On Mon, Feb 17, 2014 at 9:02 AM, Magnus Damm <magnus.damm@xxxxxxxxx> wrote:
> On Mon, Feb 17, 2014 at 4:54 PM, Wolfram Sang <wsa@xxxxxxxxxxxxx> wrote:
>> On Sun, Feb 16, 2014 at 10:40:55AM +0100, Wolfram Sang wrote:
>>> From: Wolfram Sang <wsa@xxxxxxxxxxxxxxxxxxxx>
>>>
>>> Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxxxxxxxxx>
>>
>> From your other mail:
>>
>> "[2/5] needs to be reworked to exclude the r8a7790 compatible string."
>>
>>> + compatible = "renesas,i2c-r8a7791", "renesas,i2c-r8a7790";
>>
>> Why is that? From my knowledge, you start with the exact compatible
>> property and hardware compatible entries may follow.
Thanks for posting the link to the device tree wiki/quoting from it.
I had faint memories of that quote, but couldn't remember where I read it.
> I think this boils down to if they really are compatible or not. If
> for instance a 16550 port would be compatible with 8250 on a hardware
> level then using them in the order of "16550", "8250" makes sense. In
> this case the r8a7791 i2c is not really strictly based on r8a7790 i2c,
> it is just that r8a7790 has support in the driver. So it's a short cut
> instead of actual hardware compatibility.
>
> So far we've dealt with this by updating the driver and only relying
> on the actual SoC name as suffix.
>
> I'm sure there are tons of opinions. =)
Hehe ;-)
I think the tricky part is when a driver for "renesas,i2c-r8a7790" is updated
with a new feature for r8a7790, which doesn't necessarily exist in r8a7791.
Then the compatible entry above will cause breakage.
In our case, this probably won't happen, as we will have "renesas,i2c-r8a7791"
in the driver, but the driver could be forked in between the addition of
"renesas,i2c-r8a7790" and "renesas,i2c-r8a7791" in our non-ideal world.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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