[uclinux-dist-devel] touch screen ads7846/7843 devicetree support

[Barry Song]

2011/2/3 Grant Likely <grant.likely at secretlab.ca>:
> On Thu, Jan 27, 2011 at 12:24:01PM +0000, Hennerich, Michael wrote:
>> Thomas Chou wrote on 2011-01-27:
>> > On 01/27/2011 02:18 PM, Mike Frysinger wrote:
>> >> On Thu, Jan 27, 2011 at 01:10, Thomas Chou wrote:
>> >>> We need devicetree support on ads7846/7843 touch screen driver. Do
>> >>> you have plan on it? We are moving to devicetree on nios2, so do
>> > arm/mips/x86.
>> >>
>> >> what part are you using exactly ?
>> >> -mike
>> >>
>> >
>> > ad7843 is used in a popular nios2 dev kit, NEEK.
>>
>> This driver is a SPI bus client driver. PPC is using devicetree for ages now,
>> and they don't have problems instantiating this or any other SPI bus driver.
>
> However, the method used is by applying a heuristic (of_modalias_node)
> which tries to name the device in a way that will match an existing
> device driver.  It works for a lot of spi drivers, but it isn't
> always reliable.
>
> Alternatively, if of_match_table is populated in the spi_driver, then
> the normal device tree match behaviour will always work.

not like i2c_driver and platform_driver, it is really difficult to
find many spi client drivers using device tree fo the moment. most spi
boards still use spi_board_info to register spi client. these spi
client drivers do work well with spi host based on device tree at most
cases. the ideal spi client should be a child node of spi host in
device tree, then use of_match_table to get probed.
i am working on ads7846 as an example for our team to use device tree
in spi client drivers and will send a patch.

BTW, is ads7846 from TI? or am i wrong? why is this question posted in
ADI' maillist?

>
> g.
>
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