Re: [PATCH v2 3/9] clk: at91: pmc: Support backup for programmable clocks

[Romain Izard <romain.izard.pro@gmail.com>]

2017-09-22 12:31 GMT+02:00 Nicolas Ferre <nicolas.ferre@microchip.com>:
> On 15/09/2017 at 16:04, Romain Izard wrote:
>> From: Romain Izard <romain.izard@mobile-devices.fr>
>>
>> When an AT91 programmable clock is declared in the device tree, register
>> it into the Power Management Controller driver. On entering suspend mode,
>> the driver saves and restores the Programmable Clock registers to support
>> the backup mode for these clocks.
>>
>> Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
>
> Romain,
>
> Some nitpicking and one comment. But on the overall patch, here is my:
> Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
>
> See below:
>
>> ---
>> Changes in v2:
>> * register PCKs on clock startup
>>
>>  drivers/clk/at91/clk-programmable.c |  2 ++
>>  drivers/clk/at91/pmc.c              | 27 +++++++++++++++++++++++++++
>>  drivers/clk/at91/pmc.h              |  2 ++
>>  3 files changed, 31 insertions(+)
>>
>> diff --git a/drivers/clk/at91/clk-programmable.c b/drivers/clk/at91/clk-programmable.c
>> index 85a449cf61e3..0e6aab1252fc 100644
>> --- a/drivers/clk/at91/clk-programmable.c
>> +++ b/drivers/clk/at91/clk-programmable.c
>> @@ -204,6 +204,8 @@ at91_clk_register_programmable(struct regmap *regmap,
>>       if (ret) {
>>               kfree(prog);
>>               hw = ERR_PTR(ret);
>
> Nit: "else" not needed.
>
This is a shared idiom in all the atmel clock drivers, so I prefer to keep
it this way.

>> +     } else {
>> +             pmc_register_pck(id);
>>       }
>>
>>       return hw;
>> diff --git a/drivers/clk/at91/pmc.c b/drivers/clk/at91/pmc.c
>> index 07dc2861ad3f..3910b7537152 100644
>> --- a/drivers/clk/at91/pmc.c
>> +++ b/drivers/clk/at91/pmc.c
>> @@ -22,6 +22,7 @@
>>  #include "pmc.h"
>>
>>  #define PMC_MAX_IDS 128
>> +#define PMC_MAX_PCKS 8
>>
>>  int of_at91_get_clk_range(struct device_node *np, const char *propname,
>>                         struct clk_range *range)
>> @@ -50,6 +51,7 @@ EXPORT_SYMBOL_GPL(of_at91_get_clk_range);
>>  static struct regmap *pmcreg;
>>
>>  static u8 registered_ids[PMC_MAX_IDS];
>> +static u8 registered_pcks[PMC_MAX_PCKS];
>>
>>  static struct
>>  {
>> @@ -66,8 +68,10 @@ static struct
>>       u32 pcr[PMC_MAX_IDS];
>>       u32 audio_pll0;
>>       u32 audio_pll1;
>> +     u32 pckr[PMC_MAX_PCKS];
>>  } pmc_cache;
>>
>> +/* Clock ID 0 is invalid */
>
> (read: so we can use the 0 value as an indicator that this place in the
> table hasn't been filled, so unused)
>
>>  void pmc_register_id(u8 id)
>>  {
>>       int i;
>> @@ -82,6 +86,21 @@ void pmc_register_id(u8 id)
>>       }
>>  }
>>
>> +/* Programmable Clock 0 is valid */
>
> I understand the rationale behind these ^^ two comments, but I would
> like that it's more explicit. Saying that you will store the pck id as
> (id + 1) and that you would have to invert this operation while using
> the stored id.
> Maybe add a comment about this transformation to the struct definition
> as well...
>

I will improve the comments for the next revision.

>
>> +void pmc_register_pck(u8 pck)
>> +{
>> +     int i;
>> +
>> +     for (i = 0; i < PMC_MAX_PCKS; i++) {
>> +             if (registered_pcks[i] == 0) {
>> +                     registered_pcks[i] = pck + 1;
>> +                     break;
>> +             }
>> +             if (registered_pcks[i] == (pck + 1))
>> +                     break;
>> +     }
>> +}
>> +
>>  static int pmc_suspend(void)
>>  {
>>       int i;
>> @@ -103,6 +122,10 @@ static int pmc_suspend(void)
>>               regmap_read(pmcreg, AT91_PMC_PCR,
>>                           &pmc_cache.pcr[registered_ids[i]]);
>>       }
>> +     for (i = 0; registered_pcks[i]; i++) {
>> +             u8 num = registered_pcks[i] - 1;
>
> Nit: declaration are better made at the beginning of the function. This
> lead to a checkpatch warning:
> "WARNING: Missing a blank line after declarations"
>

I'll fix this as well.

>> +             regmap_read(pmcreg, AT91_PMC_PCKR(num), &pmc_cache.pckr[num]);
>> +     }
>>
>>       return 0;
>>  }
>> @@ -143,6 +166,10 @@ static void pmc_resume(void)
>>                            pmc_cache.pcr[registered_ids[i]] |
>>                            AT91_PMC_PCR_CMD);
>>       }
>> +     for (i = 0; registered_pcks[i]; i++) {
>> +             u8 num = registered_pcks[i] - 1;
>
> Ditto
>
>> +             regmap_write(pmcreg, AT91_PMC_PCKR(num), pmc_cache.pckr[num]);
>> +     }
>>
>>       if (pmc_cache.uckr & AT91_PMC_UPLLEN)
>>               mask |= AT91_PMC_LOCKU;
>> diff --git a/drivers/clk/at91/pmc.h b/drivers/clk/at91/pmc.h
>> index 858e8ef7e8db..d22b1fa9ecdc 100644
>> --- a/drivers/clk/at91/pmc.h
>> +++ b/drivers/clk/at91/pmc.h
>> @@ -31,8 +31,10 @@ int of_at91_get_clk_range(struct device_node *np, const char *propname,
>>
>>  #ifdef CONFIG_PM
>>  void pmc_register_id(u8 id);
>> +void pmc_register_pck(u8 pck);
>>  #else
>>  static inline void pmc_register_id(u8 id) {}
>> +static inline void pmc_register_pck(u8 pck) {}
>>  #endif
>>
>>  #endif /* __PMC_H_ */
>>

-- 
Romain Izard