Re: [PATCH ath-next] ath9k: eeprom: alias vpdTableI onto vpdTableL to shrink stack frame

[Toke Høiland-Jørgensen]

"Rosen Penev" <rosenp@xxxxxxxxx> writes:

> On Thu Jun 18, 2026 at 2:51 AM PDT, Toke Høiland-Jørgensen wrote:
>> Rosen Penev <rosenp@xxxxxxxxx> writes:
>>
>>> vpdTableL, vpdTableR, and vpdTableI are never live simultaneously.
>>> vpdTableL and vpdTableR are consumed during the frequency-interpolation
>>> step that writes vpdTableI; after the if/else they are never read
>>> again.  Reuse vpdTableL for the interpolated result (what was
>>> vpdTableI), reducing the stack frame by one 256-byte array.
>>>
>>> The read-via-write in the else branch is safe: ath9k_hw_interpolate()
>>> receives vpdTableL[i][j] by value as a function argument before the
>>> return value is written back to vpdTableL[i][j].
>>>
>>> Stack frame size change (x86_64, clang):
>>>   before: 0x440 (1088 B)
>>>   after:  0x330 (816 B)
>>
>> Huh? These are static variables, how is this affecting stack usage?
>> I assume this is against your previous (broken) patch?
> It's only broken on ARM + GCC. GCC + anything else and Clang + anything
> else is fine.

That's still broken, though :)

>> Anyway, adding this kind of aliasing to fix a problem that you
>> introduced by changing working code with no real benefit is not an
>> improvement. I'm OK with fixing actual bugs, but this is just mindless
>> churn...
> Fixing actual bugs is the goal yes. It makes sense to split up into
> multiple parts IMO.

If you're fixing an actual bug, include that in the patch description,
and if it requires multiple patches include them in a series. Sending
these out of context patches that just shuffle code around is just
churn...

-Toke