linux-kernel - Re: [PATCH v2 2/2] clk: rockchip: rk3288: Handle clock tree for rk3288w

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Date:   Thu, 2 Apr 2020 08:35:05 +0200
From:   Mylene Josserand <mylene.josserand@...labora.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Heiko Stuebner <heiko@...ech.de>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        Collabora Kernel ML <kernel@...labora.com>,
        kever.yang@...k-chips.com
Subject: Re: [PATCH v2 2/2] clk: rockchip: rk3288: Handle clock tree for
 rk3288w

Hi Geert,

On 4/1/20 6:56 PM, Geert Uytterhoeven wrote:
> Hi Mylène,
> 
> On Wed, Apr 1, 2020 at 5:35 PM Mylène Josserand
> <mylene.josserand@...labora.com> wrote:
>> The revision rk3288w has a different clock tree about
>> "hclk_vio" clock, according to the BSP kernel code.
>>
>> This patch handles this difference by detecting which SOC it is
>> and creating the div accordingly. Because we are using
>> soc_device_match function, we need to delay the registration
>> of this clock later than others to have time to get SoC revision.
>>
>> Otherwise, because of CLK_OF_DECLARE uses, clock tree will be
>> created too soon to have time to detect SoC's revision.
>>
>> Signed-off-by: Mylène Josserand <mylene.josserand@...labora.com>
> 
> Thanks for your patch!

Thanks for your review!

> 
>> --- a/drivers/clk/rockchip/clk-rk3288.c
>> +++ b/drivers/clk/rockchip/clk-rk3288.c
>> @@ -914,10 +923,15 @@ static struct syscore_ops rk3288_clk_syscore_ops = {
>>          .resume = rk3288_clk_resume,
>>   };
>>
>> +static const struct soc_device_attribute rk3288w[] = {
>> +       { .soc_id = "RK32xx", .revision = "RK3288w" },
>> +       { /* sentinel */ }
>> +};
>> +
>> +static struct rockchip_clk_provider *ctx;
>> +
>>   static void __init rk3288_clk_init(struct device_node *np)
>>   {
>> -       struct rockchip_clk_provider *ctx;
>> -
>>          rk3288_cru_base = of_iomap(np, 0);
>>          if (!rk3288_cru_base) {
>>                  pr_err("%s: could not map cru region\n", __func__);
>> @@ -955,3 +969,17 @@ static void __init rk3288_clk_init(struct device_node *np)
>>          rockchip_clk_of_add_provider(np, ctx);
>>   }
>>   CLK_OF_DECLARE(rk3288_cru, "rockchip,rk3288-cru", rk3288_clk_init);
>> +
>> +static int __init rk3288_hclkvio_register(void)
>> +{
> 
> This function will always be called, even when running a (multi-platform)
> kernel on a non-rk3288 platform.  So you need some protection against
> that.

erg, good point, I didn't think about that.

> 
>> +       /* Check for the rk3288w revision as clock tree is different */
>> +       if (soc_device_match(rk3288w))
>> +               rockchip_clk_register_branches(ctx, rk3288w_hclkvio_branch,
>> +                                              ARRAY_SIZE(rk3288w_hclkvio_branch));
>> +       else
>> +               rockchip_clk_register_branches(ctx, rk3288_hclkvio_branch,
>> +                                              ARRAY_SIZE(rk3288_hclkvio_branch));
> 
> Note that soc_device_match() returns a struct soc_device_attribute
> pointer.  If you would store the rockchip_clk_branch array pointer and
> size in rk3288w[...].data (i.e. a pointer to a struct containing that
> info), for both the r83288w and normal rk3288 variants, you could
> simplify this to:
> 
>      attr = soc_device_match(rk3288w);
>      if (attr) {
>              struct rk3288_branch_array *p = attr->data;
>              rockchip_clk_register_branches(ctx, p->branches, p->len);
>      }
> 
> That would handle the not-running-on-rk3288 issue as well.

Nice, thank you for the explanation and the code, very useful :)

Best regards,

Mylène