On Tue, Jan 19, 2021 at 10:10 AM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > > Hi Saravana, > > On Tue, Jan 19, 2021 at 6:54 PM Saravana Kannan <saravanak@xxxxxxxxxx> wrote: > > On Tue, Jan 19, 2021 at 2:20 AM Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: > > > On Tue, Jan 19, 2021 at 9:50 AM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > > > > > Can we pull this into driver-core-next please? It fixes issues on some > > > > > boards with fw_devlink=on. > > > > > > > > On r8a77951-salvator-xs.dts, it introduces one more failure: > > > > > > > > OF: /soc/i2c@e66d8000/gpio@20/pcie-sata-switch-hog: could not get > > > > #gpio-cells for /cpus/cpu@102 > > > > Geert, > > > > One good thing is that it's noticing this being weird and ignoring it > > in your particular board. I *think* it interprets the "7" as a phandle > > and that's cpu@102 and realizes it's not a gpio-controller. For at > > least in your case, it's a safe failure. > > While 7 is the GPIO index, relative to the current GPIO controller, > represented by the parent device node. > > > > > Seems like it doesn't parse gpios properties in GPIO hogs correctly. > > > > > > Could it be that the code assumes no self-referencing phandles? > > > (Just guessing...) > > > > Ok I tried to understand what gpio-hogs means. It's not fully clear to > > me. But it looks like if a gpio-controller has a gpio-hog, then it > > doesn't have/need gpio-cells? Is that right? > > A GPIO hog is a way to fix (strap) a GPIO line to a specific value. > Usually this is done to enable a piece of hardware on a board, or > control a mux. > > The controller still needs gpio-cells. > > > So if a gpio-controller has a gpio-hog, can it ever be referred to by > > another consumer in DT using blah-gpios = ...? If so, I don't see any > > obvious code that's handling the missing gpio-cells in this case. > > Yes it can. > > > Long story short, please help me understand gpio-hog in the context of > > finding dependencies in DT. > > The hog references a GPIO on the current controller. As this is always > the parent device node, the hog's gpios properties lack the phandle. > > E.g. a normal reference to the first GPIO of gpio5 looks like: > > gpios = <&gpio5 0 GPIO_ACTIVE_LOW>; > > A hog on the first GPIO of gpio5 would be a subnode of gpio5, > and would just use: > > gpios = <0 GPIO_ACTIVE_LOW>; > > instead. > > Hope this helps. I'm still not sure if I've understood this fully, but does this just boil down to: Don't parse [name-]gpio[s] to find dependencies if the node has gpio-hog property? -Saravana
