Messages in this thread | | | Date | Wed, 16 Nov 2022 16:41:30 +0100 | From | Michael Walle <> | Subject | Re: [PATCH v2 1/4] gpio: regmap: Always set gpio_chip get_direction |
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Am 2022-11-13 14:21, schrieb William Breathitt Gray: > On Sun, Nov 13, 2022 at 02:40:17PM +0200, Andy Shevchenko wrote: >> On Thu, Nov 10, 2022 at 08:55:50PM -0500, William Breathitt Gray >> wrote: >> > If you only have reg_dat_base set, then it is input-only; if you only >> > have reg_set_base set, then it is output-only. Thus, we can always set >> > gpio_chip get_direction to gpio_regmap_get_direction and return >> > GPIO_LINE_DIRECTION_IN/GPIO_LINE_DIRECTION_OUT given the respective >> > register base addresses configuration. >> >> Seems legit to me. Have you checked if we have any gpio-regmap drivers >> that >> have something like this in their configuration already? In such cases >> we need >> to be sure they behave as expected. >> >> From the code perspective: >> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > I see gpio-sl28cpld has two device types SL28CPLD_GPO (output-only) and > SL28CPLD_GPI (input-only); gpio-tn48m similarly has two device types > TN48M_GPO (output-only) and TN48M_GPI (input-only). It doesn't look > like > the change in this patch will cause problems for them, but I'll let > Michael Walle and Robert Marko comment if they see issues here.
For the sl28cpld driver this shouldn't be a problem. So for that Acked-by: Michael Walle <michael@walle.cc>
But back when I wrote gpio-regmap the bgpio served as a blue print. There is the same handling. If you look at gpiolib-sysfs.c there is a comment about the direction property:
* MAY BE OMITTED if kernel won't allow direction changes
So from a gpiolib/sysfs POV I'm not sure about this change. Does get_direction == NULL means setting the direction isn't possible? OTHO there is a fat "MAY" :)
Which brings me to the question of "why this change?". The commit message doesn't mention it. Just out of curiosity.
-michael
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