Re: mxs_lradc_ts: Warning due to "0 is an invalid IRQ number"

[Andy Shevchenko <andriy.shevchenko@intel.com>]

+Cc: Marc in case I'm utterly wrong in my conclusion below.

On Wed, Jul 01, 2020 at 05:41:45PM -0500, Bjorn Helgaas wrote:
> On Wed, Jul 01, 2020 at 12:32:48PM -0300, Fabio Estevam wrote:
> > On Tue, Jun 16, 2020 at 8:52 PM Fabio Estevam <festevam@gmail.com> wrote:
> > > I am seeing the following warning on a imx28-evk running linux-next:
> > >
> > > [    7.625012] ------------[ cut here ]------------
> > > [    7.630111] WARNING: CPU: 0 PID: 1 at drivers/base/platform.c:317
> > > __platform_get_irq_byname+0x74/0x90
> > > [    7.639692] 0 is an invalid IRQ number
> > > [    7.643540] Modules linked in:
> > > [    7.646961] CPU: 0 PID: 1 Comm: swapper Not tainted
> > > 5.8.0-rc1-next-20200616-dirty #92
> > > [    7.654896] Hardware name: Freescale MXS (Device Tree)
> > > [    7.660434] [<c00105ec>] (unwind_backtrace) from [<c000e070>]
> > > (show_stack+0x10/0x14)
> > > [    7.668591] [<c000e070>] (show_stack) from [<c001aa90>] (__warn+0xe4/0x108)
> > > [    7.675941] [<c001aa90>] (__warn) from [<c001ab20>]
> > > (warn_slowpath_fmt+0x6c/0xb8)
> > > [    7.683575] [<c001ab20>] (warn_slowpath_fmt) from [<c0491b44>]
> > > (__platform_get_irq_byname+0x74/0x90)
> > > [    7.693101] [<c0491b44>] (__platform_get_irq_byname) from
> > > [<c0491b70>] (platform_get_irq_byname+0x10/0x48)
> > > [    7.703154] [<c0491b70>] (platform_get_irq_byname) from
> > > [<c056e234>] (mxs_lradc_ts_probe+0x190/0x384)
> > > [    7.712771] [<c056e234>] (mxs_lradc_ts_probe) from [<c0491850>]
> > > (platform_drv_probe+0x48/0x98)
> > > [    7.722806] [<c0491850>] (platform_drv_probe) from [<c048f7f0>]
> > > (really_probe+0x218/0x348)
> > > [    7.731530] [<c048f7f0>] (really_probe) from [<c048fa28>]
> > > (driver_probe_device+0x58/0xb4)
> > > [    7.740189] [<c048fa28>] (driver_probe_device) from [<c048fc2c>]
> > > (device_driver_attach+0x58/0x60)
> > > [    7.749471] [<c048fc2c>] (device_driver_attach) from [<c048fcb8>]
> > > (__driver_attach+0x84/0xc0)
> > > [    7.758394] [<c048fcb8>] (__driver_attach) from [<c048db28>]
> > > (bus_for_each_dev+0x70/0xb4)
> > > [    7.766977] [<c048db28>] (bus_for_each_dev) from [<c048eb24>]
> > > (bus_add_driver+0x154/0x1e0)
> > > [    7.775385] [<c048eb24>] (bus_add_driver) from [<c0490774>]
> > > (driver_register+0x74/0x108)
> > > [    7.783872] [<c0490774>] (driver_register) from [<c000a2fc>]
> > > (do_one_initcall+0x68/0x268)
> > > [    7.792467] [<c000a2fc>] (do_one_initcall) from [<c0a00fa0>]
> > > (kernel_init_freeable+0x160/0x1f4)
> > > [    7.801661] [<c0a00fa0>] (kernel_init_freeable) from [<c0720c58>]
> > > (kernel_init+0x8/0xf4)
> > > [    7.810165] [<c0720c58>] (kernel_init) from [<c0008510>]
> > > (ret_from_fork+0x14/0x24)
> > > [    7.818101] Exception stack(0xc748dfb0 to 0xc748dff8)
> > > [    7.823273] dfa0:                                     00000000
> > > 00000000 00000000 00000000
> > > [    7.831815] dfc0: 00000000 00000000 00000000 00000000 00000000
> > > 00000000 00000000 00000000
> > > [    7.840351] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
> > > [    7.847322] irq event stamp: 273303
> > > [    7.850940] hardirqs last  enabled at (273311): [<c0066ed8>]
> > > console_unlock+0x390/0x534
> > > [    7.859314] hardirqs last disabled at (273328): [<c0066b8c>]
> > > console_unlock+0x44/0x534
> > > [    7.867605] softirqs last  enabled at (273344): [<c00097fc>]
> > > __do_softirq+0x2d4/0x450
> > > [    7.875817] softirqs last disabled at (273355): [<c001fe48>]
> > > irq_exit+0x150/0x174
> > > [    7.883472] ---[ end trace ddb222ada5cbf5cd ]---
> > > [    7.900004] input: mxs-lradc-ts as
> > > /devices/soc0/80000000.apb/80040000.apbx/80050000.lradc/mxs-lradc-ts/input/input0
> > >
> > > The touchscreen irq is defined as:
> > >
> > > enum mx28_lradc_irqs {
> > > MX28_LRADC_TS_IRQ = 0,
> > >
> > > Shouldn't we retrieve the IRQ number from the device tree instead?
> 
>   mxs_lradc_ts_probe()
>   {
>     ...
>     irq = platform_get_irq_byname(pdev, mxs_lradc_ts_irq_names[i]);
>     if (irq < 0)
> 	    return irq;
> 
>     virq = irq_of_parse_and_map(node, irq);
>     ...
>   }
> 
> That's not right, is it?  irq_of_parse_and_map() takes an *index*, but
> we're passing an IRQ.
> 
> mxs_lradc_adc_probe() also has the same pattern.

Yeah, you are right. This code is broken by design. But the issue is that MFD
driver supplies _index_ and not vIRQ from proper IRQ domain. I dunno how it's
supposed to work without dirty tricks in the GIC (or whatever interrupt
controller is there).

Since there is no response to this thread by the authors of the code, I would
mark it as BROKEN and perhaps remove from the kernel if no-one steps in to fix
this mess.

-- 
With Best Regards,
Andy Shevchenko