Re: [PATCHv10 00/41] ARM: TI SoC clock DT conversion

[Mike Turquette <mturquette@linaro.org>]

Quoting Tero Kristo (2013-11-26 00:05:41)
> Hi,
> 

Hi Tero,

Thanks for your long suffering patience on this series. The clock
patches look very good to me with exception of a few small comments. Let
me know how I can help with the hierarchal DT stuff since I think that
has been the gating factor for this series for the past few revisions.

> Changes compared to v9:
> - rebased on top of 3.13-rc1
> - modified the low level clk register API to provide SoC specific clk_readl
>   and clk_writel support which can be registered during boot, TI SoC variant
>   uses regmap on low level

Regarding regmap, will that be dropped for V11? I don't care whether it
stays or goes but the approach you took is probably too top-level. Patch
#1 sets clk_reg_ops system-wide which probably isn't right. Different
clock drivers might compete to set those ops and the last one to write
wins.

A better approach is to support regmap ops on a per-clock basis (for
clocks that use the generic implementations like clk-divider and
clk-gate; obviously this is overkill for entirely hardware-specific
clocks). Stephen Boyd's approach is a better solution[1][2] but
unfortunately that approach dumps crap into struct clk_hw which is bad.

Anyways if you decide against regmap for V11 then the whole issue is
avoided.

Regards,
Mike

[1] http://article.gmane.org/gmane.linux.ports.arm.kernel/273742
[2] http://article.gmane.org/gmane.linux.ports.arm.kernel/273744

> - dropped regmap parameter from clock init calls, instead a helper is used
>   for getting regmap index along with the register offset from DT
> - dropped regmap parameter from clock structs, instead platform specific
>   clk_readl / clk_writel are used to parse reg parameter according to
>   platform, for TI SoC:s, this is encoded as:
>   struct clk_omap_reg {
>     u16 offset; /* register offset */
>     u16 index; /* regmap index */
>   }
> - Nishanth's comments to v9 mostly addressed, except for the CLK_OF_DECLARE
>   tweak which I would actually want some feedback upon, basically the problem
>   is I need to return status from the clk init functions so I can see if
>   -EAGAIN is passed, in which case init will be retried later, maybe some of
>   this can be made generic, like converting all the CLK_OF_DECLARE type
>   functions to return status
> 
> Testing done:
> - omap3-beagle : boot + suspend/resume
> - omap3-beagle-xm : boot (thanks to Nishanth)
> - omap4-panda-es : boot + suspend/resume
> - omap5-uevm : boot
> - dra7-evm : boot
> - am335x-bone : boot
> 
> Separate branches available at https://github.com/t-kristo/linux-pm.git
> 
> - full: 3.13-rc1-dt-clks-v10 (should be merged last, contains everything)
> - clk driver only: 3.13-rc1-dt-clks-v10-for-mike
> - DT data only: 3.13-rc1-dt-clks-v10-for-benoit
> 
> -Tero
>