bus: mhi: core: Add support for forced PM resume

commit cab2d3fd6866e089b5c50db09dece131f85bfebd upstream.

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@vger.kernel.org #5.13
Reported-by: Kalle Valo <kvalo@codeaurora.org>
Reported-by: Pengyu Ma <mapengyu@gmail.com>
Tested-by: Kalle Valo <kvalo@kernel.org>
Acked-by: Kalle Valo <kvalo@kernel.org>
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
[mani: Switched to API, added bug report, reported-by tags and CCed stable]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20211209131633.4168-1-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
index fb99e37..547e6e7 100644 (file)
--- 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 26c7ae2..49c0b1a 100644 (file)
--- a/drivers/net/wireless/ath/ath11k/mhi.c
+++ b/drivers/net/wireless/ath/ath11k/mhi.c
@@ -533,7 +533,11 @@ 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 7239858..a5cc4cd 100644 (file)
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -664,6 +664,19 @@ 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.
  * @mhi_cntrl: MHI controller