[PATCH net-next v2 0/7] net: ipa: wake up system on RX available

Alex Elder
2020-09-12T00:48:58Z

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.
Version 2 replaces the first patch from version 1 with three
patches, in response to David Miller's feedback.

Specifically:
- The first patch now replaces an atomic_t field with a
refcount_t. The affected field is not the one David
commented on, but this fix is consistent with what he
asked for.
- The second patch replaces the atomic_t field David *did*
comment on with a single bit in a new bitmap field;
ultimately what's needed there is a Boolean flag anyway.
- The third patch is renamed, but basically does the same
thing the first patch did in version 1. It now operates
on a bit in a bitmap rather than on an atomic variable.

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,
takes 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 three patches in the series were described above. 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 (7):
net: ipa: use refcount_t for IPA clock reference count
net: ipa: replace ipa->suspend_ref with a flag bit
net: ipa: verify reference flag values
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 | 16 +++++--
drivers/net/ipa/ipa_clock.c | 28 +++++-------
drivers/net/ipa/ipa_interrupt.c | 14 ++++++
drivers/net/ipa/ipa_main.c | 76 +++++++++++++++++++--------------
6 files changed, 84 insertions(+), 68 deletions(-)

--
2.20.1