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SubjectRE: [PATCH v3 1/5] Input: goodix - reset device at init
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> -----Original Message-----
> From: Bastien Nocera [mailto:hadess@hadess.net]
> Sent: 25 September, 2015 17:44
> To: Tirdea, Irina; linux-input@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org; Rob Herring; Pawel Moll; Ian Campbell; Kumar Gala; Purdila, Octavian; Dmitry Torokhov; Mark
> Rutland; devicetree@vger.kernel.org
> Subject: Re: [PATCH v3 1/5] Input: goodix - reset device at init
>
> On Thu, 2015-09-10 at 14:04 +0000, Tirdea, Irina wrote:
> >
> > > -----Original Message-----
> > > From: Bastien Nocera [mailto:hadess@hadess.net]
> > > Sent: 09 September, 2015 20:03
> > > To: Tirdea, Irina; linux-input@vger.kernel.org
> > > Cc: linux-kernel@vger.kernel.org; Rob Herring; Pawel Moll; Ian
> > > Campbell; Kumar Gala; Purdila, Octavian; Dmitry Torokhov; Mark
> > > Rutland; devicetree@vger.kernel.org
> > > Subject: Re: [PATCH v3 1/5] Input: goodix - reset device at init
> > >
> > > On Thu, 2015-07-30 at 11:27 +0000, Tirdea, Irina wrote:
> > > > I can send some additional patches that will simplify testing the
> > > > configuration update to the Goodix device. I think this feature
> > > > is
> > > > the easiest
> > > > to test so we can determine if writing to the interrupt pin
> > > > actually
> > > > works.
> > > > However, even if it is a BIOS problem and the code will work, the
> > > > warning
> > > > will still be printed in dmesg.
> > >
> > >
> > > Somehow missed this mail before replying to the current patchset.
> > > I'd
> > > be fine with that, though it's still not clear to me whether the
> > > BIOS/hardware is at fault, or the code that's being added to the
> > > driver
> > > ;)
> > >
> >
> > The reset procedure is described in the Goodix GT911 datasheet [1]
> > and is
> > used for power-on reset and power management. The power-on sequence
> > is described in chapter 6.1. I2C Timing, in the Power-on Timing
> > diagram.
> > The sequence for putting the device to sleep is described in chapter
> > 7.1. Operating Modes, c) Sleep mode. These sequences use the
> > interrupt
> > pin as output.
> >
> > The warning you mentioned comes from the following code in the goodix
> > driver, which sets the interrupt to be used as output:
> >
> > +       error = gpiod_direction_output(ts->gpiod_int, ts->client-
> > >addr == 0x14);
> >
> > The gpiod_direction_output() call ends up in
> > drivers/pinctrl/intel/pinctrl-baytrail.c:
> > /*
> >  * Before making any direction modifications, do a check if gpio
> >  * is set for direct IRQ.  On baytrail, setting GPIO to output does
> >  * not make sense, so let's at least warn the caller before they
> > shoot
> >  * themselves in the foot.
> >  */
> > WARN(readl(conf_reg) & BYT_DIRECT_IRQ_EN,
> > "Potential Error: Setting GPIO with direct_irq_en to output");
> >
> > So the problem comes from using the gpio interrupt pin as output,
> > which
> > should not work on Baytrail if BYT_DIRECT_IRQ_EN is set by BIOS.
> > The above warning is introduced and discussed in [2] and [3]. As I
> > mentioned,
> > this could be a real HW issue or the BIOS sets BYT_DIRECT_IRQ_EN when
> > it should not. I have also tested these patches on a Baytrail
> > plarform
> > (that uses the same pinctrl driver), but I did not see any issues
> > since
> > BYT_DIRECT_IRQ_EN is not set in my case for the interrupt gpio pin.
>
> Do we have a way to work-around this in the GPIO driver?
>
> > To determine if using the interrupt pin as output works, you can test
> > updating
> > the goodix configuration [4].
>
> Right, the problem being that it's a later patch in the branch, and
> that the driver will fail to probe if there's an error from the GPIO
> call.
>

The warning from your dmesg output will not cause probe to fail.
If you look at the code for byt_gpio_direction_output, it will just print
a warning and continue [1]:
WARN(readl(conf_reg) & BYT_DIRECT_IRQ_EN,
"Potential Error: Setting GPIO with direct_irq_en to output");
I thought probe finishes successfully, but due to the warning in dmesg you
are not sure whether the IRQ GPIO pin can be used as output.
If probe fails, it must be for another reason than the direct_irq_en warning.

> Would you have a patch for me to test that would bypass this error, or
> at least fallback gracefully to not resetting, not probing GPIOs if
> they're badly setup?

If the driver fails to initialize the GPIOs, it will at least print some
"Failed to get GPIO" warnings in dmesg. Do you have such messages in
dmesg or any additional information on why probe fails?

The current code will ignore GPIOs if they are not defined in ACPI
(see the check for -ENOENT), but does not ignore other error codes.
If you want to bypass all GPIO errors, you can use the code below.

Thanks,
Irina

diff --git a/drivers/input/touchscreen/goodix.c b/drivers/input/touchscreen/goodix.c
index 9c58583..f7ec0ba 100644
--- a/drivers/input/touchscreen/goodix.c
+++ b/drivers/input/touchscreen/goodix.c
@@ -528,9 +528,7 @@ static int goodix_ts_probe(struct i2c_client *client,
ts->client = client;
i2c_set_clientdata(client, ts);

- error = goodix_get_gpio_config(ts, id);
- if (error)
- return error;
+ goodix_get_gpio_config(ts, id);

if (ts->gpiod_int && ts->gpiod_rst) {
/* reset the controller */

[1] http://lxr.free-electrons.com/source/drivers/pinctrl/intel/pinctrl-baytrail.c#L337

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