Hi,

On 06/13/2014 12:15 PM, Maxime Ripard wrote:
> On Fri, Jun 13, 2014 at 11:54:06AM +0200, Hans de Goede wrote:
>> Hi,
>>
>> On 06/13/2014 10:40 AM, Maxime Ripard wrote:
>>> On Fri, Jun 13, 2014 at 09:32:20AM +0200, Hans de Goede wrote:
>>>> Hi,
>>>>
>>>> On 06/13/2014 12:48 AM, [email protected] wrote:
>>>>> On Thu, Jun 12, 2014 at 6:35 PM, Emilio López <[email protected]> 
>>>>> wrote:
>>>>>> El 12/06/14 19:11, [email protected] escribió:
>>>>>>
>>>>>>> What has replaced sw_get_ic_ver() on 3.15?
>>>>>>>
>>>>>>> Codec code varies on every chip revision A,B,C and A10/20.
>>>>>>
>>>>>>
>>>>>> A10/A20 can be determined by the compatible string. Chip revision is 
>>>>>> going
>>>>>> to be trickier though, there is no direct replacement of sw_get_ic_ver()
>>>>>> that I'm aware of. sw_get_ic_ver() seems to poke a timer register in the
>>>>>> sun4i case, and SID (for which we do have a driver[1]) on the sun5i case.
>>>>>>
>>>>>> [1] drivers/misc/eeprom/sunxi_sid.c
>>>>>
>>>>> We may have to reimplement it. Codec driver has stuff like this in it.
>>>>
>>>> I think adding some sort of SoC version detection makes sense, so go for 
>>>> it.
>>>
>>> It might, and we probably will come to it eventually, but I don't get
>>> what it would bring here.
>>>
>>> Have different compatible strings for the various revisions of the IP
>>> is much simpler and adds no code at all.
>>
>> That assumes that for a single board only a single revision of the SoC has
>> ever been used. I would not be so sure that that is the case, I'm pretty
>> sure that there were various rruns of the original mk802 A10 version,
>> likely with the first runs having A10 Revision A and later runs
>> revision B. I really don't want to have to do different dts files just
>> to deal with this, that is not helpful from a maintenance pov, and it
>> will also only serve to confuse our end users as they will have no idea
>> which revision of the SoC they have, so solving the differences between
>> the A10 revision A vs B/C with a compatible string seems counter productive.
> 
> There's usually two patterns to deal with this:
>   - Either have two different DT, depending on the revision of the
>     board
> 
>   - If the board rev hasn't changed, have the machine code come and
>     update the DT with the appropriate compatible (see
>     http://lxr.free-electrons.com/source/arch/arm/mach-mvebu/board-v7.c#L71)
> 
> The latter is much better, for the reasons you mentionned, but in any
> case, the driver itself shouldn't have to worry about that kind of
> things, and only deal with compatibles.

OK, then lets do something like the latter. jonsmirl while at it, can
you also add a pr_info printing the exact SoC revision detected to
the machine code, that is very likely going to be quite useful one
of these days.

Regards,

Hans

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