Hi Linus, All, On Thu, 2021-03-25 at 12:32 +0200, Matti Vaittinen wrote: > On Thu, 2021-03-25 at 10:35 +0100, Linus Walleij wrote: snip > > It could potentially (like the other Rohm GPIO MFD PMIC drivers) > > make some use of the gpio regmap library, but we have some > > pending changes for that so look into it after the next merge > > window. > > > > I.e. for your TODO: look at the GPIO_REGMAP helper. > > I just took a quick peek at gpio_regmap and it looks pretty good to > me! > > Any particular reason why gpio_regmap is not just part of gpio_chip? > I > guess providing the 'gpio_regmap_direction_*()', 'gpio_regmap_get()', > 'gpio_regmap_set()' as exported helpers and leaving calling the > (devm_)gpiochip_add_data() to IC driver would have allowed more > flexibility. Drivers could then use the gpio_regamap features which > fit > the IC (by providing pointers to helper functions in gpio_chip) - and > handle potential oddball-features by using pointers to some > customized > functions in gpio_chip. So, v5.13-rc1 is out. I started wondering the gpio_regamap - and same question persists. Why hiding the gpio_chip from gpio_regmap users? Current IF makes it very hard (impossible?) for driver to override any of the regmap_gpio functions (or provide own alternatives) for cases which do not fit the generic regmap_gpio model. My first obstacle is providing gpio_chip.set_config for BD71815. 1) I guess the method fitting current design would be adding drive-mode register/mask(s) to the gpio_regmap_config. Certainly doable - but I have a bad feeling of this approach. I am afraid this leads to bloating the gpio_regmap_config with all kinds of IC specific workarounds (when HW designers have invented new cool control registers setups) - or then just not using the regmap_gpio for any ICs which have any quirks - even if 90% of regmap_gpio logic would fit... 2) Other possibility is allowing IC driver to provide function pointers for some operations (in my case for example for the set_config) - if the default operation the regmap_gpio provides does not fit the IC. This would require the regmap_gpio to be visible to IC drivers so that IC drivers can access the regmap, device & register information - or some way to convert the gpio_chip pointer to IC specific private data pointer. Doable but still slightly bloat. 3) The last option would be adding pointer to regmap_gpio to gpio_chip - and exporting the regmap_gpio functions as helpers - leaving the gpio registration to be done by the IC driver. That would allow IC driver to use the regmap_gpio helpers which suit the IC and write own functions for rest of the stuff. I'd like to hear opinions - should I draft some changes according to these proposals (which one, 1,2,3 or something else?) - or as this all been already discussed and am I just missing something? Best Regards Matti Vaittinen
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