[U-Boot] usb_test_unit_ready called every block read - performance

Jim Shimer
2012-07-30T19:18:08Z

While tuning ext2load, we found that usb_test_unit_ready was being called
every block read. We compared the usb block storage to the scsi block
storage cmd_scsi.c, and found that the scsi device was only calling its
scsi_setup_test_unit_ready() during scsi_can. It appears that
usb_test_unit_ready() really only needs to be called once during
usb_stor_scan(), via usb_stor_get_info(). Is there a particular reason
usb_test_unit_ready is called for every block read, or do you think its ok
to only call during usb_stor_scan()? We're finding this speeds up ext2load
quite a bit.

Regards,
Jim

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*James H Shimer*
Motorola Mobility T3-12-HH72
900 Chelmsford Street
Lowell MA 08151
978-614-3550