linux-kernel - Re: [PATCH v5 2/2] hwspinlock: add sun6i hardware spinlock support

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Date:   Fri, 8 Jan 2021 09:57:38 +0100
From:   Maxime Ripard <maxime@...no.tech>
To:     Wilken Gottwalt <wilken.gottwalt@...teo.net>
Cc:     linux-kernel@...r.kernel.org, Ohad Ben-Cohen <ohad@...ery.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Baolin Wang <baolin.wang7@...il.com>,
        Rob Herring <robh+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...l.net>
Subject: Re: [PATCH v5 2/2] hwspinlock: add sun6i hardware spinlock support

On Thu, Jan 07, 2021 at 09:43:14AM +0100, Wilken Gottwalt wrote:
> On Wed, 6 Jan 2021 11:15:42 +0100
> Maxime Ripard <maxime@...no.tech> wrote:
> 
> > On Wed, Dec 23, 2020 at 12:35:10PM +0100, Wilken Gottwalt wrote:
> > > Adds the sun6i_hwspinlock driver for the hardware spinlock unit found in
> > > most of the sun6i compatible SoCs.
> > > 
> > > This unit provides at least 32 spinlocks in hardware. The implementation
> > > supports 32, 64, 128 or 256 32bit registers. A lock can be taken by
> > > reading a register and released by writing a 0 to it. This driver
> > > supports all 4 spinlock setups, but for now only the first setup (32
> > > locks) seem to exist in available devices. This spinlock unit is shared
> > > between all ARM cores and the embedded companion core. All of them can
> > > take/release a lock with a single cycle operation. It can be used to
> > > sync access to devices shared by the ARM cores and the companion core.
> > > 
> > > There are two ways to check if a lock is taken. The first way is to read
> > > a lock. If a 0 is returned, the lock was free and is taken now. If an 1
> > > is returned, the caller has to try again. Which means the lock is taken.
> > > The second way is to read a 32bit wide status register where every bit
> > > represents one of the 32 first locks. According to the datasheets this
> > > status register supports only the 32 first locks. This is the reason the
> > > first way (lock read/write) approach is used to be able to cover all 256
> > > locks in future devices. The driver also reports the amount of supported
> > > locks via debugfs.
> > > 
> > > Signed-off-by: Wilken Gottwalt <wilken.gottwalt@...teo.net>
> > 
> > Reviewed-by: Maxime Ripard <mripard@...nel.org>
> 
> Does it mean the driver is okay and I only need to fix the bindings
> documentation? If so, would you prefer an updated patch set or only the
> documentation patch in a new version?

It means I'm fine with the driver patch but the binding require a new
version. Send a new version of the series with my reviewed-by added to
the driver commit

Maxime