kernel/drivers/net/ipa/ipa_clock.h, 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: 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: 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: have ipa_clock_get() return a value

2021-08-11T12:31:55Z

We currently assume no errors occur when enabling or disabling the IPA core clock and interconnects. And although this commit exposes errors that could occur, we generally assume this won't happen in practice. This commit changes ipa_clock_get() and ipa_clock_put() so each returns a value. The values returned are meant to mimic what the runtime power management functions return, so we can set up error handling here before we make the switch. Have ipa_clock_get() increment the reference count even if it returns an error, to match the behavior of pm_runtime_get(). More details follow. When taking a reference in ipa_clock_get(), return 0 for the first reference, 1 for subsequent references, or a negative error code if an error occurs. Note that if ipa_clock_get() returns an error, we must not touch hardware; in some cases such errors now cause entire blocks of code to be skipped. When dropping a reference in ipa_clock_put(), we return 0 or an error code. The error would come from ipa_clock_disable(), which now returns what ipa_interconnect_disable() returns (either 0 or a negative error code). For now, callers ignore the return value; if an error occurs, a message will have already been logged, and little more can actually be done to improve the situation. Signed-off-by: Alex Elder Signed-off-by: David S. Miller

net: ipa: move ipa_suspend_handler()

2021-08-05T10:27:05Z

Move ipa_suspend_handler() into "ipa_clock.c" from "ipa_main.c", to group with the reset of the suspend/resume code. This IPA interrupt is triggered if an IPA RX endpoint is suspended but has a packet to be delivered. Introduce ipa_power_setup() and ipa_power_teardown() to add and remove the handler for the IPA SUSPEND interrupt at the same place as before, while allowing the handler to remain private. The "power" naming convention will be adopted elsewhere in this file as well (soon). Signed-off-by: Alex Elder Signed-off-by: David S. Miller

net: ipa: move IPA power operations to ipa_clock.c

2021-08-05T10:27:05Z

Move ipa_suspend() and ipa_resume(), as well as the definition of the ipa_pm_ops structure into "ipa_clock.c". Make ipa_pm_ops public and declare it as extern in "ipa_clock.h". This is part of centralizing IPA power management functionality into "ipa_clock.c" (the file will eventually get a name change). Signed-off-by: Alex Elder Signed-off-by: David S. Miller

net: ipa: define clock and interconnect data

2020-11-21T02:44:59Z

Define a new type of configuration data, used to initialize the IPA core clock and interconnects. This is the first of three patches, and defines the data types and interface but doesn't yet use them. Switch the return value if there is no matching configuration data to ENODEV instead of ENOTSUPP (to avoid using the nonstandard errno). Signed-off-by: Alex Elder Signed-off-by: Jakub Kicinski