2011/8/18 Felipe Balbi <balbi@xxxxxx>: > Hi, > > On Wed, Aug 17, 2011 at 10:52:59PM -0700, Barry Song wrote: >> From: Peiyu Li <peiyu.li@xxxxxxx> >> >> Now the mass storage driver has fixed logic block size of 512 bytes. >> >> The mass storage gadget read/write bound devices only through VFS, so the bottom level >> devices actually are just RAW devices to the driver and connected PC. As a RAW, hosts >> can always format, read and write it right in 512 bytes logic block and don't care about >> the actual logic block size of devices bound to the gadget. >> >> But if we want to share the bound block device partition between target board and PC, >> in case the logic block size of the bound block device is 4KB, we execute the following >> steps: >> 1. connect a board with mass storage gadget to PC(the board has set one partition of >> on-board block device as file name of the mass storage) >> 2. PC format the mass storage to VFAT by default logic block size and read/write it >> 3. disconnect boards from PC >> 4. target board mount the partition as VFAT >> Step 4 will fail since kernel on target thinks the logic block size of the bound partition >> as 4KB. >> A typical error is >> "FAT: logical sector size too small for device (logical sector size = 512)" >> >> If we execute opposite steps: >> 1. format the partition to VFAT on target board and read/write this partition >> 2. connect the board to Windows PC as usb mass storage gadget, windows will think the disk >> is not formatted >> >> So the conclusion is that only as a gadget, the mass storage driver has no any problem. >> But being shared VFAT or other filesystem on PC and target board, it will fail. >> >> This patch adapts logic block size to bound block devices and fix the issue. >> >> Cc: Michal Nazarewicz <mina86@xxxxxxxxxx> >> Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> >> Signed-off-by: Peiyu Li <peiyu.li@xxxxxxx> >> Signed-off-by: Xianglong Du <xianglong.du@xxxxxxx> >> Signed-off-by: Huayi Li <huayi.li@xxxxxxx> >> Signed-off-by: Barry Song <Baohua.Song@xxxxxxx> > > Alan, can I have your Ack on this one if you're ok with the patch ? might also the Ack from Michal Nazarewicz, i think. > > -- > balbi > -barry -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
