Re: IMX6 ESDHC mmc with UHS-I occasional failure with DDR50 cards

[David Haworth <dave@fen-net.de>]

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Hi Tim,

This looks uncomfortably familiar.
I've been having problems with "some" micro-SDHC cards, but in
different circumstances: mmc_spi on a raspberry pi.

"Good" cards sign on as "mmcblk1: mmc1:0000 00000 7.35 GiB"
"Bad" cards sign on as  "mmcblk1: mmc1:0000 SU08G 7.40 GiB"
and eventually return a bit shifted response.

The "bad" cards are all SanDisk cards. The "good" cards are cheap
cards with one exception that is marked as SanDisk but looks like
a fake.

More details here:
https://www.raspberrypi.org/forums/viewtopic.php?f=44&t=172562&p=1103943#p1103943
if you can read it.
Unfortunately I don't have a solution.

All the best
Dave

On 2017-04-04 14:26:40 -0700, Tim Harvey wrote:
> Greetings,
> 
> I've been seeing mmc failures with Linux 4.10 on some IMX6 boards with
> UHS-I support when used with DDR50 cards (I've got a couple from
> different manufacturers). I do not see the same issues when using
> SDR104 cards. I can also see the issue on the latest linux-mmc repo.
> 
> The issue is easily replicated by ejecting and inserting the DDR50 card
> 
> A successful init looks like this:
> [  150.514018] mmc0: host does not support reading read-only switch,
> assuming write-enable
> [  150.578204] mmc0: new ultra high speed DDR50 SDHC card at address aaaa
> [  150.592140] mmcblk0: mmc0:aaaa SL08G 7.40 GiB
> [  150.611512]  mmcblk0: p1
> 
> A failing init (about 1 of every 5 trys) looks like this:
> [   49.514082] mmc0: host does not support reading read-only switch,
> assuming write-enable
> [   49.676112] mmc0: tuning execution failed: -5
> [   49.680510] mmc0: ddr50 tuning failed
> [   49.684206] mmc0: new ultra high speed DDR50 SDHC card at address aaaa
> [   49.696456] mmcblk0: mmc0:aaaa SL08G 7.40 GiB
> ^^^^ failed to read the partition table and at this point all access fails:
> # dd if=/dev/mmcblk0 of=/dev/null bs=1k count=1
> [   89.417210] mmcblk0: error -84 transferring data, sector 0, nr 32,
> cmd response 0x900, card status 0xb00
> 1+0 records in
> 1+0 records out
> 1024 bytes (1.0 kB, 1.0 KiB) copied, 0.1227 s, 8.3 kB/s
> 
> I know the issue started occurring in Linux v4.4 but I also have heard
> there are some tuning patches in the queue so before I bisected
> between v4.4 and v4.3. Note that v4.3 is missing DDR50 tuning but when
> I backport that I found that when ddr tuning failed there it did not
> cause the card to not be accessible.
> 
> Regards,
> 
> Tim
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