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    SubjectRe: [PATCH v4] bus: mhi: host: Skip MHI reset if device is in RDDM
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    On 5/19/2023 9:51 PM, Manivannan Sadhasivam wrote:
    > On Thu, May 18, 2023 at 02:22:39PM +0800, Qiang Yu wrote:
    >> In RDDM EE, device can not process MHI reset issued by host. In case of MHI
    >> power off, host is issuing MHI reset and polls for it to get cleared until
    >> it times out. Since this timeout can not be avoided in case of RDDM, skip
    >> the MHI reset in this scenarios.
    >>
    >> Cc: <stable@vger.kernel.org>
    >> Fixes: a6e2e3522f29 ("bus: mhi: core: Add support for PM state transitions")
    >> Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com>
    >> Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
    >> ---
    >> v1->v2: use ~75 columns in commit text, add Fixes tag
    >> v2->v3: update Fixes tag
    >> v3->v4: add review tag and CC stable
    >>
    >> drivers/bus/mhi/host/pm.c | 5 +++++
    >> 1 file changed, 5 insertions(+)
    >>
    >> diff --git a/drivers/bus/mhi/host/pm.c b/drivers/bus/mhi/host/pm.c
    >> index 0834590..8a4362d 100644
    >> --- a/drivers/bus/mhi/host/pm.c
    >> +++ b/drivers/bus/mhi/host/pm.c
    >> @@ -470,6 +470,10 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl)
    >>
    >> /* Trigger MHI RESET so that the device will not access host memory */
    >> if (!MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state)) {
    >> + /* Skip MHI RESET if in RDDM state */
    >> + if (mhi_cntrl->rddm_image && mhi_get_exec_env(mhi_cntrl) == MHI_EE_RDDM)
    > Do we really need to check for rddm_image? Wouldn't the EE check sufficient
    > enough?
    >
    > In that case, the check can be moved to the prior if condition.
    >
    > - Mani

    If rddm_image is NULL, that means this device does not support RDDM. In this case, it is unnecessary to access MMIO register.

    >> + goto skip_mhi_reset;
    >> +
    >> dev_dbg(dev, "Triggering MHI Reset in device\n");
    >> mhi_set_mhi_state(mhi_cntrl, MHI_STATE_RESET);
    >>
    >> @@ -495,6 +499,7 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl)
    >> }
    >> }
    >>
    >> +skip_mhi_reset:
    >> dev_dbg(dev,
    >> "Waiting for all pending event ring processing to complete\n");
    >> mhi_event = mhi_cntrl->mhi_event;
    >> --
    >> 2.7.4
    >>
    >>

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