netdev - Re: [PATCH 4/4] wl1251: spi: add device tree support

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Date:	Tue, 29 Oct 2013 03:28:39 -0500
From:	Kumar Gala <galak@...eaurora.org>
To:	Tomasz Figa <tomasz.figa@...il.com>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Sebastian Reichel <sre@...ian.org>,
	Mark Rutland <mark.rutland@....com>, linux-doc@...r.kernel.org,
	Tony Lindgren <tony@...mide.com>,
	Russell King <linux@....linux.org.uk>,
	Sachin Kamat <sachin.kamat@...aro.org>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Sebastian Reichel <sre@...g0.de>,
	Luciano Coelho <luca@...lho.fi>, devicetree@...r.kernel.org,
	Pawel Moll <pawel.moll@....com>,
	Stephen Warren <swarren@...dotorg.org>,
	"John W. Linville" <linville@...driver.com>,
	Rob Herring <rob.herring@...xeda.com>,
	Bill Pemberton <wfp5p@...ginia.edu>,
	linux-omap@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
	Felipe Balbi <balbi@...com>, Rob Landley <rob@...dley.net>,
	netdev@...r.kernel.org
Subject: Re: [PATCH 4/4] wl1251: spi: add device tree support


On Oct 28, 2013, at 5:38 PM, Tomasz Figa wrote:

> On Monday 28 of October 2013 01:37:34 Kumar Gala wrote:
>> On Oct 27, 2013, at 11:14 AM, Sebastian Reichel wrote:
>>> Add device tree support for the spi variant of wl1251
>>> and document the binding.
>>> 
>>> Signed-off-by: Sebastian Reichel <sre@...ian.org>
>>> ---
>>> .../devicetree/bindings/net/wireless/ti,wl1251.txt | 36
>>> ++++++++++++++++++++++ drivers/net/wireless/ti/wl1251/spi.c          
>>>    | 23 ++++++++++---- 2 files changed, 53 insertions(+), 6
>>> deletions(-)
>>> create mode 100644
>>> Documentation/devicetree/bindings/net/wireless/ti,wl1251.txt
>>> 
>>> diff --git
>>> a/Documentation/devicetree/bindings/net/wireless/ti,wl1251.txt
>>> b/Documentation/devicetree/bindings/net/wireless/ti,wl1251.txt new
>>> file mode 100644
>>> index 0000000..5f8a154
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/net/wireless/ti,wl1251.txt
>>> @@ -0,0 +1,36 @@
>>> +* Texas Instruments wl1251 controller
>>> +
>>> +The wl1251 chip can be connected via SPI or via SDIO. The linux
>>> +kernel currently only supports device tree for the SPI variant.
>>> +
>> 
>> From the binding I have no idea what this chip actually does, also we
>> don't normally reference linux kernel support in bindings specs (so
>> please remove it).
>> 
>> However, what would expect the SDIO binding to look like?  Or more
>> specifically, how would you distinguish the SPI vs SDIO
>> binding/connection?  I'm wondering if the compatible should be
>> something like "ti,wl1251-spi" and than the sdio can be
>> "ti,wl1251-sdio"
> 
> Well, you can easily distinguish an SDIO device from an SPI device by its 
> parent node, but...
> 
> The binding for SDIO might require different set of properties (other than 
> ones inherited from generic SDIO or SPI bindings) than one for SPI. So 
> probably different compatible values might be justified.
> 
> Did we already have such case before? (maybe some I2C + SPI devices?)
> 
>>> +Required properties:
>>> +- compatible : Should be "ti,wl1251"
>> 
>> reg is not listed as a required prop.
> 
> It is implied by SPI bindings, but it might be a good idea to have this 
> stated here as well.
> 
>> 
>>> +- interrupts : Should contain interrupt line
>>> +- interrupt-parent : Should be the phandle for the interrupt
>>> +  controller that services interrupts for this device
>>> +- vio-supply : phandle to regulator providing VIO
>>> +- power-gpio : GPIO connected to chip's PMEN pin
>> 
>> should be vendor prefixed: ti,power-gpio
> 
> Hmm, out of curiosity, is it a rule for this kind of properties? I can see 
> both cases with and without prefixes when grepping for "-gpios" in 
> Documentation/devicetree/bindings. We should really have such things 
> written down somewhere.

Agreed, it should be part of the various docs we are suppose to produce for review and binding creation guidelines.

>>> +- For additional required properties on SPI, please consult
>>> +  Documentation/devicetree/bindings/spi/spi-bus.txt
>>> +
>>> +Optional properties:
>>> +- ti,use-eeprom : If found, configuration will be loaded from eeprom.
>> 
>> can you be a bit more specific on what cfg will be loaded.  Also, is
>> this property a boolean, if so how do I know which eeprom the cfg is
>> loaded from (is it one that is directly connected to the wl1251?
> 
> Maybe one from ti,has-eeprom or ti,config-eeprom would be better name for 
> this property?

Probably, ti,wl1251-has-eeprom or something like that would be better.  However, I'm not going to get too caught up on names of properties.

- k

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

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