Currently in ath11k we keep the firmware running on the WLAN device when the network interface (wlan0) is down. The problem is that this will break hibernation, obviously the firmware can't be running after the whole system is powered off. To power down the ath11k firmware for suspend/hibernation some changes both in MHI subsystem and ath11k are needed. This patchset fixes a longstanding bug report about broken hibernation support: https://bugzilla.kernel.org/show_bug.cgi?id=214649 There already is an RFC version which has been tested by multiple users with positive results: https://patchwork.kernel.org/project/linux-wireless/cover/20231127162022.518834-1-kvalo@xxxxxxxxxx/ Basically the RFC version adds two APIs to MHI stack: with the first one ath11k is able to keep MHI devices when going to suspend/hibernation, getting us rid of the probe deferral issue when resume back. while with the second one ath11k could manually prepare/unprepare MHI channels by itself, which is needed because QRTR doesn't probe those channels automatically in this case. Mani, the MHI maintainer, firstly doesn't like that version and insists that an MHI device should be destroyed when suspend/hibernation, according to his understanding on device driver model. See https://lore.kernel.org/mhi/20231127162022.518834-1-kvalo@xxxxxxxxxx/ After a long discussion Mani thought we might need a new PM callback with which ath11k is able to wait until kernel unblocks device probe and thus MHI channels get probed. So we came to the kernel PM list and there Mani realized that his understanding is not correct so he finally agrees to keep MHI device during suspend/hibernation. See https://lore.kernel.org/all/21cd2098-97e1-4947-a5bb-a97582902ead@xxxxxxxxxxx/ Mani also pointed out that an MHI controller driver (ath11k here) should not touch MHI channels directly because those channels are managed by the corresponding MHI client driver (QRTR here). To address this, we come up with this version. Compared with that RFC version, this version adds PM callbacks in QRTR module: suspend callback unprepares MHI channels during suspend and resume callback prepares those channels during resume. In this way ath11k doesn't need to do unprepare/prepare work by itself so those two APIs added in RFC version are removed now. The power down/up procedure requires a specific sequence in which PM callbacks of wiphy, ath11k and QRTR are called, this is achieved by exploiting the child-father relationship between their device struct, and also the PM framework which separates whole suspend/resume process into several stages. Details in patch [3/3]. v4: - resend v3 as v4 to CC netdev folks. No changes in patches themselves. v3: - skip QRTR suspend/resume if MHI device is found to be in suspend state. v2: - add comment on why destroying the device is optional in mhi_pm_disable_transition(). - rename mhi_power_down_no_destroy() as mhi_power_down_keep_dev(). - refine API description of mhi_power_down() and mhi_power_down_keep_dev(). - add/remove __maybe_unused to QRTR PM callbacks. - remove '#ifdef CONFIG_PM'. - refine commit log of patch 1/3 and 2/3. Baochen Qiang (3): bus: mhi: host: add mhi_power_down_keep_dev() net: qrtr: support suspend/hibernation wifi: ath11k: support hibernation drivers/bus/mhi/host/internal.h | 4 +- drivers/bus/mhi/host/pm.c | 42 ++++++++-- drivers/net/wireless/ath/ath11k/ahb.c | 6 +- drivers/net/wireless/ath/ath11k/core.c | 105 +++++++++++++++++-------- drivers/net/wireless/ath/ath11k/core.h | 6 +- drivers/net/wireless/ath/ath11k/hif.h | 14 +++- drivers/net/wireless/ath/ath11k/mhi.c | 12 ++- drivers/net/wireless/ath/ath11k/mhi.h | 5 +- drivers/net/wireless/ath/ath11k/pci.c | 44 +++++++++-- drivers/net/wireless/ath/ath11k/qmi.c | 2 +- include/linux/mhi.h | 18 ++++- net/qrtr/mhi.c | 46 +++++++++++ 12 files changed, 244 insertions(+), 60 deletions(-) base-commit: c39a5cfa0448f3afbee78373f16d87815a674f11 -- 2.25.1
