Messages in this thread | | | Date | Wed, 10 Mar 2021 14:58:39 -0800 | From | Bhaumik Bhatt <> | Subject | Re: [PATCH v3 2/3] bus: mhi: core: Move to polling method to wait for MHI ready |
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On 2021-03-10 11:02 AM, Jeffrey Hugo wrote: > On 2/23/2021 8:44 PM, Bhaumik Bhatt wrote: >> In certain devices, it is likely that there is no incoming MHI >> interrupt for a transition to MHI READY state. One such example >> is the move from Pass Through to an SBL or AMSS execution >> environment. In order to facilitate faster bootup times as there >> is no need to wait until timeout_ms completes, MHI host can poll >> every 25 milliseconds to check if device has entered MHI READY >> until a maximum timeout of twice the timeout_ms is reached. >> >> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org> >> --- >> drivers/bus/mhi/core/pm.c | 31 ++++++++++++++----------------- >> 1 file changed, 14 insertions(+), 17 deletions(-) >> >> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c >> index 681960c..5fe33d4 100644 >> --- a/drivers/bus/mhi/core/pm.c >> +++ b/drivers/bus/mhi/core/pm.c >> @@ -153,34 +153,31 @@ static void mhi_toggle_dev_wake(struct >> mhi_controller *mhi_cntrl) >> /* Handle device ready state transition */ >> int mhi_ready_state_transition(struct mhi_controller *mhi_cntrl) >> { >> - void __iomem *base = mhi_cntrl->regs; >> struct mhi_event *mhi_event; >> enum mhi_pm_state cur_state; >> struct device *dev = &mhi_cntrl->mhi_dev->dev; >> - u32 reset = 1, ready = 0; >> int ret, i; >> - /* Wait for RESET to be cleared and READY bit to be set by the >> device */ >> - wait_event_timeout(mhi_cntrl->state_event, >> - MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state) || >> - mhi_read_reg_field(mhi_cntrl, base, MHICTRL, >> - MHICTRL_RESET_MASK, >> - MHICTRL_RESET_SHIFT, &reset) || >> - mhi_read_reg_field(mhi_cntrl, base, MHISTATUS, >> - MHISTATUS_READY_MASK, >> - MHISTATUS_READY_SHIFT, &ready) || >> - (!reset && ready), >> - msecs_to_jiffies(mhi_cntrl->timeout_ms)); >> - >> /* Check if device entered error state */ >> if (MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state)) { >> dev_err(dev, "Device link is not accessible\n"); >> return -EIO; >> } >> - /* Timeout if device did not transition to ready state */ >> - if (reset || !ready) { >> - dev_err(dev, "Device Ready timeout\n"); >> + /* Wait for RESET to be cleared and READY bit to be set by the >> device */ >> + ret = mhi_poll_reg_field(mhi_cntrl, mhi_cntrl->regs, MHICTRL, >> + MHICTRL_RESET_MASK, MHICTRL_RESET_SHIFT, 0, >> + 25000); >> + if (ret) { >> + dev_err(dev, "Device failed to clear MHI Reset\n"); >> + return -ETIMEDOUT; >> + } >> + >> + ret = mhi_poll_reg_field(mhi_cntrl, mhi_cntrl->regs, MHISTATUS, >> + MHISTATUS_READY_MASK, MHISTATUS_READY_SHIFT, 1, >> + 25000); > > You use the magic number "25000" twice here. Its my understanding > that the preference is to inline a magic number if its used in one > spot, but use a macro if its used more than that. > > Both uses are confined to this function, and in close proximity, so > chances that one gets updated without the other seem minimal, so this > feels like a borderline case. I don't know if Mani has an opinion > here. > > I'd probably err on the side of making a macro or a single variable. > If not, I think some comments explaining the value are warranted > (should comment the macro as well). > I think just using a variable would be good enough here. I can add a comment when defining the interval variable. >> + if (ret) { >> + dev_err(dev, "Device failed to enter MHI Ready\n"); >> return -ETIMEDOUT; >> } >>
Thanks, Bhaumik --- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
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