCLK", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m.dtsi:         clock-names = "KMIREFCLK", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m.dtsi:         clock-names = "uartclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m.dtsi:         clock-names = "uartclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m.dtsi:         clock-names = "uartclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m.dtsi:         clock-names = "uartclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m.dtsi:         clock-names = "wdogclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m.dtsi:         clock-names = "timclken1", "timclken2", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m.dtsi:         clock-names = "timclken1", "timclken2", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2m.dtsi:         clock-names = "clcdclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts:  clock-names = "wdogclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2p-ca9.dts:      clock-names = "clcdclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2p-ca9.dts:      clock-names = "timclk", "apb_pclk";
> arch/arm/boot/dts/vexpress-v2p-ca9.dts:      clock-names = "wdogclk", "apb_pclk";
> 
> -- 
> Lee Jones
> Linaro ST-Ericsson Landing Team Lead
> Linaro.org │ Open source software for ARM SoCs
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