Re: [PATCH v2 04/11] gpiolib: Clear the gpio_device's fwnode initialized flag before adding

Saravana Kannan
2023-02-04T22:32:52Z

On Tue, Jan 31, 2023 at 2:13 AM Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> On Mon, Jan 30, 2023 at 08:01:17PM -0800, Saravana Kannan wrote:
> > On Mon, Jan 30, 2023 at 7:14 AM Andy Shevchenko
> > <andriy.shevchenko@linux.intel.com> wrote:
> > >
> > > On Mon, Jan 30, 2023 at 02:31:53PM +0000, Sudeep Holla wrote:
> > > > On Thu, Jan 26, 2023 at 04:11:31PM -0800, Saravana Kannan wrote:
> > > > > Registering an irqdomain sets the flag for the fwnode. But having the
> > > > > flag set when a device is added is interpreted by fw_devlink to mean the
> > > > > device has already been initialized and will never probe. This prevents
> > > > > fw_devlink from creating device links with the gpio_device as a
> > > > > supplier. So, clear the flag before adding the device.
> > >
> > > ...
> > >
> > > > > + /*
> > > > > + * If fwnode doesn't belong to another device, it's safe to clear its
> > > > > + * initialized flag.
> > > > > + */
> > > > > + if (!gdev->dev.fwnode->dev)
> > > > > + fwnode_dev_initialized(gdev->dev.fwnode, false);
> > > >
> > > > This is the one causing the kernel crash during the boot on FVP which
> > > > Naresh has reported. Just reverted this and was able to boot, confirming
> > > > the issue with this patch.
> > >
> > > I'm wondering if
> > >
> > > if (!dev_fwnode(&gdev->dev)->dev)
> > > fwnode_dev_initialized(&dev_fwnode(gdev->dev), false);
> > >
> > > works.
> >
> > No, that won't help. The problem was that with arm32, we have gpio
> > devices created without any of_node or fwnode. So I can't assume
> > fwnode will always be present.
> >
>
> Correct, and this one is not even arm32. But it is just reusing a driver
> that needs to be supported even on arm32.
>
> Not sure on how to proceed. As a simple way to check, I added a NULL check
> for fwnode building on top of Andy's suggestion[1]. That works.
>
> Also the driver in question on arm64 FVP model is drivers/mfd/vexpress-sysreg.c
> mfd_add_device() in drivers/mfd/mfd-core.c allows addition of devices without
> of_node/fwnode. I am sure returning error like[2] will break many platforms
> but I just wanted to confirm the root cause and [2] fixes the boot without
> NULL check for fwnode in gpiochip_setup_dev().
>
> Hope this helps.

Thanks for debugging it for me Sudeep. Incorporated into my v3.

-Saravana

>
> --
> Regards,
> Sudeep
>
> [1]
>
> -->8
> diff --git i/drivers/gpio/gpiolib.c w/drivers/gpio/gpiolib.c
> index b23140c6485f..e162f13aa2c9 100644
> --- i/drivers/gpio/gpiolib.c
> +++ w/drivers/gpio/gpiolib.c
> @@ -577,13 +577,15 @@ static void gpiodevice_release(struct device *dev)
> static int gpiochip_setup_dev(struct gpio_device *gdev)
> {
> int ret;
> + struct fwnode_handle *fwnode = dev_fwnode(&gdev->dev);
>
> /*
> * If fwnode doesn't belong to another device, it's safe to clear its
> * initialized flag.
> */
> - if (!gdev->dev.fwnode->dev)
> - fwnode_dev_initialized(gdev->dev.fwnode, false);
> + if (fwnode && !fwnode->dev)
> + fwnode_dev_initialized(fwnode, false);
> +
> ret = gcdev_register(gdev, gpio_devt);
> if (ret)
> return ret;
>
> [2]
>
> -->8
>
> diff --git i/drivers/mfd/mfd-core.c w/drivers/mfd/mfd-core.c
> index 16d1861e9682..3b2c4b0e9a2a 100644
> --- i/drivers/mfd/mfd-core.c
> +++ w/drivers/mfd/mfd-core.c
> @@ -231,9 +231,11 @@ static int mfd_add_device(struct device *parent, int id,
> }
> }
>
> - if (!pdev->dev.of_node)
> + if (!pdev->dev.of_node) {
> pr_warn("%s: Failed to locate of_node [id: %d]\n",
> cell->name, platform_id);
> + goto fail_alias;
> + }
> }
>
> mfd_acpi_add_device(cell, pdev);
>