Re: [PATCH] touchscreen: stmpe-ts: enable module autoload

[Heiner Kallweit <hkallweit1@gmail.com>]

Am 22.05.2015 um 20:29 schrieb Dmitry Torokhov:
> On Fri, May 22, 2015 at 07:34:43AM +0200, Heiner Kallweit wrote:
>> Am 22.05.2015 um 01:06 schrieb Dmitry Torokhov:
>>> Hi Heiner,
>>>
>>> On Thu, May 21, 2015 at 11:19:52PM +0200, Heiner Kallweit wrote:
>>>> Even with poper DT config the module didn't autoload.
>>>> That's fixed by this additional alias.
>>>>
>>>> Tested successfully with a STMPE610-based Adafruit PITFT Plus 3.5"
>>>> on RPI2 under Arch Linux ARM (kernel 3.18.13).
>>>>
>>>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>>>> ---
>>>>  drivers/input/touchscreen/stmpe-ts.c | 1 +
>>>>  1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/drivers/input/touchscreen/stmpe-ts.c b/drivers/input/touchscreen/stmpe-ts.c
>>>> index e4c3125..1940e3c 100644
>>>> --- a/drivers/input/touchscreen/stmpe-ts.c
>>>> +++ b/drivers/input/touchscreen/stmpe-ts.c
>>>> @@ -393,4 +393,5 @@ module_platform_driver(stmpe_ts_driver);
>>>>  MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
>>>>  MODULE_DESCRIPTION("STMPEXXX touchscreen driver");
>>>>  MODULE_LICENSE("GPL");
>>>> +MODULE_ALIAS("spi:" STMPE_TS_NAME);
>>>>  MODULE_ALIAS("platform:" STMPE_TS_NAME);
>>>
>>> Bit this is not an SPI driver, it is a platform driver for a MFD cell.
>>> Why does adding SPI alias help?
>>>
>>> Thanks.
>>>
>> The STMPE610 in my case is used on a small touchscreen for the Raspberry Pi
>> and touchscreen controller as well as display controller are connected via
>> SPI + a few GPIOs to the RPI.
>>
>> The display controller is supported by the fbtft driver and the drivers
>> for the respective display controllers have similar aliases.
>> see e.g. drivers/staging/fbtft/fb_hx8353d.c
>>
>> MODULE_ALIAS("spi:hx8353d");
>> MODULE_ALIAS("platform:hx8353d");
> 
> I understand why both platform and spi aliases are needed for
> fb_hx8353d: FBTFT_REGISTER_DRIVER macro does register 2 separate
> drivers, one SPI and another platform, and so needs both aliases. You
> still have not explained why we need SPI alias for stmpe-ts which is MFD
> cell represented by a platform device/driver no matter what bus is used
> to connect stmpe itself, I2C or SPI.
> 
> What is the modalias on the stmpe-ts device in sysfs?
> 
> Thanks.
> 
These are the stmpe-related entries under /sys/devices:

./soc/3f204000.spi/spi_master/spi0/spi0.1/stmpe-gpio
./soc/3f204000.spi/spi_master/spi0/spi0.1/stmpe-ts

stmpe-ts/modalias is:
of:Nstmpe_touchscreenT<NULL>Cst,stmpe-ts

I also tried setting the of_match_table element of the driver struct
to "st,stmpe-ts". But this didn't work help.
Only defining this spi alias enables autoload for whatever reason.

Heiner