Re: [PATCH] gpio/ls1043a: Correct ls1043a gpio nodes compatible in dts file

[Scott Wood <scott.wood@xxxxxxx>]

On 03/17/2016 01:57 AM, Gang Liu wrote:
> On 3/17/2016 2:47 AM, Scott Wood wrote:
>> On 03/10/2016 03:06 AM, Liu Gang wrote:
>>> The ls1043a belongs to the Freescale QorIQ platform, and QorIQ
>>> platform's gpio nodes should use compatible "fsl,qoriq-gpio".
>> Why?  I don't see any version register anything else in this block that
>> could be used to identify potential differences from chip to chip.  At
>> the least, both compatibles should be present.
>>
>> Where is the binding for this?
>>
>> -Scott
>>
>>
> Hi, Scott,
> Currently all QorIQ platform's GPIO IP blocks are same, they are all no
> version register,
> and have same registers, offset address and other features, so the code
> can cover all of
> them.

So?  We have no idea what the hardware people will do in the future.

> There is just one exceptional ls2080, it has the little-endian GPIO
> registers, and we added
> a "little-endian" property in the GPIO nodes.
> 
> Add in addition, we have deeply discussed about the GPIO compatible name
> before, you
> suggested using "fsl,qoriq-gpio" for all the QorIQ platforms. Please
> find some excerpt
> from former mail context.

It's in established use so I won't suggest that we get rid of it.  But
ideally the chip-specific compatible should be in the device tree (not
the driver until/unless necessary) as well, so it seemed odd to get rid
of it.

If we were starting from scratch, then instead of "fsl,qoriq-gpio" it
should have been a chip-based compatible for some arbitrary chip that
contains this exact logic (in addition to the chip-specific compatible
for the actual chip).  Neither case requires adding every chip name to
the driver.

-Scott

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