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SubjectRe: [PATCH] gpio: gpio-mockup: Fix usage of new GPIO_LINE_DIRECTION
On Tue, Dec 10, 2019 at 03:11:12PM +0100, Bartosz Golaszewski wrote:
> wt., 10 gru 2019 o 03:15 Kent Gibson <warthog618@gmail.com> napisał(a):
> >
> > Restore the external behavior of gpio-mockup to what it was prior to the
> > change to using GPIO_LINE_DIRECTION.
> >
> > Signed-off-by: Kent Gibson <warthog618@gmail.com>
> > ---
> >
> > Fix a regression introduced in v5.5-rc1.
> >
> > The change to GPIO_LINE_DIRECTION reversed the polarity of the
> > dir field within gpio-mockup.c, but overlooked inverting the value on
> > initialization and when returned by gpio_mockup_get_direction.
> > The latter is a bug.
> > The former is a problem for tests which assume initial conditions,
> > specifically the mockup used to initialize chips with all lines as inputs.
> > That superficially appeared to be the case after the previous patch due
> > to the bug in gpio_mockup_get_direction.
> >
> > drivers/gpio/gpio-mockup.c | 7 +++++--
> > 1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
> > index 56d647a30e3e..c4fdc192ea4e 100644
> > --- a/drivers/gpio/gpio-mockup.c
> > +++ b/drivers/gpio/gpio-mockup.c
> > @@ -226,7 +226,7 @@ static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
> > int direction;
> >
> > mutex_lock(&chip->lock);
> > - direction = !chip->lines[offset].dir;
> > + direction = chip->lines[offset].dir;
> > mutex_unlock(&chip->lock);
> >
> > return direction;
> > @@ -395,7 +395,7 @@ static int gpio_mockup_probe(struct platform_device *pdev)
> > struct gpio_chip *gc;
> > struct device *dev;
> > const char *name;
> > - int rv, base;
> > + int rv, base, i;
> > u16 ngpio;
> >
> > dev = &pdev->dev;
> > @@ -447,6 +447,9 @@ static int gpio_mockup_probe(struct platform_device *pdev)
> > if (!chip->lines)
> > return -ENOMEM;
> >
> > + for (i = 0; i < gc->ngpio; i++)
> > + chip->lines[i].dir = GPIO_LINE_DIRECTION_IN;
> > +
> > if (device_property_read_bool(dev, "named-gpio-lines")) {
> > rv = gpio_mockup_name_lines(dev, chip);
> > if (rv)
> > --
> > 2.24.0
> >
>
> Hi Kent,
>
> I was applying and testing your libgpiod series and noticed that the
> gpio-tools tests fail after applying patches 16 & 17 (with linux
> v5.5-rc1). Is this fix related to this?
>

I don't think so. I've only been able to trip this problem with a
couple of corner cases in my Go uapi test suite.
I have been unable to reproduce it with the tools as it requires
multiple requests with the same chip fd, including an as-is, to trip.

And running the libgpiod tests against v5.5-rc1 works for me.
Can you provide more details as to the errors you are seeing?

Btw, I was writing tests for your LINEINFO_WATCH patch v2, which I was
applying to v5.5-rc1, when I ran across this. That works ok if I
__packed the changed struct.
And I can confirm that patch v2 doesn't isolate watches on different
chip fds.

Kent.

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