Messages in this thread | | | Date | Thu, 1 May 2014 00:17:39 +0200 | Subject | Re: [PATCH/RFC 0/4] of: Register clocks for Runtime PM with PM core | From | Geert Uytterhoeven <> |
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Hi Laurent,
On Wed, Apr 30, 2014 at 11:29 PM, Laurent Pinchart <laurent.pinchart@ideasonboard.com> wrote: > On Thursday 24 April 2014 12:13:19 Geert Uytterhoeven wrote: >> On SoCs like ARM/SH-mobile, gate clocks are available for modules, allowing >> Runtime PM for a device controlled by a gate clock. >> >> On legacy shmobile kernels, this is handled by the PM runtime code in >> drivers/sh/pm_runtime.c, which installs a clock notifier for the platform >> bus, registering the "NULL" clock of each platform device with the PM core. >> This approach is also used on davinci, keystone, and omap1. > > This requires the device to have the MSTP clock defined as the first clock in > its DT node. I'm not against that, but the requirement should be clearly > documented, and we need to check existing DT bindings to make sure they comply > with that.
Being the first clock is only required for the "NULL" clock. And that is only done for legacy shmobile kernels, not for multi-platform.
In this patch series, the clock would be chosen based on the presence of the CLK_RUNTIME_PM flag, to be set by the clock driver. I.e. DT is not involved directly (for a change... why does everybody think the whole world revolves around DT these days ? :-)
> I'd like to also take this as an opportunity to discuss how we should name > clocks in DT bindings for Renesas devices. Most devices have a single MSTP > clock, in which case we don't specify a name. Other devices need several > clocks. Names for the non-MSTP clocks will obviously be device-dependent, but > how should the MSTP clock be called in that time ? Should it have an empty > name (a "" string in DT) ? Should it have a standard name ? Maybe "fck" for > "functional clock" ?
Empty names should not be used if there can be multiple clocks, right?
Grepping in arch/*/boot/dts/, "fck" seems to be popular (only) for TI SoCs.
Stadardizing across SoCs and architectures would be nice, though.
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
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