random mmc error

[javiermarto]

Every once in a while we are starting our custom board and we are getting this panic (mmcblk0: error -84 transferring data...) reading the EMMC memory, any idea of what could be?

[    2.091481] Waiting for root device /dev/mmcblk0p2...

[    2.124622] mmc1: new DDR MMC card at address 0001

[    2.130853] mmcblk0: mmc1:0001 SEM08G 7.39 GiB

[    2.135739] mmcblk0boot0: mmc1:0001 SEM08G partition 1 1.00 MiB

[    2.141926] mmcblk0boot1: mmc1:0001 SEM08G partition 2 1.00 MiB

[    2.148078] mmcblk0rpmb: mmc1:0001 SEM08G partition 3 128 KiB

[    2.160665] mmcblk0: error -84 transferring data, sector 0, nr 8, cmd response 0x900, card status 0xb00

[    2.170093] mmcblk0: retrying using single block read

[    2.175813] mmcblk0: error -84 transferring data, sector 0, nr 8, cmd response 0x900, card status 0x0

[    2.185118] blk_update_request: I/O error, dev mmcblk0, sector 0

[    2.192554] mmcblk0: error -84 transferring data, sector 1, nr 7, cmd response 0x900, card status 0x0

[    2.201820] blk_update_request: I/O error, dev mmcblk0, sector 1

[    2.208486] mmcblk0: error -84 transferring data, sector 2, nr 6, cmd response 0x900, card status 0x0

[    2.217744] blk_update_request: I/O error, dev mmcblk0, sector 2

[    2.224426] mmcblk0: error -84 transferring data, sector 3, nr 5, cmd response 0x900, card status 0x0

[    2.233683] blk_update_request: I/O error, dev mmcblk0, sector 3

[    2.240334] mmcblk0: error -84 transferring data, sector 4, nr 4, cmd response 0x900, card status 0x0

[    2.249594] blk_update_request: I/O error, dev mmcblk0, sector 4

[    2.256276] mmcblk0: error -84 transferring data, sector 5, nr 3, cmd response 0x900, card status 0x0

[    2.265533] blk_update_request: I/O error, dev mmcblk0, sector 5

[    2.272198] mmcblk0: error -84 transferring data, sector 6, nr 2, cmd response 0x900, card status 0x0

[    2.281431] blk_update_request: I/O error, dev mmcblk0, sector 6

[    2.288133] mmcblk0: error -84 transferring data, sector 7, nr 1, cmd response 0x900, card status 0x0

[    2.297398] blk_update_request: I/O error, dev mmcblk0, sector 7

[    2.303607] Buffer I/O error on dev mmcblk0, logical block 0, async page read

[    2.311805] mmcblk0: error -84 transferring data, sector 0, nr 8, cmd response 0x900, card status 0xb00

[    2.321205] mmcblk0: retrying using single block read

[    2.326917] mmcblk0: error -84 transferring data, sector 0, nr 8, cmd response 0x900, card status 0x0

[    2.336166] blk_update_request: I/O error, dev mmcblk0, sector 0

[    2.342823] mmcblk0: error -84 transferring data, sector 1, nr 7, cmd response 0x900, card status 0x0

[    2.352071] blk_update_request: I/O error, dev mmcblk0, sector 1

[    2.358705] mmcblk0: error -84 transferring data, sector 2, nr 6, cmd response 0x900, card status 0x0

[    2.368582] mmcblk0: error -84 transferring data, sector 3, nr 5, cmd response 0x900, card status 0x0

[    2.378457] mmcblk0: error -84 transferring data, sector 4, nr 4, cmd response 0x900, card status 0x0

[    2.388336] mmcblk0: error -84 transferring data, sector 5, nr 3, cmd response 0x900, card status 0x0

[    2.398203] mmcblk0: error -84 transferring data, sector 6, nr 2, cmd response 0x900, card status 0x0

[    2.408137] mmcblk0: error -84 transferring data, sector 7, nr 1, cmd response 0x900, card status 0x0

[    2.417390] Buffer I/O error on dev mmcblk0, logical block 0, async page read

[    2.424706]  mmcblk0: unable to read partition table

[    2.542241] VFS: Cannot open root device "mmcblk0p2" or unknown-block(179,2): error -6

[    2.550165] Please append a correct "root=" boot option; here are the available partitions:

[    2.558638] b300         7757824 mmcblk0  driver: mmcblk

[    2.564084] b318             128 mmcblk0rpmb  (driver?)

[    2.569370] b310            1024 mmcblk0boot1  (driver?)

[    2.574795] b308            1024 mmcblk0boot0  (driver?)

[    2.580274] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(179,2)

[markusniebel]

Hello Javier,

depending on the eMMC used and the kernel version this can also be a problem in the MMC driver stack. I remember we saw also these kind of errors in some situations on our i.MX base modules.

Background: there is a lot of fixing in handling timout and recover from failed commands in the mainline kernels. If you currently use an SDK kernel, could you try current mainline?

Regards

Markus

[igorpadykov]

Hi Javier

in general such errors may be caused by signal

integrity (poor signal shape), it may be recommended to

tweak driver strength of i.MX6 pads with IOMUXC_SW_PAD_CTL_PAD

SPEED,DSE,SRE settings and recheck board layout

sect.3.5.8 High speed signal routing recommendations IMX6DQ6SDLHDG

for SD module interfaces. One can try to work with decreased operating frequency.

Best regards

igor

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