linux-kernel - [PATCH net-next 0/5] net: ipa: wake up system on RX available

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Date:   Tue,  8 Sep 2020 19:21:22 -0500
From:   Alex Elder <elder@...aro.org>
To:     davem@...emloft.net, kuba@...nel.org
Cc:     evgreen@...omium.org, subashab@...eaurora.org,
        cpratapa@...eaurora.org, bjorn.andersson@...aro.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH net-next 0/5] net: ipa: wake up system on RX available

This series arranges for the IPA driver to wake up a suspended
system if the IPA hardware has a packet to deliver to the AP.

Currently, the GSI interrupt is set up to be a waking interrupt.
But the GSI interrupt won't actually fire for a stopped channel (or
a channel that underlies a suspended endpoint).  The fix involves
having the IPA rather than GSI interrupt wake up the AP.

The IPA hardware clock is managed by both the modem and the AP.
Even if the AP is in a fully-suspended state, the modem can clock
the IPA hardware, and can send a packet through IPA that is destined
for an endpoint on the AP.

When the IPA hardware finds a packet's destination is stopped or
suspended, it sends an *IPA interrupt* to the destination "execution
environment" (EE--in this case, the AP).  The desired behavior is
for the EE (even if suspended) to be able to handle the incoming
packet.

To do this, we arrange for the IPA interrupt to be a wakeup
interrupt.  And if the system is suspended when that interrupt
fires, we trigger a system resume operation.  While resuming the
system, the IPA driver starts all its channels (or for SDM845, take
its endpoints out of suspend mode).

Whenever an RX channel is started, if it has a packet ready to be
consumed, the GSI interrupt will fire.  At this point the inbound
packet that caused this wakeup activity will be received.

The first patch just checks the previous value of a reference
counter used for suspend, as precaution to catch bugs.  The next
three arrange for the IPA interrupt wake up the system.  Finally,
with this design, we no longer want the GSI interrupt to wake a
suspended system, so that is removed by the last patch.`

					-Alex

Alex Elder (5):
  net: ipa: use atomic exchange for suspend reference
  net: ipa: manage endpoints separate from clock
  net: ipa: use device_init_wakeup()
  net: ipa: enable wakeup on IPA interrupt
  net: ipa: do not enable GSI interrupt for wakeup

 drivers/net/ipa/gsi.c           | 17 +++------
 drivers/net/ipa/gsi.h           |  1 -
 drivers/net/ipa/ipa.h           |  2 --
 drivers/net/ipa/ipa_clock.c     |  4 ---
 drivers/net/ipa/ipa_interrupt.c | 14 ++++++++
 drivers/net/ipa/ipa_main.c      | 62 ++++++++++++++++++---------------
 6 files changed, 51 insertions(+), 49 deletions(-)

-- 
2.20.1