On Tue, Apr 28, 2020 at 10:37:43AM +0300, Grygorii Strashko wrote: > > > On 28/04/2020 02:31, Drew Fustini wrote: > > Add gpio-line-names properties to the gpio controller nodes. The names > > correspond to the AM335x pin names which are also the muxmode 0 signal > > names. Refer to "Table 4-2. Pin Attributes" in the TI AM335x Sitara > > Processors datasheet: > This misuse GPIO DT bindings: > " > Optionally, a GPIO controller may have a "gpio-line-names" property. This is > an array of strings defining the names of the GPIO lines going out of the > GPIO controller. This name should be the most meaningful producer name > for the system, such as a rail name indicating the usage. Package names > such as pin name are discouraged: such lines have opaque names (since they > are by definition generic purpose) and such names are usually not very > helpful. For example "MMC-CD", "Red LED Vdd" and "ethernet reset" are > reasonable line names as they describe what the line is used for. "GPIO0" > is not a good name to give to a GPIO line. Placeholders are discouraged: > rather use the "" (blank string) if the use of the GPIO line is undefined > in your design. The names are assigned starting from line offset 0 from > left to right from the passed array. An incomplete array (where the number > of passed named are less than ngpios) will still be used up until the last > provided valid line index. > " Thank you for pointing out that "Package names such as pin name are discouraged". That is what I was doing in that patch which I now realize is incorrect. The goal to adding the gpio-line-names was to have gpioinfo provide helpful information to a user on the BeagleBone. Currently this is all that appears when booting 5.7-rc2 on a BegaleBone: debian@beaglebone:~$ gpioinfo gpiochip0 - 32 lines: line 0: unnamed unused input active-high line 1: unnamed unused input active-high line 2: unnamed unused input active-high line 3: unnamed unused input active-high line 4: unnamed unused input active-high line 5: unnamed unused input active-high line 6: unnamed "cd" input active-low [used] line 7: unnamed unused input active-high line 8: unnamed unused input active-high line 9: unnamed unused input active-high line 10: unnamed unused input active-high line 11: unnamed unused input active-high line 12: unnamed unused input active-high line 13: unnamed unused input active-high line 14: unnamed unused input active-high line 15: unnamed unused input active-high line 16: unnamed unused input active-high line 17: unnamed unused input active-high line 18: unnamed unused input active-high line 19: unnamed unused input active-high line 20: unnamed unused input active-high line 21: unnamed unused input active-high line 22: unnamed unused input active-high line 23: unnamed unused input active-high line 24: unnamed unused input active-high line 25: unnamed unused input active-high line 26: unnamed unused input active-high line 27: unnamed unused input active-high line 28: unnamed unused input active-high line 29: unnamed unused input active-high line 30: unnamed unused input active-high line 31: unnamed unused input active-high gpiochip1 - 32 lines: line 0: unnamed unused input active-high line 1: unnamed unused input active-high line 2: unnamed unused input active-high line 3: unnamed unused input active-high line 4: unnamed unused input active-high line 5: unnamed unused input active-high line 6: unnamed unused input active-high line 7: unnamed unused input active-high line 8: unnamed unused input active-high line 9: unnamed unused input active-high line 10: unnamed unused input active-high line 11: unnamed unused input active-high line 12: unnamed unused input active-high line 13: unnamed unused input active-high line 14: unnamed unused input active-high line 15: unnamed unused input active-high line 16: unnamed unused input active-high line 17: unnamed unused input active-high line 18: unnamed unused input active-high line 19: unnamed unused input active-high line 20: unnamed unused input active-high line 21: unnamed "beaglebone:green:usr0" output active-high [used] line 22: unnamed "beaglebone:green:usr1" output active-high [used] line 23: unnamed "beaglebone:green:usr2" output active-high [used] line 24: unnamed "beaglebone:green:usr3" output active-high [used] line 25: unnamed unused input active-high line 26: unnamed unused input active-high line 27: unnamed unused input active-high line 28: unnamed unused input active-high line 29: unnamed unused input active-high line 30: unnamed unused input active-high line 31: unnamed unused input active-high gpiochip2 - 32 lines: line 0: unnamed unused input active-high line 1: unnamed unused input active-high line 2: unnamed unused input active-high line 3: unnamed unused input active-high line 4: unnamed unused input active-high line 5: unnamed unused input active-high line 6: unnamed unused input active-high line 7: unnamed unused input active-high line 8: unnamed unused input active-high line 9: unnamed unused input active-high line 10: unnamed unused input active-high line 11: unnamed unused input active-high line 12: unnamed unused input active-high line 13: unnamed unused input active-high line 14: unnamed unused input active-high line 15: unnamed unused input active-high line 16: unnamed unused input active-high line 17: unnamed unused input active-high line 18: unnamed unused input active-high line 19: unnamed unused input active-high line 20: unnamed unused input active-high line 21: unnamed unused input active-high line 22: unnamed unused input active-high line 23: unnamed unused input active-high line 24: unnamed unused input active-high line 25: unnamed unused input active-high line 26: unnamed unused input active-high line 27: unnamed unused input active-high line 28: unnamed unused input active-high line 29: unnamed unused input active-high line 30: unnamed unused input active-high line 31: unnamed unused input active-high gpiochip3 - 32 lines: line 0: unnamed unused input active-high line 1: unnamed unused input active-high line 2: unnamed unused input active-high line 3: unnamed unused input active-high line 4: unnamed unused input active-high line 5: unnamed unused input active-high line 6: unnamed unused input active-high line 7: unnamed unused input active-high line 8: unnamed unused input active-high line 9: unnamed unused input active-high line 10: unnamed unused input active-high line 11: unnamed unused input active-high line 12: unnamed unused input active-high line 13: unnamed unused input active-high line 14: unnamed unused input active-high line 15: unnamed unused input active-high line 16: unnamed unused input active-high line 17: unnamed unused input active-high line 18: unnamed unused input active-high line 19: unnamed unused input active-high line 20: unnamed unused input active-high line 21: unnamed unused input active-high line 22: unnamed unused input active-high line 23: unnamed unused input active-high line 24: unnamed unused input active-high line 25: unnamed unused input active-high line 26: unnamed unused input active-high line 27: unnamed unused input active-high line 28: unnamed unused input active-high line 29: unnamed unused input active-high line 30: unnamed unused input active-high line 31: unnamed unused input active-high I discussed it with Robert Nelson and Jason Kridner and the idea came up that using the beagle pin header labels would be more useful than the AM3358 pin names. > Additional note. On other TI SoCs like am437x the same gpio line can be routed to more > than one pin (but only one pin can be used). > gpio0_0 GPIO IO -> A17, D16 Thank you for that insights. Instead of am33xx-l4.dtsi, I am thinking of adding a gpio-line-names property in: source/arch/arm/boot/dts/am335x-bone-common.dtsi For gpiochip0, line 0 and line 1 would be "" as they are not connected to P8/P9 header. line 2 would be labeled "P9_22", line 3 would be "P9_21", etc. I'll post a complete patch for am335x-bone-common.dtsi and the gpioinfo output to demonstrate the usefulness. thanks, drew
