| Message ID | 1650302562-30964-1-git-send-email-quic_jhugo@quicinc.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | [v4] bus: mhi: host: Wait for ready state after reset | expand |
On Mon, Apr 18, 2022 at 11:22:42AM -0600, Jeffrey Hugo wrote: > After the device has signaled the end of reset by clearing the reset bit, > it will automatically reinit MHI and the internal device structures. Once > That is done, the device will signal it has entered the ready state. > > Signaling the ready state involves sending an interrupt (MSI) to the host > which might cause IOMMU faults if it occurs at the wrong time. > > If the controller is being powered down, and possibly removed, then the > reset flow would only wait for the end of reset. At which point, the host > and device would start a race. The host may complete its reset work, and > remove the interrupt handler, which would cause the interrupt to be > disabled in the IOMMU. If that occurs before the device signals the ready > state, then the IOMMU will fault since it blocked an interrupt. While > harmless, the fault would appear like a serious issue has occurred so let's > silence it by making sure the device hits the ready state before the host > completes its reset processing. > > Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com> > Reviewed-by: Hemant Kumar <quic_hemantk@quicinc.com> > Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> Applied to mhi-next! Thanks, Mani > --- > > v4: > Cleanup email domain change > > v3: > Rebase and use dev_err over dev_warn > > v2: > Fix subject and remove use of cur_state > > drivers/bus/mhi/host/pm.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/bus/mhi/host/pm.c b/drivers/bus/mhi/host/pm.c > index 3d90b8e..c000a92 100644 > --- a/drivers/bus/mhi/host/pm.c > +++ b/drivers/bus/mhi/host/pm.c > @@ -476,6 +476,15 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl) > * hence re-program it > */ > mhi_write_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_INTVEC, 0); > + > + if (!MHI_IN_PBL(mhi_get_exec_env(mhi_cntrl))) { > + /* wait for ready to be set */ > + ret = mhi_poll_reg_field(mhi_cntrl, mhi_cntrl->regs, > + MHISTATUS, > + MHISTATUS_READY_MASK, 1, 25000); > + if (ret) > + dev_err(dev, "Device failed to enter READY state\n"); > + } > } > > dev_dbg(dev, > -- > 2.7.4 >
diff --git a/drivers/bus/mhi/host/pm.c b/drivers/bus/mhi/host/pm.c index 3d90b8e..c000a92 100644 --- a/drivers/bus/mhi/host/pm.c +++ b/drivers/bus/mhi/host/pm.c @@ -476,6 +476,15 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl) * hence re-program it */ mhi_write_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_INTVEC, 0); + + if (!MHI_IN_PBL(mhi_get_exec_env(mhi_cntrl))) { + /* wait for ready to be set */ + ret = mhi_poll_reg_field(mhi_cntrl, mhi_cntrl->regs, + MHISTATUS, + MHISTATUS_READY_MASK, 1, 25000); + if (ret) + dev_err(dev, "Device failed to enter READY state\n"); + } } dev_dbg(dev,