On 4/4/23 16:05, Linus Walleij wrote: > On Mon, Apr 3, 2023 at 1:41 PM Edmund Berenson > <edmund.berenson@xxxxxxxxx> wrote: > >> Add driver for maxim MAX7317 SPI-Interfaced 10 Port >> GPIO Expander. >> >> v2: adjust driver to use regmap >> >> Co-developed-by: Lukasz Zemla <Lukasz.Zemla@xxxxxxxxxxxx> >> Signed-off-by: Lukasz Zemla <Lukasz.Zemla@xxxxxxxxxxxx> >> Signed-off-by: Edmund Berenson <edmund.berenson@xxxxxxxxx> > > Notwithstanding the other comments from Bartosz, this seems like > a driver that should be using the regmap GPIO helper library. > git grep GPIO_REGMAP will show you examples of other drivers > that use this and how it is used. > > Yours, > Linus Walleij Hi, thanks for the review and suggestion. I tried following your suggestion and use GPIO_REGMAP to implement the driver. Unfortunately I ran into two issues 1. reg_set_base == 0: for the devcie reg_set base is 0x0. In gpio-regmap there are several tests for !reg_set_base. There doesn't seem a way to distinguish between is set to 0 and is not set. :) 2. input/output direction: to set a gpio pin to input one has to write 0x1 to the corresponding output register. The issue starts when I configure a port to be an output, set output to 0x1, check the direction of the pin, doing so trough sysfs the system will now assume the pin is an input and I can't set its values anymore. Avoiding this I would like to track the direction of the pin separately from the device register, which is atm done in the corresponding bespoke in/out functions. I could probably solve both of these issues trough the reg_mask_xlate function but I believe this would introduce unneeded obscurity in the driver. I do not believe there are any other easy obvious/better fixes for this. (or maybe you prove me wrong :)) Would you be okay for this driver to stick with direct regmap usage? (obviously fixing the review suggestions) BR Edmund -- Edmund Berenson, emlix GmbH, http://www.emlix.com Fon +49 551 30664-0, Fax +49 551 30664-11 Gothaer Platz 3, 37083 Göttingen, Germany Sitz der Gesellschaft: Göttingen, Amtsgericht Göttingen HR B 3160 Geschäftsführung: Heike Jordan, Dr. Uwe Kracke – Ust-IdNr.: DE 205 198 055 emlix - smart embedded open source
