Messages in this thread | | | Date | Sun, 20 Apr 2014 18:31:18 +0800 | From | "Jin, Yao" <> | Subject | Re: [PATCH] pinctrl-baytrail: fix for irq descriptor conflict on ASUS T100TA |
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On 2014/4/19 4:44, Benjamin Tissoires wrote: > On Wed, Apr 16, 2014 at 8:05 AM, Jin Yao <yao.jin@linux.intel.com> wrote: >> A crash is triggered on the ASUS T100TA Baytrail-T because of a irq >> descriptor conflict. There are two gpio triggered acpi events in this >> device, GPIO 6 and 18. These gpios are translated to irqs by calling >> gpio_to_irq which in turn will call irq_create_mapping(vg->domain, offset). >> irq_create_mapping will take care of allocating the irq descriptor, taking >> the first available number starting from the given value (6 in our case). >> The 0-15 are already reserved by legacy ISA code, so it gets the first >> free irq descriptor which is number 16. The i915 driver also uses irq 16, >> it loads later than gpio and crashes in probe. >> >> The bug is reported here: >> https://bugzilla.kernel.org/show_bug.cgi?id=68291 > > Adam, the reporter of this bug told me that his touchscreen was broken > in its tablet. This bug is triggered when system boots, or rather, it's triggered in i915 probe, because i915 still uses irq 16 but it's allocated for gpio yet. It's not a touchscreen case.
> I strongly suspect this patch to be the root cause of this, because > the touchscreen uses i2c_hid. i2c_hid relies on an IRQ declared in the > DSDT when it is acpi enumerated, and since the inclusion of this > patch, no irq are triggered from a driver point of view. > > Adam should still confirm that the revert of the patch makes the > touchscreen back alive, but if I understood correctly the bug report, > without the patch, his tablet oopses at boot. Do you mean this patch cause the touchscreen doesn't work? I suspect that because the touch screen works on my T100 with this patch.
> > Still, it would be good if you could check that shifting the irqs in > the pinctrl is or is not a problem with the irqs used for i2c devices > (and others) declared in the dsdt. I checked DSDT of ASUS T100, looks no irq conflict after irq shifting.
> > Cheers, > Benjamin > >> >> The rootcause we know now is a low level irq issue. It needs a long term >> solution to fix the issue in irq system. >> >> This patch changes the Baytrail GPIO driver to avoid the irq descriptor >> conflict. It still uses the irq domain to allocate irq descriptor but start >> from a predefined irq base number (256) to avoid the conflict. >> >> Signed-off-by: Jin Yao <yao.jin@linux.intel.com> > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
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