We are using an imx6 based board and are trying to write to the emmc using the UMS mode in u-boot. However we are noticing that the UMS connection drops after about 10 seconds or so. We checked the dmesg log from the host machine but do not see errors. This issue happens on our boards with swissbit eMMC SFEM016GB1ED1TO-I-5E-111-STD or SFEM016GB2ED1TO-I-5E-111-STD.
On our boards with Toshiba eMMC THGBMHG7C2LBAU8 or THGBMHG7C2LBAU7, the UMS mode works fine without any problems.
Below is the log from our Ubuntu host machine:
[20133.827201] usb 1-1: New USB device found, idVendor=0525, idProduct=a4a5, bcdDevice= 2.21
[20133.827203] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[20133.827204] usb 1-1: Product: USB download gadget
[20133.827205] usb 1-1: Manufacturer: FSL
[20133.832557] usb-storage 1-1:1.0: USB Mass Storage device detected
[20133.833039] usb-storage 1-1:1.0: Quirks match for vid 0525 pid a4a5: 10000
[20133.833263] scsi host33: usb-storage 1-1:1.0
[20134.850671] scsi 33:0:0:0: Direct-Access Linux UMS disk 0 ffff PQ: 0 ANSI: 2
[20134.851363] sd 33:0:0:0: Attached scsi generic sg2 type 0
[20134.855672] sd 33:0:0:0: [sdb] 3072000 512-byte logical blocks: (1.57 GB/1.46 GiB)
[20134.858148] sd 33:0:0:0: [sdb] Write Protect is off
[20134.858150] sd 33:0:0:0: [sdb] Mode Sense: 0f 00 00 00
[20134.860631] sd 33:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[20134.942789] sd 33:0:0:0: [sdb] Attached SCSI removable disk
[20135.827214] EXT4-fs (sdb): recovery complete
[20135.835505] EXT4-fs (sdb): mounted filesystem with ordered data mode. Opts: (null)
<disconnect happens some 10 seconds or so later>
[20146.594430] usb 1-1: USB disconnect, device number 6
U-boot version: U-Boot 2016.11 (May 16 2018 - 12:31:39 -0700)
Output of the "mmc info" u-boot command:
=> mmc info
Device: FSL_SDHC
Manufacturer ID: fb
OEM: 11c
Name: 00032
Tran Speed: 52000000
Rd Block Len: 512
MMC version 5.1
High Capacity: Yes
Capacity: 28.8 GiB
Bus Width: 8-bit
Erase Group Size: 512 KiB
HC WP Group Size: 8 MiB
User Capacity: 28.8 GiB WRREL
Boot Capacity: 31.5 MiB ENH
RPMB Capacity: 4 MiB ENH
If someone has any suggestions or tips that can help debug this issue, that would be helpful.
