Re: [PATCH v2] input: touchscreen: edt-ft5x06: fix driver autoprobing

Hi Wolfram,

On Tue, Nov 18, 2014 at 02:19:07PM -0600, Felipe Balbi wrote:

On Tue, Nov 18, 2014 at 12:14:21PM -0800, Dmitry Torokhov wrote:

quoted

On Tue, Nov 18, 2014 at 02:03:40PM -0600, Felipe Balbi wrote:

quoted

On Tue, Nov 18, 2014 at 11:59:02AM -0800, Dmitry Torokhov wrote:

quoted

On Tue, Nov 18, 2014 at 01:27:42PM -0600, Felipe Balbi wrote:

quoted

Because with OF we can pass more specific
compatible flags (such as edt-ft5306) instead
of generic edt-ft5x06, when i2c-core's
of_i2c_register_devices() tries to request_module(),
it'll request it with a non-existent specific module
alias.

In order to have this driver autoprobing again, we
just need to add missing MODULE_ALIAS() entries to
edt-ft5x06 driver.

Thanks to Dmitry for noticing that it actually should
autoprobe even with of_device_id.

Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: <redacted>
Cc: <redacted> # v3.15+
Fixes: dac90dc2 (Input: edt-ft5x06 - add DT support)
Signed-off-by: Felipe Balbi <redacted>
---
 drivers/input/touchscreen/edt-ft5x06.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/input/touchscreen/edt-ft5x06.c b/drivers/input/touchscreen/edt-ft5x06.c
index ee3434f..bcbf688 100644
--- a/drivers/input/touchscreen/edt-ft5x06.c
+++ b/drivers/input/touchscreen/edt-ft5x06.c

@@ -1147,6 +1147,9 @@ static struct i2c_driver edt_ft5x06_ts_driver = {
 
 module_i2c_driver(edt_ft5x06_ts_driver);
 
+MODULE_ALIAS("i2c:edt-ft5206");
+MODULE_ALIAS("i2c:edt-ft5306");
+MODULE_ALIAS("i2c:edt-ft5406");
 MODULE_AUTHOR("Simon Budig <simon.budig@kernelconcepts.de>");
 MODULE_DESCRIPTION("EDT FT5x06 I2C Touchscreen Driver");
 MODULE_LICENSE("GPL");

-- 
2.1.0.GIT

Here is what I see if I run modinfo on the module:

dtor@dtor-ws:~/kernel/work$ modinfo
drivers/input/touchscreen/edt-ft5x06.ko
filename:
/home/dtor/kernel/work/drivers/input/touchscreen/edt-ft5x06.ko
license:        GPL
description:    EDT FT5x06 I2C Touchscreen Driver
author:         Simon Budig [off-list ref]
alias:          i2c:edt-ft5x06
alias:          of:N*T*Cedt,edt-ft5406*
alias:          of:N*T*Cedt,edt-ft5306*
alias:          of:N*T*Cedt,edt-ft5206*
depends:        i2c-core
intree:         Y
vermagic:       3.17.0+ SMP preempt mod_unload 

As you can see we already have what I consider proper modaliases for the
driver. Why don't they work? Is it because modprobe doe snot know how to
handle OF-style modaliases or device's uevents are missing OF data in
them?

no, it's because i2c call request_module for i2c:edt-ft5306. i2c core
never uses any of the of aliases.

1. I think both i2c and spi are cheating in this regard: they should
rely on normal driver request paths through udev.

2. I2C should emit proper modalias for devices coming by the way of
devicetree. It already does special handling for ACPI, it needs to do
the same for OF. I think SPI does the right thing there.

I'll let Wolfram comment here for I2C.

Can you comment on this ? As of today i2c-based drivers will probe with
DT-based boot if DT's compatible is set to the same id as in struct
i2c_device_id. No i2c driver with of_device_id can autoprobe using OF
ids.

cheers

-- 
balbi