> On Sun, Nov 11, 2012 at 2:32 AM, Rob Herring <robherring2@xxxxxxxxx> > wrote: >> On 11/09/2012 06:48 PM, Stepan Moskovchenko wrote: >>> Use the cell-index property to construct names for platform >>> devices, falling back on the existing scheme of using the >>> device register address if cell-index is not specified. >>> >>> The cell-index property is a more useful device identifier, >>> especially in systems containing several numbered instances >>> of a particular hardware block, since it more easily >>> illustrates how devices relate to each other. >>> >>> Additionally, userspace software may rely on the classic >>> <name>.<id> naming scheme to access device attributes in >>> sysfs, without having to know the physical addresses of >>> that device on every platform the userspace software may >>> support. Using cell-index for device naming allows the >>> device addresses to be hidden from userspace and to be >>> exposed by logical device number without having to rely on >>> auxdata to perform name overrides. This allows userspace to >>> make assumptions about which sysfs nodes map to which >>> logical instance of a specific hardware block. >>> >>> Signed-off-by: Stepan Moskovchenko <stepanm@xxxxxxxxxxxxxx> >>> --- >>> I had also considered using something like the linux,label property to >>> allow >>> custom names for platform devices without resorting to auxdata, but the >>> cell-index approach seems more in line with what cell-index was >>> intended for >>> and with what the pre-DT platform device naming scheme used to be. >>> Please let >>> me know if you think there is a better way to accomplish this. >>> >>> This is just being sent out as an RFC for now. If there are no >>> objections, I >>> will send this out as an official patch, along with (or combined with) >>> a patch >>> to fix up the device names in things like clock tables of any affected >>> platforms. >> >> cell-index is basically deprecated. This has been discussed multiple >> times in the past. You can use auxdata if you really need to have the >> old name. > > Actually, I think it would be fine to use an /aliases entry to set the > device name. That's the place to put global namespace information. > > g. > Ah, thank you. I would prefer to stay away from auxdata, since it involves placing more platform-specific data into the kernel, and it is my understanding that auxdata is intended as a temporary measure. The /aliases approach looks interesting, and I'll see what I can do with it - hopefully I can have an RFC / patch soon. It looks like we would want an "inverse" alias lookup- that is, we would need to know which alias corresponds to a given node. Is it possible for a node to have multiple aliases? If so, which shall we use to create the device name? Anyway, I will further look into how these aliases work. Steve -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
