[PATCH 2/4] wifi: ath12k: do not wait in resume for a reset that cannot finish there

[Vladyslav Tymoshchuk <tvlad744@gmail.com>]

ath12k_core_resume() waits up to 20 s for restart_completed. When the
firmware crashes during the cold boot started by
ath12k_core_resume_early(), ath12k_core_reset() powers MHI down, which
destroys the MHI channel devices, and up again. The driver core does
not probe the new devices before the system resume is over
(device_block_probing()), so QMI cannot come up and the restart cannot
complete while ath12k_core_resume() is waiting for it:

  mhi mhi0: Wait for device to enter SBL or Mission mode
  ath12k_wifi7_pci 0000:01:00.0: timeout while waiting for restart complete
  ath12k_wifi7_pci 0000:01:00.0: failed to resume core: -110
  ath12k_wifi7_pci 0000:01:00.0: PM: dpm_run_callback(): pci_pm_resume returns -110
  PM: suspend exit
  ath12k_wifi7_pci 0000:01:00.0: fw_version 0x10097fff ...

The resume takes 20 s longer and fails.

Let ath12k_core_resume() go on as soon as a reset starts during the
resume. The restart then completes after the resume, as it does for a
crash at any other time.

Fixes: 8d5f4da8d70b ("wifi: ath12k: support suspend/resume")
Signed-off-by: Vladyslav Tymoshchuk <tvlad744@gmail.com>
---
 drivers/net/wireless/ath/ath12k/core.c | 6 ++++++
 drivers/net/wireless/ath/ath12k/core.h | 1 +
 2 files changed, 7 insertions(+)

diff --git a/drivers/net/wireless/ath/ath12k/core.c b/drivers/net/wireless/ath/ath12k/core.c
index 42a9cd28c652..b1d1247a0dc6 100644
--- a/drivers/net/wireless/ath/ath12k/core.c
+++ b/drivers/net/wireless/ath/ath12k/core.c
@@ -224,6 +224,7 @@ int ath12k_core_resume_early(struct ath12k_base *ab)
 		return ret;
 
 	reinit_completion(&ab->restart_completed);
+	WRITE_ONCE(ab->resuming, true);
 	ret = ath12k_hif_power_up(ab);
 	if (ret)
 		ath12k_warn(ab, "failed to power up hif during resume: %d\n", ret);
@@ -243,6 +244,7 @@ int ath12k_core_resume(struct ath12k_base *ab)
 
 	time_left = wait_for_completion_timeout(&ab->restart_completed,
 						ATH12K_RESET_TIMEOUT_HZ);
+	WRITE_ONCE(ab->resuming, false);
 	if (time_left == 0) {
 		ath12k_warn(ab, "timeout while waiting for restart complete");
 		return -ETIMEDOUT;
@@ -1727,6 +1729,10 @@ static void ath12k_core_reset(struct work_struct *work)
 	int reset_count, fail_cont_count, i;
 	long time_left;
 
+	/* The new MHI devices are probed only after the system resume */
+	if (READ_ONCE(ab->resuming))
+		complete(&ab->restart_completed);
+
 	if (!(test_bit(ATH12K_FLAG_QMI_FW_READY_COMPLETE, &ab->dev_flags))) {
 		ath12k_warn(ab, "ignore reset dev flags 0x%lx\n", ab->dev_flags);
 		return;
diff --git a/drivers/net/wireless/ath/ath12k/core.h b/drivers/net/wireless/ath/ath12k/core.h
index 3a92a4b03359..2d8d91afb66f 100644
--- a/drivers/net/wireless/ath/ath12k/core.h
+++ b/drivers/net/wireless/ath/ath12k/core.h
@@ -1072,6 +1072,7 @@ struct ath12k_base {
 	atomic_t reset_count;
 	atomic_t recovery_count;
 	bool is_reset;
+	bool resuming;
 	struct completion reset_complete;
 	/* continuous recovery fail count */
 	atomic_t fail_cont_count;
-- 
2.43.0