On May 13 2024, Andy Shevchenko wrote:
> On Mon, May 13, 2024 at 03:59:01PM +0800, Devyn Liu wrote:
> > Previous patch modified the standard used by acpi_gpiochip_find()
> > to match device nodes. Using the device node set in gc->gpiodev->d-
> > ev instead of gc->parent.
> >
> > However, there is a situation in gpio-dwapb where the GPIO device
> > driver will set gc->fwnode for each port corresponding to a child
> > node under a GPIO device, so gc->gpiodev->dev will be assigned the
> > value of each child node in gpiochip_add_data().
> >
> > gpio-dwapb.c:
> > 128,31 static int dwapb_gpio_add_port(struct dwapb_gpio *gpio,
> > struct dwapb_port_property *pp,
> > unsigned int offs);
> > port->gc.fwnode = pp->fwnode;
> >
> > 693,39 static int dwapb_gpio_probe;
> > err = dwapb_gpio_add_port(gpio, &pdata->properties[i], i);
> >
> > When other drivers request GPIO pin resources through the GPIO device
> > node provided by ACPI (corresponding to the parent node), the change
> > of the matching object to gc->gpiodev->dev in acpi_gpiochip_find()
> > only allows finding the value of each port (child node), resulting
> > in a failed request.
> >
> > Reapply the condition of using gc->parent for match in acpi_gpio-
> > chip_find() in the code can compatible with the problem of gpio-dwapb,
> > and will not affect the two cases mentioned in the patch:
> > 1. There is no setting for gc->fwnode.
> > 2. The case that depends on using gc->fwnode for match.
>
> Thanks for the report, analysis, and patch.
>
> ...
>
> > static int acpi_gpiochip_find(struct gpio_chip *gc, const void *data)
> > {
> > - return device_match_acpi_handle(&gc->gpiodev->dev, data);
> > + return device_match_acpi_handle(&gc->gpiodev->dev, data) ||
> > + (gc->parent && device_match_acpi_handle(gc->parent, data));
> > }
The original patch (from Devyn) is:
Tested-by: Benjamin Tissoires <bentiss@xxxxxxxxxx>
For reference, a successful run can be seen at:
https://gitlab.freedesktop.org/bentiss/hid/-/jobs/58661693
>
> I'm wondering if the below approach will work for all:
>
> static int acpi_gpiochip_find(struct gpio_chip *gc, const void *data)
> {
> struct device *dev = acpi_get_first_physical_node(ACPI_COMPANION(&gc->gpiodev->dev));
>
> return device_match_acpi_handle(dev, data);
> }
Looks like I get a bad dev pointer in this situation:
https://gitlab.freedesktop.org/bentiss/hid/-/jobs/58662689#L704
Not sure if this is because the not-yet-upstream patches I have in
hid-cp2112 are doing something wrong or if there is a good reason for
it...
The patch that adds fwnode to hid-cp2112 are:
https://gitlab.freedesktop.org/bentiss/gitlab-kernel-ci/-/blob/master/VM/0002-HID-usbhid-Share-USB-device-firmware-node-with-child.patch
https://gitlab.freedesktop.org/bentiss/gitlab-kernel-ci/-/blob/master/VM/0003-HID-cp2112-Fwnode-Support.patch
both of those patches are applied before compilation in the CI run from
above.
>
> Cc'ing to Benjamin for testing and commenting.
TL;DR: initial patch is fine, yours will probably need a check on the
dev return value, so not sure if we gain a lot...
Cheers,
Benjamin
