On 1/11/22 8:54 AM, Andy Shevchenko wrote: > On Tue, Jan 11, 2022 at 4:53 PM Andy Shevchenko > <andy.shevchenko@xxxxxxxxx> wrote: >> On Tue, Jan 11, 2022 at 4:13 PM Terry Bowman <Terry.Bowman@xxxxxxx> wrote: >>> The cd6h/cd7h port I/O can be disabled on recent AMD processors and these >>> changes replace the cd6h/cd7h port I/O accesses with with MMIO accesses. >>> I can provide more details or answer questions. >> >> AFAIU the issue the list of questions looks like this (correct me, if >> I'm wrong): >> - some chips switched from I/O to MMIO >> - the bus driver has shared resources with another (TCO) driver >> Correct >> Now, technically what you are trying is to find a way to keep the >> original functionality on old machines and support new ones without >> much trouble. >> >> From what I see, the silver bullet may be the switch to regmap as we >> have done in I2C DesignWare driver implementation. >> >> Yes, it's a much more invasive solution, but at the same time it's >> much cleaner from my p.o.v. And you may easily split it to logical >> parts (prepare drivers, switch to regmap, add a new functionality). >> >> I might be missing something and above not gonna work, please tell me >> what I miss in that case. > > On top of that I'm wondering why slow I/O is used? Do we have anything > that really needs that or is it simply a cargo-cult? The efch SMBUS & WDT previously only supported a port I/O interface (until recently) and thus dictated the HW access method. Wolfram pointed out some AMD laptops suffer from slow trackpad [1] and this is part of the fix. [1] https://lore.kernel.org/r/CAPoEpV0ZSidL6aMXvB6LN1uS-3CUHS4ggT8RwFgmkzzCiYJ-XQ@xxxxxxxxxxxxxx > >>> On 1/11/22 6:39 AM, Wolfram Sang wrote: >>>> >>>>> I have briefly read the discussion by the link you provided above in >>>>> this thread. I'm not sure I understand the issue and if Intel hardware >>>>> is affected. Is there any summary of the problem? >>>> >>>> I guess the original patch description should explain it. You can find >>>> it here: >>>> >>>> https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fpatchwork.ozlabs.org%2Fproject%2Flinux-i2c%2Fpatch%2F20210715221828.244536-1-Terry.Bowman%40amd.com%2F&data=04%7C01%7CTerry.Bowman%40amd.com%7C89e551e0ebe94607beaf08d9d51288f9%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637775097863907004%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=gvJ0FC9MVacQunc8uMJ6oJEw0pGcisu9muQkE8u4rxY%3D&reserved=0 >>>> >>>> If this is not sufficient, hopefully Terry can provide more information? >
