USB: fix inefficient copy of unaligned buffers

These patches (for 4.1) make sure that only the received data is copied from the temporary buffers used for unaligned transfers.

I discovered this when debugging an issue where the Beaglebone Black would lock up on disconnect.

Turns out it was related to the transfer_buffers not being properly aligned, causing musb to use temporary buffers for the transfers. On transfer errors (e.g. during disconnect), the full buffer content was still being copied, something which would alter timings enough to prevent the disconnect from being detected and processed.

The first patch in the series works around the problem in that particular set up, but obviously does not solve the underlying issue, which needs to be analysed further.

I also included a corresponding patch for ehci-tegra that has been compile tested only.

Note that the octeon-hcd driver in staging, which also uses temporary buffers for unaligned transfers, was broken for isochronous transfers. The third patch fixes that, but is also untested due to lack of hardware.

Johan

v2:
- Make sure to copy the full buffer for isochronous transfers, in which case the received data is not necessarily contiguous (thanks Alan).
- Drop stable tags as this is really just an optimisation.

Johan Hovold (3):
USB: musb: fix inefficient copy of unaligned buffers
USB: ehci-tegra: fix inefficient copy of unaligned buffers
staging: octeon-usb: fix unaligned isochronous transfers

 drivers/staging/octeon-usb/octeon-hcd.c | 12 +++++++++---
 drivers/usb/host/ehci-tegra.c           | 12 +++++++++---
 drivers/usb/musb/musb_host.c            |  9 +++++++--
 3 files changed, 25 insertions(+), 8 deletions(-)

2.0.5