Messages in this thread | | | Date | Mon, 1 Mar 2021 15:06:08 +0100 | From | Wilken Gottwalt <> | Subject | Re: [PATCH v6 2/2] hwspinlock: add sun6i hardware spinlock support |
| |
On Mon, 1 Mar 2021 14:13:05 +0100 Maxime Ripard <mripard@kernel.org> wrote:
> On Sat, Feb 27, 2021 at 02:03:54PM +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@posteo.net>
Nope, I had to replace the devm_hwspin_lock_register function by the hwspin_lock_register function because like Bjorn pointed out that it can fail and needs to handled correctly. And having a devm_* function does not play well with the non-devm clock/reset functions and winding back if an error occurs. It also messes with the call order in the remove function. So I went back to the classic way where I have full control over the call order.
> Didn't I review this one already? > Maxime
| |