[U-Boot] [PATCH v6 15/20] tegra: fdt: Add function to return peripheral/clock ID

[Simon Glass]

Hi Stephen,

On Tue, Feb 28, 2012 at 10:51 AM, Stephen Warren <swarren at nvidia.com> wrote:
> Simon Glass wrote at Tuesday, February 28, 2012 11:44 AM:
>> On Tue, Feb 28, 2012 at 10:37 AM, Stephen Warren <swarren at nvidia.com> wrote:
>> > Simon Glass wrote at Tuesday, February 28, 2012 10:46 AM:
>> >> On Mon, Feb 27, 2012 at 3:41 PM, Stephen Warren <swarren at nvidia.com> wrote:
>> >> > On 02/27/2012 01:52 PM, Simon Glass wrote:
>> >> >> A common requirement is to find the clock ID for a peripheral. This is the
>> >> >> second cell of the 'clocks' property (the first being the phandle itself).
>> >> >
>> >> >> +int clock_decode_periph_id(const void *blob, int node)
>> >> >
>> >> >> +     valid = clock_periph_id_isvalid(id);
>> >> >
>> >> > clock_periph_id_isvalid() is not the correct function to use here; the
>> >> > code should be checking for invalid IDs in the CAR binding, not invalid
>> >> > IDs in the HW periph ID definition. They're different.
>> >> >
>> >> > Just to be explicit, the function you need here would be:
>> >> >
>> >> > int clkid_to_periphid(int clkid)
>> >> > {
>> >> >    if (clk_id > 95)
>> >> >        return -1;
>> >> >    switch (clk_id) {
>> >> >    case 1:
>> >> >    case 2:
>> >> >    case 7:
>> >> >    case 10:
>> >> >    case 20:
>> >> >    case 30:
>> >> >    case 35:
>> >> >    case 49:
>> >> >    case 56:
>> >> >    case 74:
>> >> >    case 77:
>> >> >    case 78:
>> >> >    case 79:
>> >> >    case 80:
>> >> >    case 81:
>> >> >    case 82:
>> >> >    case 83:
>> >> >    case 91:
>> >> >    case 95:
>> >> >        return -1;
>> >> >    default:
>> >> >        return clkid;
>> >> >    }
>> >> > }
>> >>
>> >> Ick.
>> >>
>> >> Why is 7 in there,
>> >
>> > 7 affects both the UART2 and VFIR clocks/blocks.
>> >
>> >> and did you miss 76?
>> >
>> > No, that's the undocumented "la" clock.
>> >
>> >> Also U-Boot only goes up to 88
>> >> at present so should I change the first test to match?
>> >
>> > No, clocks 89, 90, 92, 93, and 94 are defined in the binding, which
>> > matches the CLK_OUT_ENB registers in the Tegra CAR HW (albeit not the
>> > CLK_RST registers, since there are some differences between the two).
>>
>> For both of your comments, since they aren't used in U-Boot, wouldn't
>> it be more correct to flag these as errors also? We would have to
>> update at least the clock.h header to support them.
>
> It's probably more correct to update the periph_id enum to define all
> the valid values, but either way is fine.

OK - BTW what does 'LA' stand for?

Regards,
Simon

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