On Tue, Nov 12, 2019 at 02:04:16PM +0100, Daniel Vetter wrote: > Wut ... Maybe I'm missing something, but from how we use mtrr in other > gpu drivers it's a) either you use MTRR because that's all you got or > b) you use pat. Mixing both sounds like a pretty bad idea, since if > you need MTRR for performance (because you dont have PAT) then you > can't fix the wc with the PAT-based ioremap_uc. And if you have PAT, > then you don't really need an MTRR to get wc. > > So I'd revert this patch from Luis and ... Sounds great to me.. > ... apply this one. Since the same reasoning should apply to anything > that's running on any cpu with PAT. Can you take a look at "mfd: intel-lpss: Use devm_ioremap_uc for MMIO" in linux-next, which also looks rather fishy to me? Can't we use the MTRR APIs to override the broken BIOS MTRR setup there as well? With that we could kill ioremap_uc entirely.
