* H. Nikolaus Schaller hns@goldelico.com [170326 22:22]:
Am 27.03.2017 um 04:18 schrieb Matthijs van Duin matthijsvanduin@gmail.com:
*sigh* okay I think I need to wake up properly first...
primary SD can switch signal voltage using LDO9. eMMC always uses 1.8V signalling and is speed-limited only by mux. μSD cannot switch signal voltage to 1.8V hence cannot support any UHS mode.
I just noticed that your kernel called eMMC "mmc0" instead of "mmc1", that's confusing as hell. Please apply: https://github.com/mvduin/linux/tree/patch/of-alias
Has this been suggested upstream?
I'd prefer to keep the number of such deviations from mainline core code as low as possible unless it is absolute necessary. This seems to be a patch which makes life a lot easier, but I have no problem using mmc0/1 names by using UUIDs at the right locations. And it should not be omap5 only because Letux supports other SoC as well (omap3/4/am335x). So either do it right and the same for all or don't.
Therefore I have also addressed Tony if such a patch is/can be being considered upstream.
Heheheh the use of aliases tends to get shot down as it's a device tree specific workaround, see for example this thread:
http://linux-kernel.2935.n7.nabble.com/PATCH-v2-0-4-Patches-to-allow-consist...
I guess you could try sending a patch for example against omap5-board-common.dtsi and Cc Rob Herring and devicetree lists. My guess is that use of aliases for this is still considered non-standard use of device tree aliases.
It is certainly unclear when aliases should be used though, but my understanding is that it's a device tree specific workaround to a Linux generic issue where UUIDs are solving it.
My guess is that the alias names for Pyra should be something like this instead:
"sdio1", "sdio2", "micro-sd"
Basically something that describes where the slots are on Pyra.
Trying to think of alternatives, we could possibly patch omap_hsmmc.c to produce readable dev_name(). But that probably requires address to name mapping table for various SoCs and that's not liked either.
Yeah the moving devices are a big pain. Don't even get me started on cheapo pl2303 USB dongles with no serial number..
Regards,
Tony