Re: [PATCH 3/4 v3][RFC] arm64: renesas: Add initial r8a7795 SoC support

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Laurent,

On Wed, Aug 19, 2015 at 11:29 PM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>> > Also, while you're thinking about the perfect clock binding, please do
>> > consider dropping clock-output-names if you can. Specifying clock-names
>> > alongside the clocks property inside of the consumer node is a bit more
>> > elegant in my opinion. This is also a bit easier if you think about
>> > expressing your clock data with C inside of your provider driver.
>>
>> Makes sense. I don't think anything relies on the "clock-output-names"
>> ... currently.
>>
>> I was going to use it for identifying the GIC clock, though:
>>
>> --- a/drivers/clk/shmobile/clk-mstp.c
>> +++ b/drivers/clk/shmobile/clk-mstp.c
>> @@ -144,6 +144,9 @@ cpg_mstp_clock_register(const char *name, const char
>> *paren init.name = name;
>>         init.ops = &cpg_mstp_clock_ops;
>>         init.flags = CLK_IS_BASIC | CLK_SET_RATE_PARENT;
>> +       /* INTC-SYS is the module clock of the GIC, and must not be disabled
>> */
>> +       if (!strcmp(name, "intc-sys"))
>> +               init.flags |= CLK_ENABLE_HAND_OFF;
>>         init.parent_names = &parent_name;
>>         init.num_parents = 1;
>>
>> (FTR, on R-Car Gen3 the clock is called "intc-ap", not "intc-sys", doh...).
>>
>> This does put some reliance on (undocumented) naming in DT, though, so not
>> having the "clock-output-names" would solve that.
>
> Using the clock name is indeed very messy, let's avoid that.
>
>> However, while "intc-sys"/"intc-ap" (if existent) is always MSTP408, MSTP408
>> is used for other modules on R-Car Gen1 and most older SoCs. so it would
>> complicate the driver code.
>
> How about setting the flag based on information provided in DT ?

Like scanning DT for the GIC, and looking for its clock?

I don't want to add an explicit flag in DT, as it's not a hardware property,
but a deficiency of the current GIC driver/subsystem.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds