Re: [PATCH v4 5/5] [RFC] clk: shmobile: r8a7795: Add new CPG/MSSR driver

[Michael Turquette <mturquette@baylibre.com>]

Quoting Geert Uytterhoeven (2015-10-20 05:31:12)
> Hi Mike,
> 
> On Tue, Oct 20, 2015 at 2:24 PM, Michael Turquette
> <mturquette@baylibre.com> wrote:
> > Quoting Geert Uytterhoeven (2015-10-16 05:49:20)
> >> +static void __init r8a7795_cpg_mssr_init(struct device_node *np)
> >> +{
> >> +       struct regmap *regmap;
> >> +       u32 reg, cpg_mode;
> >> +
> >> +       regmap = syscon_regmap_lookup_by_phandle(np, "renesas,modemr");
> >> +       if (IS_ERR(regmap) ||
> >> +           of_property_read_u32_index(np, "renesas,modemr", 1, &reg) ||
> >> +           regmap_read(regmap, reg, &cpg_mode)) {
> >> +               pr_err("%s: failed to parse renesas,modemr\n", np->full_name);
> >> +               return;
> >> +       }
> >> +
> >> +       cpg_pll_config = &cpg_pll_configs[CPG_PLL_CONFIG_INDEX(cpg_mode)];
> >> +       if (!cpg_pll_config->extal_div) {
> >> +               pr_err("%s: Prohibited setting (cpg_mode=0x%x)\n",
> >> +                      __func__, cpg_mode);
> >> +               return;
> >> +       }
> >> +
> >> +       cpg_mssr_probe(np, &r8a7795_cpg_mssr_info);
> >> +}
> >> +CLK_OF_DECLARE(r8a7795_cpg_mssr, "renesas,r8a7795-cpg-mssr",
> >> +              r8a7795_cpg_mssr_init);
> >
> > Is CLK_OF_DECLARE needed? Is it possible to make this a real
> > platform_driver à la drivers/clk/qcom/gcc-apq8084.c?
> 
> I tried making it a real platform driver, but it failed: devices that are
> part of the Clock Domain failed to get their clock (error -2, IIRC, which is
> -ENOENT), and thus couldn't be instantiated.
> I didn't look deeper at that time.
> 
> [... reading code ...]
> 
> Aha, this may be caused by __of_clk_get_from_provider() returning
> hardcoded -ENOENT instead of propagating the error returned by
> __clk_create_clk()?

Well the only other error thrown by __clk_create_clk is -ENOMEM, so I'm
not sure how that would help things.

The bindings should go in for 4.4, but if the driver is slated for 4.5
then can you investigate this some more? Stephen and I are on a mission
to have _real_ clk drivers.

Regards,
Mike

> 
> 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