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

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Date:   Tue, 31 Oct 2017 19:47:57 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        Lee Jones <lee.jones@...aro.org>,
        Arnd Bergmann <arnd@...db.de>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] regmap: Add hardware spinlock support

On 31 October 2017 at 19:37, Mark Brown <broonie@...nel.org> wrote:
> On Tue, Oct 31, 2017 at 07:31:57PM +0800, Baolin Wang wrote:
>> On 31 October 2017 at 18:38, Mark Brown <broonie@...nel.org> wrote:
>
>> > 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...
>
>> It will be more helpful to use the timeout to try more times to get
>> the hwlock, and we usually do not use hwspin_trylock_xxx(), so we can
>> remove hwspin_trylock_xxx() support and set timeout as MAX value as
>> default to avoid adding 'hwlock_timeout' config,
>> is this OK for you?
>
> I *think* so - but let's see the code.  It might make sense to do two
> patches, one with the base hwspinlock support then another adding the
> timeout functionality.  That way if there's any problem we can still
> merge the non-timeout code and there's less to review next time.

What I mean is we only introduce the timeout functions, since we do
not want to get the hwlocks failed to avoid error handling path:

static void regmap_lock_hwlock(void *__map)
{
    struct regmap *map = __map;

    hwspin_lock_timeout(map->hwlock, ~0U);
}

static void regmap_lock_hwlock_irq(void *__map)
{
    struct regmap *map = __map;

    hwspin_lock_timeout_irq(map->hwlock, ~0U);
}

static void regmap_lock_hwlock_irqsave(void *__map)
{
    struct regmap *map = __map;

    hwspin_lock_timeout_irqsave(map->hwlock, ~0U, &map->spinlock_flags);
}

-- 
Baolin.wang
Best Regards