On Wed, 5 May 2021 at 14:13, Christian Löhle <CLoehle@xxxxxxxxxxxxxx> wrote: > > So two cards that advertise UHS: > https://www.euric.de/de/flash-speicher/sd-microsd/sd/ > Model SDI790 > and > https://na.industrial.panasonic.com/products/storage-media/industrial-sd-cards/lineup/industrial-grade-2d-nand/series/71695 Thanks for the links! Are these the ones that you have been using for testing? > Hopefully that suffices as a couple, otherwise I would buy some > that do not advertise it and actually check if they support it anyway. > But 2GB SLC listings are kind of rare these days, so it's not as > easy to find many that are still sold and available. Right. I have a whole bunch of old SD cards that I can test. I will let you know when I have got some time to test some of them. The main worry (but I may be wrong) I have with the patch is that it could cause problems for other older SDSC cards, which happens to incorrectly set the S18A bit. I mean, before UHS-I was introduced in the SD spec, this bit was just being reserved and potentially it could have *any* value by the card manufacturer. As I said, let me do some tests of my older SD cards. > > My point about deviating from the standard was that these cards > are already initialized as UHS, they just don't do the voltage switch. > So anything reserved for UHS-I (e.g. CMD23 )is already being done > by the host with the current linux-mmc, > so the standard deviation is already there. > Just the voltage switch is missing. Ah, yes you are right! We call mmc_sd_init_uhs_card() no matter whether the CCS bit is set. Certainly this is a bug. Both the card and host aren't designed to work under these conditions/timings. > > Regards, > Christian > Kind regards Uffe > > From: Ulf Hansson <ulf.hansson@xxxxxxxxxx> > Sent: Wednesday, May 5, 2021 12:09 PM > To: Christian Löhle <CLoehle@xxxxxxxxxxxxxx> > Subject: Re: [PATCH] mmc: enable UHS voltage switch for SDSC if supported > > On Thu, 22 Apr 2021 at 15:18, Christian Löhle <CLoehle@xxxxxxxxxxxxxx> wrote: > > > > Ignore the reported capacity if the card otherwise reports UHS support. > > > > Currently SDSC cards reporting UHS support except for the CCS do not run > > through the voltage switch. > > While strictly speaking a SDSC card cannot support UHS in compliance > > with the standard, there is no good reason to throttle them that way. > > Maybe not, but I think the code just tries to conform to the SD spec. > > > Especially for pSLCs in practice such cards benefit greatly by this patch, > > as they can be new and UHS supporting, but must not lie about their CCS. > > Can you provide some concrete examples of SDSC cards that support UHS-I? > > > The behaviour of linux-mmc for SDSC is deviating from the standard anyway > > in such a case, as the card is treated as UHS card not supporting the > > voltage switch in general. > > Such a card will come up as > > mmc0: new ultra high speed SDR25 SD card at address 0001. > > Thus the subsystem will support CMD23 and others to the card. > > But if we deviate from the standard anyway, then we might as well > > not throttle SDSC to 25MB/s. > > Not sure I understand this correctly? Can you elaborate a bit more, so > I understand how we deviate from the SD spec here? > > As far as I understand the spec, SDSC cards shouldn't support UHS-I. > If we decide to deviate from the spec to support this anyway, at least > we need to know about a couple of cards that actually supports this. > > Kind regards > Uffe > > > > > Signed-off-by: Christian Loehle <cloehle@xxxxxxxxxxxxxx> > > --- > > drivers/mmc/core/sd.c | 7 +++---- > > 1 file changed, 3 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c > > index 6fa51a6ed058..281ca2da8e0b 100644 > > --- a/drivers/mmc/core/sd.c > > +++ b/drivers/mmc/core/sd.c > > @@ -841,11 +841,10 @@ int mmc_sd_get_cid(struct mmc_host *host, u32 ocr, u32 *cid, u32 *rocr) > > return err; > > > > /* > > - * In case CCS and S18A in the response is set, start Signal Voltage > > - * Switch procedure. SPI mode doesn't support CMD11. > > + * In case S18A in the response is set, start Signal Voltage Switch > > + * procedure. SPI mode doesn't support CMD11. > > */ > > - if (!mmc_host_is_spi(host) && rocr && > > - ((*rocr & 0x41000000) == 0x41000000)) { > > + if (!mmc_host_is_spi(host) && rocr && (*rocr & 0x01000000)) { > > err = mmc_set_uhs_voltage(host, pocr); > > if (err == -EAGAIN) { > > retries--; > > -- > > 2.31.1 > > > > Hyperstone GmbH | Line-Eid-Strasse 3 | 78467 Konstanz > > Managing Directors: Dr. Jan Peter Berns. > > Commercial register of local courts: Freiburg HRB381782 > > > > Hyperstone GmbH | Line-Eid-Strasse 3 | 78467 Konstanz > Managing Directors: Dr. Jan Peter Berns. > Commercial register of local courts: Freiburg HRB381782 >
