Re: [PATCH V2] rtc: mc146818: Dont test for bit 0-5 in Register D

On Mon, Feb 01 2021 at 11:32, Linus Torvalds wrote:

On Mon, Feb 1, 2021 at 11:24 AM Thomas Gleixner [off-list ref] wrote:

quoted

While it cures the problem on the reporters machine it breaks machines
with Intel chipsets which use bit 0-5 of the D register. So check only
for bit 6 being 0 which is the case on these Intel machines as well.

This looks fine, but it might also be worth it simply just checking
for the only really special value: 0xff, and going "ok, that looks
like missing hardware".

That's what a few other drivers historically do in their probing
routines, so it's not unheard of (ie you can find drivers doing that
kind of

        /* If we read 0xff from the LSR, there is no UART here. */
        if (inb(.. port ..) == 0xff)

in their init routines.

Not a big deal either way, I just think it would be more in like with
what other places do in similar situations

Yeah, we can do that as well. Either way is fine.

Thanks,

        tglx