On 8 December 2015 at 17:34, Daniel Lenski <dlenski@xxxxxxxxx> wrote: > On Dec 8, 2015 6:11 AM, "Ulf Hansson" <ulf.hansson@xxxxxxxxxx> wrote: >> >> On 4 December 2015 at 21:34, Daniel Lenski <dlenski@xxxxxxxxx> wrote: >> > In conclusion... it seems that the kernel is attempting to drive this >> > card faster than it can actually work. What I'm trying to figure out >> > now: >> > - How does the kernel attempt to figure out the capability of a given >> > SD card? Where is that in the kernel source tree? >> >> drivers/mmc/core/* >> >> It's kind of complicated, but please go ahead and have a look. > > Will do. > >> > - Is it possible to make the list of supported caps a module >> > parameter, to more easily throttle high-speed modes that don't work >> > with a particular card? >> >> Maybe a sysfs/debugfs interface would be better, but I like the idea! >> >> Currently there is no way for userspace to disable some of these >> "speed mode" caps, which would be very useful in cases like yours. >> >> I don't know if I ever will get time to hack on such code, so feel >> free to have a try yourself! > > Ideally, would it be better to have a userspace control at the level of the > individual host control drivers, or for the entire mmc/SD subsystem? I think per host controller would be the best. > >> Regarding how to fix this problem right now, I guess we should remove >> the caps which the host driver wrongly claims to support. Do you want >> to send a patch for that? > > I can do that, but am unsure whether it is truly an issue with the host > driver, or the card itself, in my case. > > Is there any information which I can use to clearly rule one or the other > case out? Well, you can try other SDHC cards and you may also try the failing card to see if it works with another host controller. > > If I understood Marcus Overhagen's original post correctly, he was > successful with a UHS SDHC card and this same controller. Okay. It may be that this card need some special treatment or that the UHS support for rtsx is fragile. > > Thanks, > Dan Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
