From: DaveKucharczyk <david.kucharczyk@gmail.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] MMC write failed - Can't read partition table
Date: Tue, 8 Nov 2016 12:31:24 -0700 (MST) [thread overview]
Message-ID: <1478633484791-272634.post@n7.nabble.com> (raw)
Hi, we've been using a new SD card for 6+ months without issues, but recently
noticed issues with newer releases. I'm not sure if it's the SD cards, our
burner stations or our build process. Were using U-Boot 2014.07
The problem is that we can't read/write to the SD card during boot. This
happens intermittently on freshly burned cards. 75% of the time it works.
Our bootcmd starts with ext2load mmc ... but obviously it fails due to
"can't read partition table".
Manually debugging in U-Boot if I run mmc rescan then it can read the
partition table, but if I reboot the system then the issue comes back upon
next power-up.
If I run rescan AND then saveenv then everything works after that.
My questions are:
1. Is it good practice to run mmc rescan as one of the first things in
bootcmd?
2. I'm a little confised as to why saveenv would cause the SD card to work
again *persistently*.
3. Any recommendations on getting root cause as to what it could be (SD
card, our burner stations or our build process)?
Troubleshooting steps below...
MX51 U-Boot > mmc info
Device: FSL_SDHC
Manufacturer ID: 87
OEM: 494f
Name: 004GB
Tran Speed: 50000000
Rd Block Len: 512
SD version 3.0
High Capacity: Yes
Capacity: 3.8 GiB
Bus Width: 1-bit
MX51 U-Boot > mmc part
Partition Map for MMC device 0 -- Partition Type: DOS
Part Start Sector Num Sectors UUID Type
** Can't read partition table on 0:0 **
MX51 U-Boot > mmc rescan
MX51 U-Boot > mmc part
Partition Map for MMC device 0 -- Partition Type: DOS
Part Start Sector Num Sectors UUID Type
1 31000 3844000 00000000-01 83
2 3882750 4037750 00000000-02 83
MX51 U-Boot > saveenv
Saving Environment to MMC...
reboot and everything works.
--
View this message in context: http://u-boot.10912.n7.nabble.com/MMC-write-failed-Can-t-read-partition-table-tp272634.html
Sent from the U-Boot mailing list archive at Nabble.com.
reply other threads:[~2016-11-08 19:31 UTC|newest]
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