linux.git/drivers/net/ipa, branch v5.15-rc2

net: ipa: initialize all filter table slots

2021-09-08T11:10:33+00:00

There is an off-by-one problem in ipa_table_init_add(), when
initializing filter tables.

In that function, the number of filter table entries is determined
based on the number of set bits in the filter map.  However that
count does *not* include the extra "slot" in the filter table that
holds the filter map itself.  Meanwhile, ipa_table_addr() *does*
include the filter map in the memory it returns, but because the
count it's provided doesn't include it, it includes one too few
table entries.

Fix this by including the extra slot for the filter map in the count
computed in ipa_table_init_add().

Note: ipa_filter_reset_table() does not have this problem; it resets
filter table entries one by one, but does not overwrite the filter
bitmap.

Fixes: 2b9feef2b6c2 ("soc: qcom: ipa: filter and routing tables")
Signed-off-by: Alex Elder 
Signed-off-by: David S. Miller

net: ipa: rename "ipa_clock.c"

2021-08-22T08:44:17+00:00

Finally, rename "ipa_clock.c" to be "ipa_power.c" and "ipa_clock.h"
to be "ipa_power.h".

Signed-off-by: Alex Elder 
Signed-off-by: David S. Miller

net: ipa: rename ipa_clock_* symbols

2021-08-22T08:44:17+00:00

Rename a number of functions to clarify that there is no longer a
notion of an "IPA clock," but rather that the functions are more
generally related to IPA power management.

  ipa_clock_enable() -> ipa_power_enable()
  ipa_clock_disable() -> ipa_power_disable()
  ipa_clock_rate() -> ipa_core_clock_rate()
  ipa_clock_init() -> ipa_power_init()
  ipa_clock_exit() -> ipa_power_exit()

Rename the ipa_clock structure to be ipa_power.  Rename all
variables and fields using that structure type "power" rather
than "clock".

Rename the ipa_clock_data structure to be ipa_power_data, and more
broadly, just substitute "power" for "clock" in places that
previously represented things related to the "IPA clock".

Update comments throughout.

Signed-off-by: Alex Elder 
Signed-off-by: David S. Miller

net: ipa: use autosuspend

2021-08-22T08:44:17+00:00

Use runtime power management autosuspend.

Up until this point, we only suspended the IPA hardware for system
suspend; now we'll suspend it aggressively using runtime power
management, setting the initial autosuspend delay to half a second
of inactivity.

Replace pm_runtime_put() calls with pm_runtime_put_autosuspend(),
call pm_runtime_mark_last_busy() before each of those.  In places
where we're shutting things down, or decrementing power references
for errors, use pm_runtime_put_noidle() instead.

Finally, remove ipa_runtime_idle(), so the ->runtime_suspend
callback will occur if idle.

Signed-off-by: Alex Elder 
Signed-off-by: David S. Miller

net: ipa: kill ipa_clock_get()

2021-08-20T13:45:47+00:00

The only remaining user of the ipa_clock_{get,put}() interface is
ipa_isr_thread().  Replace calls to ipa_clock_get() there calling
pm_runtime_get_sync() instead.  And call pm_runtime_put() there
rather than ipa_clock_put().  Warn if we ever get an error.

With that, we can get rid of ipa_clock_get() and ipa_clock_put().

Signed-off-by: Alex Elder 
Signed-off-by: David S. Miller

net: ipa: don't use ipa_clock_get() in "ipa_modem.c"

2021-08-20T13:45:47+00:00

When we open or close the modem network device we need to ensure the
hardware is powered.  Replace the callers of ipa_clock_get() found
in ipa_open() and ipa_stop() with calls to pm_runtime_get_sync().
If an error is returned, simply return that error to the caller
(without any error or warning message).  This could conceivably
occur if the function was called while the system was suspended,
but that really shouldn't happen.  Replace corresponding calls to
ipa_clock_put() with pm_runtime_put() also.

If the modem crashes we also need to ensure the hardware is powered
to recover.  If getting power returns an error there's not much we
can do, but at least report the error.  (Ideally the remoteproc SSR
code would ensure the AP was not suspended when it sends the
notification, but that is not (yet) the case.)

Signed-off-by: Alex Elder 
Signed-off-by: David S. Miller

net: ipa: don't use ipa_clock_get() in "ipa_uc.c"

2021-08-20T13:45:47+00:00

Replace the ipa_clock_get() call in ipa_uc_clock() when taking the
"proxy" clock reference for the microcontroller with a call to
pm_runtime_get_sync().  Replace calls of ipa_clock_put() for the
microcontroller with pm_runtime_put() calls instead.

There is a chance we get an error when taking the microcontroller
power reference.  This is an unlikely scenario, where system suspend
is initiated just before we learn the modem is booting.  For now
we'll just accept that this could occur, and report it if it does.

Signed-off-by: Alex Elder 
Signed-off-by: David S. Miller

net: ipa: don't use ipa_clock_get() in "ipa_smp2p.c"

2021-08-20T13:45:47+00:00

If the "modem-init" Device Tree property is present for a platform,
the modem performs early IPA hardware initialization, and signals
this is complete with an "ipa-setup-ready" SMP2P interrupt.  This
triggers a call to ipa_setup(), which requires the hardware to be
powered.

Replace the call to ipa_clock_get() in this case with a call to
pm_runtime_get_sync().  And replace the corresponding calls to
ipa_clock_put() with calls to pm_runtime_put() instead.

There is a chance we get an error when taking this power reference.
This is an unlikely scenario, where system suspend is initiated just
before the modem signals it has finished initializing the IPA
hardware.  For now we'll just accept that this could occur, and
report it if it does.

Signed-off-by: Alex Elder 
Signed-off-by: David S. Miller

net: ipa: don't use ipa_clock_get() in "ipa_main.c"

2021-08-20T13:45:47+00:00

We need the hardware to be powered starting at the config stage of
initialization when the IPA driver probes.  And we need it powered
when the driver is removed, at least until the deconfig stage has
completed.

Replace callers of ipa_clock_get() in ipa_probe() and ipa_exit(),
calling pm_runtime_get_sync() instead.  Replace the corresponding
callers of ipa_clock_put(), calling pm_runtime_put() instead.

The only error we expect when getting power would occur when the
system is suspended.  The ->probe and ->remove driver callbacks
won't be called when suspended, so issue a WARN() call if an error
is seen getting power.

Signed-off-by: Alex Elder 
Signed-off-by: David S. Miller

net: ipa: fix TX queue race

2021-08-20T13:43:39+00:00

Jakub Kicinski pointed out a race condition in ipa_start_xmit() in a
recently-accepted series of patches:
  https://lore.kernel.org/netdev/20210812195035.2816276-1-elder@linaro.org/
We are stopping the modem TX queue in that function if the power
state is not active.  We restart the TX queue again once hardware
resume is complete.

  TX path                       Power Management
  -------                       ----------------
  pm_runtime_get(); no power    Start resume
  Stop TX queue                      ...
  pm_runtime_put()              Resume complete
  return NETDEV_TX_BUSY         Start TX queue

  pm_runtime_get()
  Power present, transmit
  pm_runtime_put()              (auto-suspend)

The issue is that the power management (resume) activity and the
network transmit activity can occur concurrently, and there's a
chance the queue will be stopped *after* it has been started again.

  TX path                       Power Management
  -------                       ----------------
                                Resume underway
  pm_runtime_get(); no power         ...
                                Resume complete
                                Start TX queue
  Stop TX queue       <-- No more transmits after this
  pm_runtime_put()
  return NETDEV_TX_BUSY

We address this using a STARTED flag to indicate when the TX queue
has been started from the resume path, and a spinlock to make the
flag and queue updates happen atomically.

  TX path                       Power Management
  -------                       ----------------
                                Resume underway
  pm_runtime_get(); no power    Resume complete
                                start TX queue     \
  If STARTED flag is *not* set:                     > atomic
      Stop TX queue             set STARTED flag   /
  pm_runtime_put()
  return NETDEV_TX_BUSY

A second flag is used to address a different race that involves
another path requesting power.

  TX path            Other path              Power Management
  -------            ----------              ----------------
                     pm_runtime_get_sync()   Resume
                                             Start TX queue   \ atomic
                                             Set STARTED flag /
                     (do its thing)
                     pm_runtime_put()
                                             (auto-suspend)
  pm_runtime_get()                           Mark delayed resume
  STARTED *is* set, so
    do *not* stop TX queue  <-- Queue should be stopped here
  pm_runtime_put()
  return NETDEV_TX_BUSY                      Suspend done, resume
                                             Resume complete
  pm_runtime_get()
  Stop TX queue
    (STARTED is *not* set)                   Start TX queue   \ atomic
  pm_runtime_put()                           Set STARTED flag /
  return NETDEV_TX_BUSY

So a STOPPED flag is set in the transmit path when it has stopped
the TX queue, and this pair of operations is also protected by the
spinlock.  The resume path only restarts the TX queue if the STOPPED
flag is set.  This case isn't a major problem, but it avoids the
"non-trivial amount of useless work" done by the networking stack
when NETDEV_TX_BUSY is returned.

Fixes: 6b51f802d652b ("net: ipa: ensure hardware has power in ipa_start_xmit()")
Signed-off-by: Alex Elder 
Signed-off-by: David S. Miller