linux-kernel - Re: [PATCH 1/2] regmap: Add hardware spinlock support

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Message-ID: <20171031103830.qdtudo2uwsc2ssp3@sirena.co.uk>
Date:   Tue, 31 Oct 2017 10:38:30 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     gregkh@...uxfoundation.org, lee.jones@...aro.org, arnd@...db.de,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] regmap: Add hardware spinlock support

On Tue, Oct 31, 2017 at 02:35:55PM +0800, Baolin Wang wrote:

This looks mostly good, a few small things:

> +static void regmap_lock_hwlock(void *__map)
> +{
> +	struct regmap *map = __map;
> +	int ret;
> +
> +	if (map->hwlock_timeout)
> +		ret = hwspin_lock_timeout(map->hwlock, map->hwlock_timeout);
> +	else
> +		ret = hwspin_trylock(map->hwlock);
> +
> +	if (ret)
> +		dev_err(map->dev, "Failed to get hwlock %d\n", ret);
> +}

Given that we have no error handling path on the locks should we be
supporting timeout mode at all?  Otherwise we should probably add a
set of error handling paths whenever we take the lock...

> +		if (config->hwlock_mode == HWLOCK_IRQSTATE) {
> +			map->lock = regmap_lock_hwlock_irqsave;
> +			map->unlock = regmap_unlock_hwlock_irqrestore;
> +		} else if (config->hwlock_mode == HWLOCK_IRQ) {
> +			map->lock = regmap_lock_hwlock_irq;
> +			map->unlock = regmap_unlock_hwlock_irq;
> +		} else {
> +			map->lock = regmap_lock_hwlock;
> +			map->unlock = regmap_unlock_hwlock;
> +		}

This should be a switch statement.

> --- a/include/linux/regmap.h
> +++ b/include/linux/regmap.h
> @@ -19,6 +19,7 @@
>  #include <linux/err.h>
>  #include <linux/bug.h>
>  #include <linux/lockdep.h>
> +#include <linux/hwspinlock.h>

We don't actually use hwspinlock.h in the header (the config options are
all just unsigned ints) so this could be moved to regmap.c with a
forward declaration of the struct in internal.h.  That way we don't
force a rebuild of every regmap user when hwspinlock changes.

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