On 02/01/08 04:48, Matthew Dharm wrote: > On Mon, Dec 31, 2007 at 04:55:21PM -0500, Alan Stern wrote: > >> On Mon, 31 Dec 2007, Bruce Schultz wrote: >> >>> I have a USB SD card reader which has never worked properly and finally got >>> me >>> annoyed enough to try to do something about it. Using a 2.6.22 kernel >>> (gentoo), I get the following output in dmesg when I plug it in (with a >>> 128MB >>> SD card inserted): >>> >>> sd 8:0:0:0: [sdb] 248320 512-byte hardware sectors (127 MB) >>> sd 8:0:0:0: [sdb] Write Protect is off >>> sd 8:0:0:0: [sdb] Mode Sense: 03 00 00 00 >>> sd 8:0:0:0: [sdb] Assuming drive cache: write through >>> sd 8:0:0:0: [sdb] 248320 512-byte hardware sectors (127 MB) >>> sd 8:0:0:0: [sdb] Write Protect is off >>> sd 8:0:0:0: [sdb] Mode Sense: 03 00 00 00 >>> sd 8:0:0:0: [sdb] Assuming drive cache: write through >>> sdb: sdb1 >>> end_request: I/O error, dev sdb, sector 248313 >>> >> ... >> >>> After a bit of googling, I tried patching unusual_devs.h, which got me far >>> enough to be able to mount /dev/sdb1 and I seem to be able to read/write to >>> the SD card, but with errors in the dmesg output still. So I guess I'm on >>> the >>> right track, but maybe there's something else I'm missing? Any pointers out >>> there? >>> >> You need to do a low-level format of the card. Delete and then >> recreate the first partition. And then of course you'll have to >> recreate the VFAT filesystem on it. >> > That will work, but I don't think it's optimal. > Indeed, this does definitely work, but I agree that is not optimal to reformat every new SD card which gets used in it. At least it is mostly usable for its most typical purpose, namely copying photos off of friends' cameras, although I have found a card which refused to copy 1 file completely, I guess because part of the file was in the last sector. > Looking at the logs provided, I think this might be one of those devices > that doesn't like reading the last sector if it's part of a multi-sector > request. > I'll have a closer look into the recent patch I saw on the list for HP printer card readers, and report back if I have any success with that.
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