Hi all, On Fri, Jan 29, 2021 at 09:37:47PM +0100, Clemens Gruber wrote: > Hi Sven, > > On Fri, Jan 29, 2021 at 01:05:14PM -0500, Sven Van Asbroeck wrote: > > Hi Clemens, > > > > On Fri, Jan 29, 2021 at 11:31 AM Clemens Gruber > > <clemens.gru...@pqgruber.com> wrote: > > > > > > Ok, so you suggest we extend our get_state logic to deal with cases > > > like the following: > > > > Kind of. We can't control how other actors (bootloaders etc) program the > > chip. As far as I know, there are many, many different register settings > > that > > result in the same physical chip outputs. So if .probe() wants to preserve > > the > > existing chip settings, .get_state() has to be able to deal with every > > possible > > setting. Even invalid ones. > > Is the driver really responsible for bootloaders that program the chip > with invalid values? > The chip comes out of PoR with sane default values. If the bootloader of > a user messes them up, isn't that a bootloader problem instead of a > Linux kernel driver problem? > > > In addition, .apply() cannot make any assumptions as to which bits are > > already set/cleared on the chip. Including preserved, invalid settings. > > > > This might get quite complex. > > > > However if we reset the chip in .probe() to a known state (a normalized > > state, > > in the mathematical sense), then both .get_state() and .apply() become > > much simpler. because they only need to deal with known, normalized states. > > Yes, I agree. This would however make it impossible to do a flicker-free > transition from bootloader to kernel, but that's not really a usecase I > have so I can live without it. > > Another point in favor of resetting is that the driver already does it. > Removing the reset of the OFF register may break some boards who rely on > that behaviour. > My version only extended the reset to include the ON register. > > > > > In short, it's a tradeoff between code complexity, and user friendliness/ > > features. > > > > Sven > > Thierry, Uwe, what's your take on this? > > Thierry: Would you accept it if we continue to reset the registers in > .probe? > > Thanks, > Clemens
I realize that it is a difficult time at the moment, but it is a little bit frustrating not getting any response from the maintainer. I think the best way forward is to just keep the register resets in probe as they are. If this is to be changed, I think it should be done in a separate patchset and by someone who has a usecase requiring it. Best regards, Clemens
