fix false disconnect due to a signal sent to the reading process

- In the current implementation, when a signal is sent to the reading process,
  read is cancelled by calling usb_ep_dequeue, which lead into calling
  acc_complete_out with ECONNRESET, but the current logic treats it as
  disconnection, which makes the device inaccessible until cable is actually
  disconnected.
- The fix calls disconnect only when ESHUTDOWN error is passed.
- If data has already arrived while trying cancelling, the data is marked
  as available, and it will be read out on the next read. This is necessary
  as USB bulk is assumed to guarantee no data loss.

Signed-off-by: keunyoung <keunyoung@google.com>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
msm: kgsl: Don't block on detach if the context is invalid

An invalidated context means that something pretty nasty happened and
likely there was an unrecovered GPU fault along the way. If this is
the case then the GPU is likely not processing commands for the context
anymore. Don't block for the last retired global if the context was
invalidated.

Change-Id: Ic0dedbad22a22b704baf14557d7e18cc4cf1044a
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
msm: kgsl: Refcount mmu clock calls and allow multiple disable events

Allow each mmu clock enable call to enable the clock and let the
clock driver refcounting mechanism deal with switching the clock
off at the right time. This also means that each enable call should
have a disable call or a disable event registered, so allow for
multiple disable events to be registered. This simplifies the mmu
clock handling mechanism which is better for multiple ringbuffer
implementation. With multiple ringbuffers each global timestamp is
tied to a specific ringbuffer and with a single clock disable event
it is hard to figure out when the clock should be turned off.

CRs-fixed: 597193 592485
Change-Id: I924c545140bd19d95890a5fdfd0382c511abe973
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>
Signed-off-by: Tarun Karra <tkarra@codeaurora.org>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>