[OEM-5.14] [PATCH 1/3] bus: mhi: core: Add support for forced PM resume

[Kai-Heng Feng]

From: Loic Poulain <loic.poulain at linaro.org>

BugLink: https://bugs.launchpad.net/bugs/1955613

For whatever reason, some devices like QCA6390, WCN6855 using ath11k
are not in M3 state during PM resume, but still functional. The
mhi_pm_resume should then not fail in those cases, and let the higher
level device specific stack continue resuming process.

Add an API mhi_pm_resume_force(), to force resuming irrespective of the
current MHI state. This fixes a regression with non functional ath11k WiFi
after suspend/resume cycle on some machines.

Bug report: https://bugzilla.kernel.org/show_bug.cgi?id=214179

Link: https://lore.kernel.org/regressions/871r5p0x2u.fsf@codeaurora.org/
Fixes: 020d3b26c07a ("bus: mhi: Early MHI resume failure in non M3 state")
Cc: stable at vger.kernel.org #5.13
Reported-by: Kalle Valo <kvalo at codeaurora.org>
Reported-by: Pengyu Ma <mapengyu at gmail.com>
Tested-by: Kalle Valo <kvalo at kernel.org>
Acked-by: Kalle Valo <kvalo at kernel.org>
Signed-off-by: Loic Poulain <loic.poulain at linaro.org>
[mani: Switched to API, added bug report, reported-by tags and CCed stable]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam at linaro.org>
Link: https://lore.kernel.org/r/20211209131633.4168-1-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(cherry picked from commit cab2d3fd6866e089b5c50db09dece131f85bfebd)
Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
---
 drivers/bus/mhi/core/pm.c             | 21 ++++++++++++++++++---
 drivers/net/wireless/ath/ath11k/mhi.c |  6 +++++-
 include/linux/mhi.h                   | 13 +++++++++++++
 3 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
index bbf6cd04861eb..3f588f33ed429 100644
--- a/drivers/bus/mhi/core/pm.c
+++ b/drivers/bus/mhi/core/pm.c
@@ -881,7 +881,7 @@ int mhi_pm_suspend(struct mhi_controller *mhi_cntrl)
 }
 EXPORT_SYMBOL_GPL(mhi_pm_suspend);
 
-int mhi_pm_resume(struct mhi_controller *mhi_cntrl)
+static int __mhi_pm_resume(struct mhi_controller *mhi_cntrl, bool force)
 {
 	struct mhi_chan *itr, *tmp;
 	struct device *dev = &mhi_cntrl->mhi_dev->dev;
@@ -898,8 +898,12 @@ int mhi_pm_resume(struct mhi_controller *mhi_cntrl)
 	if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state))
 		return -EIO;
 
-	if (mhi_get_mhi_state(mhi_cntrl) != MHI_STATE_M3)
-		return -EINVAL;
+	if (mhi_get_mhi_state(mhi_cntrl) != MHI_STATE_M3) {
+		dev_warn(dev, "Resuming from non M3 state (%s)\n",
+			 TO_MHI_STATE_STR(mhi_get_mhi_state(mhi_cntrl)));
+		if (!force)
+			return -EINVAL;
+	}
 
 	/* Notify clients about exiting LPM */
 	list_for_each_entry_safe(itr, tmp, &mhi_cntrl->lpm_chans, node) {
@@ -940,8 +944,19 @@ int mhi_pm_resume(struct mhi_controller *mhi_cntrl)
 
 	return 0;
 }
+
+int mhi_pm_resume(struct mhi_controller *mhi_cntrl)
+{
+	return __mhi_pm_resume(mhi_cntrl, false);
+}
 EXPORT_SYMBOL_GPL(mhi_pm_resume);
 
+int mhi_pm_resume_force(struct mhi_controller *mhi_cntrl)
+{
+	return __mhi_pm_resume(mhi_cntrl, true);
+}
+EXPORT_SYMBOL_GPL(mhi_pm_resume_force);
+
 int __mhi_device_get_sync(struct mhi_controller *mhi_cntrl)
 {
 	int ret;
diff --git a/drivers/net/wireless/ath/ath11k/mhi.c b/drivers/net/wireless/ath/ath11k/mhi.c
index 75cc2d80fde8d..c6f8a3e7725e7 100644
--- a/drivers/net/wireless/ath/ath11k/mhi.c
+++ b/drivers/net/wireless/ath/ath11k/mhi.c
@@ -532,7 +532,11 @@ static int ath11k_mhi_set_state(struct ath11k_pci *ab_pci,
 		ret = mhi_pm_suspend(ab_pci->mhi_ctrl);
 		break;
 	case ATH11K_MHI_RESUME:
-		ret = mhi_pm_resume(ab_pci->mhi_ctrl);
+		/* Do force MHI resume as some devices like QCA6390, WCN6855
+		 * are not in M3 state but they are functional. So just ignore
+		 * the MHI state while resuming.
+		 */
+		ret = mhi_pm_resume_force(ab_pci->mhi_ctrl);
 		break;
 	case ATH11K_MHI_TRIGGER_RDDM:
 		ret = mhi_force_rddm_mode(ab_pci->mhi_ctrl);
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index 944aa3aa30355..f56f7320af535 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -659,6 +659,19 @@ int mhi_pm_suspend(struct mhi_controller *mhi_cntrl);
  */
 int mhi_pm_resume(struct mhi_controller *mhi_cntrl);
 
+/**
+ * mhi_pm_resume_force - Force resume MHI from suspended state
+ * @mhi_cntrl: MHI controller
+ *
+ * Resume the device irrespective of its MHI state. As per the MHI spec, devices
+ * has to be in M3 state during resume. But some devices seem to be in a
+ * different MHI state other than M3 but they continue working fine if allowed.
+ * This API is intented to be used for such devices.
+ *
+ * Return: 0 if the resume succeeds, a negative error code otherwise
+ */
+int mhi_pm_resume_force(struct mhi_controller *mhi_cntrl);
+
 /**
  * mhi_download_rddm_image - Download ramdump image from device for
  *                           debugging purpose.
-- 
2.33.1