| Message ID | 20240227063613.4478-1-quic_bqiang@quicinc.com |
|---|---|
| Headers | show |
| Series | wifi: ath11k: hibernation support | expand |
On Tue, Feb 27, 2024 at 02:36:12PM +0800, Baochen Qiang wrote: > MHI devices may not be destroyed during suspend/hibernation, so need > to unprepare/prepare MHI channels throughout the transition, this is > done by adding suspend/resume callbacks. > > The suspend callback is called in the late suspend stage, this means > MHI channels are still alive at suspend stage, and that makes it > possible for an MHI controller driver to communicate with others over > those channels at suspend stage. While the resume callback is called > in the early resume stage, for a similar reason. > > Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.30 > > Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> Could you please confirm if this patch can be applied separately and won't cause regression? - Mani > --- > net/qrtr/mhi.c | 27 +++++++++++++++++++++++++++ > 1 file changed, 27 insertions(+) > > diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c > index 9ced13c0627a..e96b82a6742c 100644 > --- a/net/qrtr/mhi.c > +++ b/net/qrtr/mhi.c > @@ -118,6 +118,32 @@ static const struct mhi_device_id qcom_mhi_qrtr_id_table[] = { > }; > MODULE_DEVICE_TABLE(mhi, qcom_mhi_qrtr_id_table); > > +static int __maybe_unused qcom_mhi_qrtr_pm_suspend_late(struct device *dev) > +{ > + struct mhi_device *mhi_dev = container_of(dev, struct mhi_device, dev); > + > + mhi_unprepare_from_transfer(mhi_dev); > + > + return 0; > +} > + > +static int __maybe_unused qcom_mhi_qrtr_pm_resume_early(struct device *dev) > +{ > + struct mhi_device *mhi_dev = container_of(dev, struct mhi_device, dev); > + int rc; > + > + rc = mhi_prepare_for_transfer_autoqueue(mhi_dev); > + if (rc) > + dev_err(dev, "failed to prepare for autoqueue transfer %d\n", rc); > + > + return rc; > +} > + > +static const struct dev_pm_ops qcom_mhi_qrtr_pm_ops = { > + SET_LATE_SYSTEM_SLEEP_PM_OPS(qcom_mhi_qrtr_pm_suspend_late, > + qcom_mhi_qrtr_pm_resume_early) > +}; > + > static struct mhi_driver qcom_mhi_qrtr_driver = { > .probe = qcom_mhi_qrtr_probe, > .remove = qcom_mhi_qrtr_remove, > @@ -126,6 +152,7 @@ static struct mhi_driver qcom_mhi_qrtr_driver = { > .id_table = qcom_mhi_qrtr_id_table, > .driver = { > .name = "qcom_mhi_qrtr", > + .pm = &qcom_mhi_qrtr_pm_ops, > }, > }; > > -- > 2.25.1 >
On 2/27/2024 5:56 PM, Manivannan Sadhasivam wrote: > On Tue, Feb 27, 2024 at 04:39:41PM +0800, Baochen Qiang wrote: >> >> >> On 2/27/2024 3:15 PM, Manivannan Sadhasivam wrote: >>> On Tue, Feb 27, 2024 at 02:36:12PM +0800, Baochen Qiang wrote: >>>> MHI devices may not be destroyed during suspend/hibernation, so need >>>> to unprepare/prepare MHI channels throughout the transition, this is >>>> done by adding suspend/resume callbacks. >>>> >>>> The suspend callback is called in the late suspend stage, this means >>>> MHI channels are still alive at suspend stage, and that makes it >>>> possible for an MHI controller driver to communicate with others over >>>> those channels at suspend stage. While the resume callback is called >>>> in the early resume stage, for a similar reason. >>>> >>>> Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.30 >>>> >>>> Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com> >>> >>> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> >>> >>> Could you please confirm if this patch can be applied separately and won't cause >>> regression? >> Just searched the kernel and found another two drivers using IPCR channels, >> one is pci_epf_mhi_driver in drivers/pci/endpoint/functions/pci-epf-mhi.c >> and the other is mhi_pci_driver in drivers/bus/mhi/host/pci_generic.c. >> >> For pci_epf_mhi_driver, this is not impacted because the devices for those >> channels are attached to mhi_ep_bus_type while QRTR MHI driver attached to >> mhi_bus_type. >> >> For mhi_pci_driver, I am afraid there would be regressions caused by this >> patch. The regression is because when system suspends, mhi_pci_suspend() is >> called and then qcom_mhi_qrtr_pm_suspend_late() called, however the latter >> would fail because MHI is moved to M3 state by call mhi_pm_suspend() in >> mhi_pci_suspend(). To address this, there might be two options: the first is >> to move mhi_pci_suspend() to a late suspend stage which would be called >> after qcom_mhi_qrtr_pm_suspend_late(). and the second is to avoid whole QRTR >> suspend operation in such cases. I prefer the second one, because if MHI is >> going to suspend, instead of power down, it is pointless to unprepare MHI >> channels and re-prepare them after resume back. We can achieve this purpose >> by adding a status_cb() to QRTR MHI driver which would be called when MHI >> goes to low power mode. And then QRTR MHI driver could decide not to >> suspend/resume if low power mode is notified. >> >> Your thoughts? >> > > I'd rather query the MHI state of the device in suspend/resume callback using > mhi_get_mhi_state(mhi_dev->mhi_cntrl) and if the device is found to be in M3 > (suspend) state, then I'd skip prepare/unprepare part. > > Because this makes it clear that, if the device is in suspend state, then no > need for the client drivers to unprepare/prepare the channels. > Sounds reasonable, will do accordingly in v3. > - Mani >