Quoting Doug Anderson (2022-05-02 18:06:39) > Hi, > > On Mon, May 2, 2022 at 3:02 PM Stephen Boyd <swboyd@xxxxxxxxxxxx> wrote: > > > > Quoting Doug Anderson (2022-05-02 10:02:54) > > > On Fri, Apr 29, 2022 at 4:31 PM Stephen Boyd <swboyd@xxxxxxxxxxxx> wrote: > > > > > > > > > > > > diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c > > > > index eef909e52e23..1bbe2987bf52 100644 > > > > --- a/drivers/input/keyboard/cros_ec_keyb.c > > > > +++ b/drivers/input/keyboard/cros_ec_keyb.c > > > > @@ -536,6 +536,12 @@ static int cros_ec_keyb_register_matrix(struct cros_ec_keyb *ckdev) > > > > u32 *physmap; > > > > u32 key_pos; > > > > unsigned int row, col, scancode, n_physmap; > > > > + bool register_keyboard; > > > > + > > > > + /* Skip matrix registration if no keyboard */ > > > > + register_keyboard = device_get_match_data(dev); > > > > + if (!register_keyboard) > > > > + return 0; > > > > > > > > /* > > > > * No rows and columns? There isn't a matrix but maybe there are > > > > > > As per my comments in patch #1, I wonder if it makes sense to delete > > > the "No rows and columns?" logic and settle on the compatible as the > > > one true way to specify this. > > > > > > > Ok. My only concern is that means we have to check for both compatibles > > which is not really how DT compatible strings work. The compatible > > string usually finds the more specific compatible that is first in the > > list of compatibles in DT. You're essentially proposing that the > > switches compatible could be first or last, the order doesn't matter. > > It's not quite what I was proposing. I think my summary really sums it up: Alright, I'm glad I misunderstood. > > 1. If you have a matrix keyboard and maybe also some buttons/switches > then use the compatible: google,cros-ec-keyb > > 2. If you only have buttons/switches but you want to be compatible > with the old driver in Linux that looked for the compatible > "google,cros-ec-keyb" and required the matrix properties, use the > compatible: "google,cros-ec-keyb-switches", "google,cros-ec-keyb" > > 3. If you have only buttons/switches and don't need compatibility with > old Linux drivers, use the compatible: "google,cros-ec-keyb-switches" > > ...but just to say it another way: > > * If you have the compatible "google,cros-ec-keyb-switches" I mean to > say that you _only_ have switches and buttons. You'd _never_ have this > compatible string if you truly have a matrix keyboard. If you have > this, it will always be first. > > * If you only have switches and buttons but you care about backward > compatibility then you can add a fallback compatible second: > "google,cros-ec-keyb" > > * In order for the fallback compatible to be at all useful as a > fallback (it's only useful at all if you're on an old driver), if you > specify it you should pretend that you have matrix properties even > though you don't really have them, just like we used to do. > Another important point is that the matrix properties are willfully ignored by the new driver if the "google,cros-ec-keyb-switches" compatible is present. Maybe it should be "google,cros-ec-no-keyb" to describe the true intent, i.e. ignore the keyboard properties. Or "google,cros-ec-keyboardless". I think it's confusing that I put "switches" in the compatible. It really should be about not registering the keyboard input device. Anyway, I agree that we don't need to use the matrix keyboard properties to figure out what to do. In fact, it isn't possible to remove the properties if "google,cros-ec-keyb" is present, so checking for them is redundant.
