On Wed, Mar 31, 2021 at 11:34:25AM -0700, 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 <bbh...@codeaurora.org>
> Reviewed-by: Loic Poulain <loic.poul...@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasi...@linaro.org>
Thanks,
Mani
> ---
> drivers/bus/mhi/core/pm.c | 34 ++++++++++++++++------------------
> 1 file changed, 16 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> index b6920a5..e4aff77 100644
> --- a/drivers/bus/mhi/core/pm.c
> +++ b/drivers/bus/mhi/core/pm.c
> @@ -153,35 +153,33 @@ 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;
> + u32 interval_us = 25000; /* poll register field every 25 milliseconds */
> 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");
> - return -ETIMEDOUT;
> + /* 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,
> + interval_us);
> + if (ret) {
> + dev_err(dev, "Device failed to clear MHI Reset\n");
> + return ret;
> + }
> +
> + ret = mhi_poll_reg_field(mhi_cntrl, mhi_cntrl->regs, MHISTATUS,
> + MHISTATUS_READY_MASK, MHISTATUS_READY_SHIFT, 1,
> + interval_us);
> + if (ret) {
> + dev_err(dev, "Device failed to enter MHI Ready\n");
> + return ret;
> }
>
> dev_dbg(dev, "Device in READY State\n");
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
