On Wed, 2023-12-06 at 16:27 -0600, David Lechner wrote:
> On Tue, Dec 5, 2023 at 11:06 AM Nuno Sa via B4 Relay
> <devnull+nuno.sa.analog.com@xxxxxxxxxx> wrote:
> >
> > From: Nuno Sa <nuno.sa@xxxxxxxxxx>
> >
> > When calling ad9467_set_scale(), multiple calls to ad9467_spi_write()
> > are done which means we need to properly protect the whole operation so
> > we are sure we will be in a sane state if two concurrent calls occur.
>
>
> ad9467_outputmode_set() also has multiple calls to ad9467_spi_write().
> Does it need similar protection?
>
Just called during probe (of the axi-adc driver) before registering the IIO device.
We should not need the lock in there (for now).
> >
> > Fixes: ad6797120238 ("iio: adc: ad9467: add support AD9467 ADC")
> > Signed-off-by: Nuno Sa <nuno.sa@xxxxxxxxxx>
> > ---
> > drivers/iio/adc/ad9467.c | 7 ++++++-
> > 1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/iio/adc/ad9467.c b/drivers/iio/adc/ad9467.c
> > index 0f2dce730a0a..badbef2ce9f8 100644
> > --- a/drivers/iio/adc/ad9467.c
> > +++ b/drivers/iio/adc/ad9467.c
> > @@ -4,8 +4,9 @@
> > *
> > * Copyright 2012-2020 Analog Devices Inc.
> > */
> > -
> > +#include <linux/cleanup.h>
> > #include <linux/module.h>
> > +#include <linux/mutex.h>
> > #include <linux/device.h>
> > #include <linux/kernel.h>
> > #include <linux/slab.h>
> > @@ -121,6 +122,8 @@ struct ad9467_state {
> > unsigned int output_mode;
> >
> > struct gpio_desc *pwrdown_gpio;
> > + /* ensure consistent state obtained on multiple related accesses */
> > + struct mutex lock;
> > };
> >
> > static int ad9467_spi_read(struct spi_device *spi, unsigned int reg)
> > @@ -161,6 +164,7 @@ static int ad9467_reg_access(struct adi_axi_adc_conv *conv,
> > unsigned int reg,
> > int ret;
> >
> > if (readval == NULL) {
> > + guard(mutex)(&st->lock);
> > ret = ad9467_spi_write(spi, reg, writeval);
> > if (ret)
> > return ret;
> > @@ -310,6 +314,7 @@ static int ad9467_set_scale(struct adi_axi_adc_conv *conv,
> > int val, int val2)
> > if (scale_val[0] != val || scale_val[1] != val2)
> > continue;
> >
> > + guard(mutex)(&st->lock);
>
> Why is the guard inside of the for loop instead of outside?
>
> __ad9467_get_scale() called in this loop calls ad9467_spi_read() too,
Hmm, am I missing something? __ad9467_get_scale() is not doing any spi access, is it?
I think you made confusion with the version without underscore...
- Nuno Sá
>
