linux-kernel - Re: [PATCH] iio: accel: bmc150: Do not configure IRQ registers if no IRQ connected

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Message-ID: <aE_aL5dGKZeKBu50@smile.fi.intel.com>
Date: Mon, 16 Jun 2025 11:47:43 +0300
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Marek Vasut <marek.vasut@...lbox.org>
Cc: Marek Vasut <marek.vasut+bmc150@...lbox.org>,
	Hans de Goede <hansg@...nel.org>, linux-iio@...r.kernel.org,
	Nuno Sá <nuno.sa@...log.com>,
	Andy Shevchenko <andy@...nel.org>,
	David Lechner <dlechner@...libre.com>,
	Jonathan Cameron <jic23@...nel.org>,
	Julien Stephan <jstephan@...libre.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Salvatore Bonaccorso <carnil@...ian.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: accel: bmc150: Do not configure IRQ registers if no
 IRQ connected

On Fri, Jun 13, 2025 at 07:02:28PM +0200, Marek Vasut wrote:
> On 6/13/25 5:09 PM, Andy Shevchenko wrote:
> > On Fri, Jun 13, 2025 at 02:45:22PM +0200, Marek Vasut wrote:

> > > The BMC150 on Onemix 2S does not have IRQ line described in ACPI tables,
> > > which leads to bmc150_accel_core_probe() being called with irq=0, which
> > > leads to bmc150_accel_interrupts_setup() never being called, which leads
> > > to struct bmc150_accel_data *data ->interrupts[i].info being left unset
> > > to NULL. Later, userspace can indirectly trigger bmc150_accel_set_interrupt()
> > > which depends on struct bmc150_accel_data *data ->interrupts[i].info being
> > > non-NULL, and which triggers NULL pointer dereference. This is triggered
> > > e.g. from iio-sensor-proxy.
> > > 
> > > Fix this by skipping the IRQ register configuration in case there is no
> > > IRQ connected in hardware, in a manner similar to what the driver did in
> > > the very first commit which added the driver.
> > > 
> > > ACPI table dump:
> > 
> > >          Device (BMA2)
> > >          {
> > >              Name (_ADR, Zero)  // _ADR: Address
> > >              Name (_HID, "BOSC0200")  // _HID: Hardware ID
> > >              Name (_CID, "BOSC0200")  // _CID: Compatible ID
> > >              Name (_DDN, "Accelerometer")  // _DDN: DOS Device Name
> > >              Name (_UID, One)  // _UID: Unique ID
> > >              Method (_CRS, 0, NotSerialized)  // _CRS: Current Resource Settings
> > >              {
> > >                  Name (RBUF, ResourceTemplate ()
> > >                  {
> > >                      I2cSerialBusV2 (0x0019, ControllerInitiated, 0x00061A80,
> > >                          AddressingMode7Bit, "\\_SB.PCI0.I2C0",
> > >                          0x00, ResourceConsumer, , Exclusive,
> > >                          )
> > >                  })
> > >                  Return (RBUF) /* \_SB_.PCI0.I2C0.BMA2._CRS.RBUF */
> > >              }

> > >          }

...

> > As for the solution, are you sure the line is not wired at all?
> 
> No . It is some cheap mini-laptop , I have no schematics or any other info
> really .

> Note that I am not really familiar with x86 and ACPI, so there is that.

Yes, I understand that.

You can try to monitor the /sys/kernel/debug/pinctrl/*/pins files for any
changes that might happen on the sensor events. It might (help to) reveal
the IRQ line.

> > IIRC Hans had a broken tales where it was simply forgotten, meaning
> > the Android / Windows driver simply hardcoded needed info.
> > 
> > If it's the case, it should be solved differently around PDx86 special quirk
> > driver for the cases like this.
> There are likely two issues.
> 
> First, this driver needs to handle i2c_client->irq == 0 correctly if it
> should work without IRQ line, which the driver seems to indicate that it
> does. The current crashing the kernel is not the correct way of handling
> that. That's this patch, in some form.
> 
> Second, if this laptop has some IRQ line for this chip hidden somewhere,
> then it might need a quirk of sorts, sure. Is there some way to find out,
> without taking the thing apart and poking around with a scope ?

-- 
With Best Regards,
Andy Shevchenko