Re: [PATCH v3] Input - surface3_spi: add new driver for the Surface 3

On May 17 2016 or thereabouts, Benjamin Tissoires wrote:

On May 17 2016 or thereabouts, Dmitry Torokhov wrote:

quoted

Hi Benjamin,

On Tue, May 17, 2016 at 12:16:19PM +0200, Benjamin Tissoires wrote:

quoted

This is a basic driver for the Surface 3. I am not so sure it will work
with any firmwares as most values are encoded, but given that I only have
access to my current device with its firmware and I don't have the
datasheet, it should be OK for now.

The Surface Pen is not supported (if it is supposed to be). I'll work on
this when I get one.

Signed-off-by: Benjamin Tissoires <redacted>
---
Changes in v2:

- module renamed from ntrig_spi to surface3_spi
- took into account Dmitry's remarks
- kept the retrieval of the GPIO as mandatory as otherwise the device fails to work

Changes in v3:

- asm include put at the end
- used proper types in struct surfacae3_ts_data_finger
- dropped temps in surface3_spi_report_touch()
- inlined surface3_spi_request_irq()
- detect IRQ type (falling/rising) depending on the gpiod active low parameter

I do not think that this should be done in the driver. The device either
has interrupt descriptor or GpioInt decriptor in DSDT and SPI core/ACPI
should do the right thing and configure GPIO as input and set interrupt
polarity accordingly, so when you do request_threaded_irq() you only
need to specify IRQF_ONESHOT.

See drivers/spi/spi.c - in case there is no interrupt specified we call
acpi_dev_gpio_irq_get(). Do you see it called in your case? Or your DSDT
has interrupt for the touchscreen device and acpi_spi_add_resource() and
acpi_dev_resource_interrupt() are called? You need to trace it and
figure out if there is an issue there with setting up interrupt
properly.

Looks like I need to push further the tests. From what I can see, using
just IRQF_ONESHOT is not sufficient enough and I need to add the trigger
falling manually (thus this way of doing).

I think I finally got it: I traced irq_get_irq_type() just before
calling devm_request_threaded_irq(), and the trigger flag was properly set.
The thing is that the IRQ was triggered only if I actually set the
trigger in the flag (using "IRQF_ONESHOT | irq_get_irq_type(spi->irq)"
was making it working).

And the final problem I had was that I was requesting the gpiod
for the interrupt. I think this just messed up the gpiochip
configuration and the request irq needs to reset it properly.

So removing a bunch of lines of code solves it :)
(I know, you already told me to remove it in v1, but it did not work at
that time :-P ).

v4 on its way after a few more tests.

Cheers,
Benjamin