On Fri, Jun 21, 2013 at 11:17 PM, Stephen Warren <swarren@xxxxxxxxxxxxx> wrote: > When I pushed for the concept of groups, I intended it to mean precisely > one single thing. The points below describe this. > > 1) A pin is a single pin/ball/pad on the package. > > 2) Some register fields affect just a single pin. For example, there may > be a register field that affects pin A8's mux setting only. > > 3) Some register fields affect multiple pins at once. For example, > perhaps one register field affects both pin A8's an pin A7's mux setting > at once. > > 4) Depending on HW design, all register fields might be of type > described at (2) above, or all of the type described at (3) above, or a > mixture of both. Tegra is a mixture. > > 5) I expect the concept of a pin group to solely represent the various > groups of pins affected by each register field; in (2) above one pin per > group, in (3) above many pins per group. > > Thus, to my mind, a pin group is purely a HW concept, and dictated > purely by HW design. This we can discuss perpetually it seems. For Nomadik, as I've pointed out in the past it is actually: (6): it is one register/set if bits per pin, BUT the register settings pertain to physical lines having electrical settings which postulate that they be handled in batch or wreak havoc. I.e. it is a HW limitation in the *silicon* of *all* implementations, but that is *not* expressed in the register map. For the practical consequences see __nmk_config_pins if (glitch) runpath. Handling this as a group makes perfect sense from a hardware point of view. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
