Messages in this thread | | | Date | Wed, 8 Mar 2023 15:06:18 +0200 | From | Andy Shevchenko <> | Subject | Re: [PATCH v4 3/3] gpio: ws16c48: Migrate to the regmap API |
| |
On Tue, Mar 07, 2023 at 09:51:26PM -0500, William Breathitt Gray wrote: > On Mon, Mar 06, 2023 at 04:20:03PM +0200, Andy Shevchenko wrote: > > On Mon, Mar 06, 2023 at 07:59:53AM -0500, William Breathitt Gray wrote:
...
> > > - raw_spinlock_t lock; > > > + spinlock_t lock; > > > > This is a regression. > > That said, do we need a support of raw spin locks in the regmap IRQ? > > So this code has a similar need as the gpio-pcie-idio-24 patch: guard > registers between handle_mask_sync() and set_type_config(); however, now > we also need to protect registers in regmap_irq_thread(). We can't use a > mutex here because regmap_irq_thread() is executed in an interrupt > context so we cannot sleep. > > This might be a mistake in my understanding: I chose spinlock_t here > because I believed it to map out to a raw_spinlock_t anyway underneath, > whereas on RT kernels it would map out to whatever the equivalent is. I > suspect this is not actually the case. Would using raw_spinlock_t > explicitly be the correct way to go for this particular case?
You may read the commit message of the 27d9098cff6e ("pinctrl: intel: Use raw_spinlock for locking"). TL;DR: this is only affects IRQ chips, so if your GPIO controller is _not_ an IRQ chip, you are fine.
WRT the other driver, can_sleep may reduce scope of the use of GPIOs and even make a regression if any consumer don't want that behaviour and currently works.
> > > + u8 irq_mask[WS16C48_NUM_IRQS / WS16C48_NGPIO_PER_REG]; > > > > Can this be a bitmap? Or is it too over engineered with it? > > I also considered a bitmap at first, but I believe it adds an > unnecessary abstraction in this particular case: irq_mask is just a > buffer to hold the previous mask_buf state to check if it's changed when > ws16c48_handle_mask_sync() is called. Since all we do with it is save > the mask_buf directly, using the bitmap API seems like overkill.
Thanks for elaboration!
-- With Best Regards, Andy Shevchenko
| |