RE: [PATCH 0/6] i2c-imx-lpi2c: add IPG clock

[Peng Fan]

> Subject: Re: [PATCH 0/6] i2c-imx-lpi2c: add IPG clock
> 
> On 15/08/2022 03:52, Peng Fan wrote:
> > Hi Krzysztof,
> >
> >> Subject: Re: [PATCH 0/6] i2c-imx-lpi2c: add IPG clock
> >>
> >> On 12/08/2022 07:34, Peng Fan (OSS) wrote:
> >>> From: Peng Fan <peng.fan@xxxxxxx>
> >>>
> >>> The i.MX LPI2C needs PER and IPG clock, not just PER or IPG clock.
> >>> This patch is to enable both PER and IPG clock for imx-i2c-lpi2c.
> >>
> >> This patchset breaks the ABI and is not bisectable. The justification
> >> is very limited (one sentence), so not really enough.
> >
> > ARM32 i.MX7ULP and ARM64 i.MX8QXP/i.MX8ULP all need to use two
> clocks,
> > PER and IPG. But current dt-bindings and dts, use one clock.
> >
> > This patchset includes dts changes patch 4 and patch 5.
> > Patch 6 is to update driver use two clocks.
> >
> > I think the patch order in this patchset would not break git bisect,
> > it just break ABI. But I not find good way how could not break ABI,
> > because only use one clock is wrong whether in dt-bindings or dtbs.
> 
> Driver changes always go via separate branch than DTS, so your patch
> breaks git bisect. I already pointed it out in other patch. This is not really
> acceptable. Breaking ABI is another problem which could be justified with
> your explanation in other cases... but not in this one, since it is easy to make
> it backwards compatible,

I see. But the current binding and dts using one clk is really wrong. Anyway,
I could make it backwards compatible.

Thanks,
Peng.
> 
> > Should I use a fixes tag to dt-bindings, then break ABI is allowed?
> 
> No. For such patch ABI break is also not allowed in that case. Just make the
> driver backwards compatible and both problems - non bisectability and ABI
> break - go away.
> 
> Best regards,
> Krzysztof