On Wed, Dec 19, 2018 at 7:22 PM Trent Piepho <tpiepho@xxxxxxxxxx> wrote: > > On Wed, 2018-12-19 at 16:47 -0800, Andrey Smirnov wrote: > > > > > > This series initially added explicit offsets but I suggested a single > > > > "controller-id" because: > > > > * There are multiple bit and byte offsets > > > > * Other imx8 SOCs also have 2x pcie with other bit/byte offsets > > > > > > > > Hiding this behind a compatible string and single "controller-id" seem > > > > preferable to elaborating register maps in dt bindings. It also makes > > > > upgrades simpler: if features are added which use other bits there is no > > > > need to describe them in DT and deal with compatibility headaches. > > > > > > You already have an id for the controllers: the address. Use that if > > > you don't want to put the register offsets in DT. > > > > > > > Lucas, are you on board with this? > > Does address here mean the address from the controller's reg property? Yes. > How do you map that address to the controller's index? A giant table > of every soc so the soc type plus controller register address pair than > can be looked up in the driver? You only need the 2-Nth instance addresses. A non-matching address can be instance 0. > I.e., on iMX8MQ the controller at 0x33800000 is controller 0 and so on > for every possible SoC address combination? > > Not really a fan of that. Well, this was not my first suggestion. > The situation here is that some registers for these controllers are > interleaved, right? I.e., there's one register somewhere where bit 0 > means enable controller 0 and bit 1 means enable controller 1 and so > on. So? The only difference here is an additional mapping step. > Isn't cell-index already the standard device tree property for this > kind of setup? > > I know cell-index was historically also (ab)used in an attempt to > provide a fixed kernel device enumeration order, something now handled > better by chosen node aliases. Don't use cell-index. Consider it a deprecated relic from OF that is not used on FDT (though there probably are some cases it did get used). Rob
