Re: [PATCH] mmc: enable UHS voltage switch for SDSC if supported【请注意，邮件由linux-mmc-owner@vger.kernel.org代发】

["Christian Löhle" <CLoehle@hyperstone.com>]

As I said I do not own this particular Goodram 2GB pSLC device,
but the product information sheet perfectly illustrates my point:
https://www.tme.eu/Document/73dbc1221619c627c52bf8dd35859e55/pSLC%20SD%20industrial%20Gold-Diamond.EN.pdf
(Page 10)
They claim up to 90MB/s for everything SDHC, but for 2GB they only
claim 20MB/s and Non-UHS mode.
So if the firmware was not specifically built without reporting any UHS
support, just for the 2GB version.
But there are quite some SLC devices with 2GB that claim over 25MB/s,
without mentioning UHS-I specifically. But clearly, either they are lying,
or have this non-standard SDSC UHS support.

From: Shawn Lin <shawn.lin@rock-chips.com>
Sent: Friday, April 23, 2021 8:51 AM
To: Christian Löhle <CLoehle@hyperstone.com>
Cc: shawn.lin@rock-chips.com <shawn.lin@rock-chips.com>; pali@kernel.org <pali@kernel.org>; huyue2@yulong.com <huyue2@yulong.com>; tiantao6@hisilicon.com <tiantao6@hisilicon.com>; linux-mmc@vger.kernel.org <linux-mmc@vger.kernel.org>; linux-kernel@vger.kernel.org <linux-kernel@vger.kernel.org>; ulf.hansson@linaro.org <ulf.hansson@linaro.org>
Subject: Re: [PATCH] mmc: enable UHS voltage switch for SDSC if supported【请注意，邮件由linux-mmc-owner@vger.kernel.org代发】 
 
On 2021/4/23 14:38, Christian Löhle wrote:
> Claiming UHS-I support with SDSC is pretty rare, for obvious reasons (namely they are non-standard, so it's a gamble if a host makes use of it), but here you go:
> https://de.rs-online.com/web/p/micro-sd-karten/8743910/
> (sorry for the german, the site has a en. subpage, but it's certificate seem untrusted.)
> The more likely case is that they do not advertise UHS-I to customers,
> but the card will show support to the host.
> Let's look at this product, just as an example.
> https://www.tme.eu/html/EN/goodram-industrial-industrial-sd-sd-micro-memory-cards/ramka_15242_EN_pelny.html
> They provide an MLC and pSLC version of each device, with half the capacity naturally.
> The 4GB MLC claims UHS-I support, the 2GB pSLC is very likely to be the same controller,
> it only claims Class 6.
> So either they specifically changed the firmware to remove any UHS support indication,
> or, more likely IMO, the card still reports UHS support to the host.
> Such a card would benefit from this patch.
> 
> Disclaimer: I do not own the product and have not confirmed this device in any way,
> but I have seen UHS support on other devices that do not advertise it for their
> SDSC versions.
> If the mailing list would be interested, I can try to acquire such devices, listed in
> public open stores. Modern, potentially UHS supporting cards. are,
> as mentioned in the initial Mail, often SLC or pSLC and often are made on
> a customers request.
> 
> 

Thanks for sharing these, but from the datasheets, these SDSC cards
claims their throught up to 20MB/s. So, I guess highpseed mode is enough
for them? what do you think?

Hyperstone GmbH | Line-Eid-Strasse 3 | 78467 Konstanz
Managing Directors: Dr. Jan Peter Berns.
Commercial register of local courts: Freiburg HRB381782