On Tue, 2015-06-23 at 13:23 +0000, Tirdea, Irina wrote: > > > -----Original Message----- > > From: linux-input-owner@xxxxxxxxxxxxxxx [mailto: > > linux-input-owner@xxxxxxxxxxxxxxx] On Behalf Of Bastien Nocera > > Sent: 09 June, 2015 18:53 > > To: Tirdea, Irina > > Cc: Dmitry Torokhov; Mark Rutland; linux-input@xxxxxxxxxxxxxxx; > > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Rob > > Herring; Pawel Moll; Ian Campbell; Kumar Gala; Purdila, Octavian > > Subject: Re: [PATCH v2 4/8] input: goodix: reset device at init > > > > On Tue, 2015-06-09 at 17:34 +0200, Bastien Nocera wrote: > > > On Mon, 2015-06-08 at 17:37 +0300, Irina Tirdea wrote: > > > > After power on, it is recommended that the driver resets the > > > > device. > > > > The reset procedure timing is described in the datasheet and is > > > > used > > > > at device init (before writing device configuration) and > > > > for power management. It is a sequence of setting the interrupt > > > > and reset pins high/low at specific timing intervals. This > > > > procedure > > > > also includes setting the slave address to the one specified in > > > > the > > > > ACPI/device tree. > > > > > > This breaks the touchscreen on my Onda v975w: > > > [ 239.732858] Goodix-TS i2c-GDIX1001:00: ID 9271, version: 1020 > > > [ 239.732977] Goodix-TS i2c-GDIX1001:00: Failed to get reset > > > GPIO: > > > -16 > > > [ 239.736071] Goodix-TS: probe of i2c-GDIX1001:00 failed with > > > error > > > -16 > > > > > > This is the DSDT for that device: > > > https://bugzilla.kernel.org/attachment.cgi?id=149331 > > > > Oops. That's right - I am using named interrupts which are available > only for ACPI 5.1, so > devices already out there will not work. > > The problem here is that handling -ENOENT will not help. The gpio > pins are declared in the > ACPI DSDT, but are not named. The devm_gpiod_get API will look for > the named interrupt > first and fallback to searching by index if not found. Index will be > 0 in both cases, this is why > the first call will succeed and the second will fail with -EBUSY. > > One way to handle this would be to use indexed gpio pins instead of > named gpio pins: > e.g. consider the first gpio pin to be the reset pin and the second > to be the interrupt pin. > This is used in other drivers as well, e.g. zforce_ts. The problem > with this approach is that > any devices that declare the gpio pins in reversed order in the DSDT > will not work and give > no warning (the pins will be requested successfully, but some of the > functionality will not > work). The DSDT mentioned in > https://bugzilla.kernel.org/attachment.cgi?id=149331 lists > the reset pin first, while I am working on some devices that declare > the interrupt gpio pin > first. > > Another way to handle this is to treat -EBUSY like -ENOENT and not > use any functionality > that depends on the gpio pins. Unfortunately, this means we will not > have suspend, esd and > custom configs even if the pins are connected on the board and > available in ACPI(just not > named). > > I would go with the first approach and document the order requested > for the pins, but I would > like to hear what you think first. Is there a better way to do this? > > > (Note that this means that I haven't been able to test any > > following > > patches in that series than 4/8). > > Sure, that makes sense. The following patches depend on the gpio pins > so they would not have > worked either. We can apply quirks based on DMI information, so that devices with ACPI in different orders will work after applying a quirk (as long as there's a way to detect that it's in the wrong order, obviously). -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
