Re: [PATCH 1/2] leds: bcm6328: improve write and read functions

From: Álvaro Fernández Rojas
Date: Tue Feb 23 2021 - 03:43:08 EST


Hi Pavel,

> El 23 feb 2021, a las 9:34, Pavel Machek <pavel@xxxxxx> escribió:
>
> On Tue 2021-02-23 09:17:31, Álvaro Fernández Rojas wrote:
>> This is proven to work in BMIPS BE/LE and ARM BE/LE, as used in bcm2835-rng
>> and bcmgenet drivers.
>> Both should also be inline functions.
>
>
>
>> -#ifdef CONFIG_CPU_BIG_ENDIAN
>> - iowrite32be(data, reg);
>> -#else
>> - writel(data, reg);
>> -#endif
>> + /* MIPS chips strapped for BE will automagically configure the
>> + * peripheral registers for CPU-native byte order.
>> + */
>
> Bad comment style.

I just wanted to copy the same comment as the one in bcm2835-rng and bcmgenet…
https://github.com/torvalds/linux/blob/3b9cdafb5358eb9f3790de2f728f765fef100731/drivers/char/hw_random/bcm2835-rng.c#L42-L60
https://github.com/torvalds/linux/blob/3b9cdafb5358eb9f3790de2f728f765fef100731/drivers/net/ethernet/broadcom/genet/bcmgenet.c#L71-L88

>
>> + if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
>> + __raw_writel(data, reg);
>> + else
>> + writel_relaxed(data, reg);
>> }
>
> Code does not match comment (still need to do conversion on
> non-MIPS?), and it certainly should not be here (do all mipsen behave
> like that?!), and it really should not be converting to _relaxed at
> the same time.

I think it's because non-MIPS BE exposes that as little endian, but Florian can probably help us with that…

>
> Best regards,
> Pavel
> --
> http://www.livejournal.com/~pavelmachek

Best regards,
Álvaro.