[v3,0/7] Updates to MHI channel handling

Message

Bhaumik Bhatt Dec. 2, 2020, 11:40 p.m. UTC

MHI specification shows a state machine with support for STOP channel command
and the validity of certain state transitions. MHI host currently does not
provide any mechanism to stop a channel and restart it without resetting it.
There are also times when the device moves on to a different execution
environment while client drivers on the host are unaware of it and still
attempt to reset the channels facing unnecessary timeouts.

This series addresses the above areas to provide support for stopping an MHI
channel, resuming it back, improved documentation and improving upon channel
state machine handling in general.

This set of patches was tested on arm64 architecture.

v3:
-Updated documentation for channel transfer APIs to highlight differences
-Create separate patch for "allowing channel to be disabled from stopped state"

v2:
-Renamed the newly introduced APIs to mhi_start_transfer() / mhi_stop_transfer()
-Added improved documentation to avoid confusion with the new APIs
-Removed the __ prefix from mhi_unprepare_channel() API for consistency.

Bhaumik Bhatt (7):
  bus: mhi: core: Allow receiving a STOP channel command response
  bus: mhi: core: Allow channel to be disabled from stopped state
  bus: mhi: core: Improvements to the channel handling state machine
  bus: mhi: core: Add support to stop or start channel data transfers
  bus: mhi: core: Check execution environment for channel before issuing
    reset
  bus: mhi: core: Remove __ prefix for MHI channel unprepare function
  bus: mhi: Improve documentation on channel transfer setup APIs

 drivers/bus/mhi/core/init.c     |   9 +-
 drivers/bus/mhi/core/internal.h |  12 +++
 drivers/bus/mhi/core/main.c     | 229 +++++++++++++++++++++++++++-------------
 include/linux/mhi.h             |  45 +++++++-
 4 files changed, 220 insertions(+), 75 deletions(-)