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
>
