kernel/drivers/net/ipa/ipa_clock.c, branch linux-6.9.y

net: ipa: rename "ipa_clock.c"

2021-08-22T08:44:17Z

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

2021-08-22T08:44:17Z

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

2021-08-22T08:44:17Z

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()

2021-08-20T13:45:47Z

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: fix TX queue race

2021-08-20T13:43:39Z

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

net: ipa: distinguish system from runtime suspend

2021-08-14T13:13:38Z

Add a new flag that is set when the hardware is suspended due to a system suspend operation, distingishing it from runtime suspend. Use it in the SUSPEND IPA interrupt handler to determine whether to trigger a system resume because of the event. Define new suspend and resume power management callback functions to set and clear the new flag, respectively. Signed-off-by: Alex Elder Signed-off-by: David S. Miller

net: ipa: enable wakeup in ipa_power_setup()

2021-08-14T13:13:38Z

Move the call to enable the IPA interrupt as a wakeup interrupt into ipa_power_setup(), disable it in ipa_power_teardown(). Signed-off-by: Alex Elder Signed-off-by: David S. Miller

net: ipa: kill ipa_clock_get_additional()

2021-08-11T12:31:56Z

Now that ipa_clock_get_additional() is a trivial wrapper around pm_runtime_get_if_active(), just open-code it in its only caller and delete the function. Signed-off-by: Alex Elder Signed-off-by: David S. Miller

net: ipa: kill IPA clock reference count

2021-08-11T12:31:56Z

The runtime power management core code maintains a usage count. This count mirrors the IPA clock reference count, and there's no need to maintain both. So get rid of the IPA clock reference count and just rely on the runtime PM usage count to determine when the hardware should be suspended or resumed. Use pm_runtime_get_if_active() in ipa_clock_get_additional(). We care whether power is active, regardless of whether it's in use, so pass true for its ign_usage_count argument. The IPA clock mutex is just used to make enabling/disabling the clock and updating the reference count occur atomically. Without the reference count, there's no need for the mutex, so get rid of that too. Signed-off-by: Alex Elder Signed-off-by: David S. Miller

net: ipa: use runtime PM core

2021-08-11T12:31:56Z

Use the runtime power management core to cause hardware suspend and resume to occur. Enable it in ipa_clock_init() (without autosuspend), and disable it in ipa_clock_exit(). Use ipa_runtime_suspend() as the ->runtime_suspend power operation, and arrange for it to be called by having ipa_clock_get() call pm_runtime_get_sync() when the first clock reference is taken. Similarly, use ipa_runtime_resume() as the ->runtime_resume power operation, and pm_runtime_put() when the last IPA clock reference is dropped. Introduce ipa_runtime_idle() as the ->runtime_idle power operation, and have it return a non-zero value; this way suspend will never occur except when forced. Use pm_runtime_force_suspend() and pm_runtime_force_resume() as the system suspend and resume callbacks, and remove ipa_suspend() and ipa_resume(). Store a pointer to the device structure passed to ipa_clock_init(), so it can be used by ipa_clock_exit() to disable runtime power management. For now we preserve IPA clock reference counting. Signed-off-by: Alex Elder Signed-off-by: David S. Miller