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SubjectRe: [PATCH 1/3] bus: mhi: core: Handle syserr during power_up
On Mon, Apr 06, 2020 at 03:04:35PM -0600, Jeffrey Hugo wrote:
> The MHI device may be in the syserr state when we attempt to init it in
> power_up(). Since we have no local state, the handling is simple -
> reset the device and wait for it to transition out of the reset state.
>
> Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
> ---
> drivers/bus/mhi/core/pm.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> index 52690cb..cd6ba23 100644
> --- a/drivers/bus/mhi/core/pm.c
> +++ b/drivers/bus/mhi/core/pm.c
> @@ -9,6 +9,7 @@
> #include <linux/dma-direction.h>
> #include <linux/dma-mapping.h>
> #include <linux/interrupt.h>
> +#include <linux/iopoll.h>
> #include <linux/list.h>
> #include <linux/mhi.h>
> #include <linux/module.h>
> @@ -760,6 +761,7 @@ static void mhi_deassert_dev_wake(struct mhi_controller *mhi_cntrl,
>
> int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
> {
> + enum mhi_state state;
> enum mhi_ee_type current_ee;
> enum dev_st_transition next_state;
> struct device *dev = &mhi_cntrl->mhi_dev->dev;
> @@ -829,6 +831,24 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
> goto error_bhi_offset;
> }
>
> + state = mhi_get_mhi_state(mhi_cntrl);
> + if (state == MHI_STATE_SYS_ERR) {
> + mhi_set_mhi_state(mhi_cntrl, MHI_STATE_RESET);
> + ret = readl_poll_timeout(mhi_cntrl->regs + MHICTRL, val,
> + !(val & MHICTRL_RESET_MASK), 1000,

Hmm. Do we really need a max 1ms delay between each read? I'd prefer to have
100ns to reduce the wait time.

> + mhi_cntrl->timeout_ms * 1000);
> + if (ret) {
> + dev_info(dev, "Failed to reset syserr\n");

dev_info(dev, "Failed to reset MHI due to syserr state\n"); ?

Thanks,
Mani

> + goto error_bhi_offset;
> + }
> +
> + /*
> + * device cleares INTVEC as part of RESET processing,
> + * re-program it
> + */
> + mhi_write_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_INTVEC, 0);
> + }
> +
> /* Transition to next state */
> next_state = MHI_IN_PBL(current_ee) ?
> DEV_ST_TRANSITION_PBL : DEV_ST_TRANSITION_READY;
> --
> Qualcomm Technologies, Inc. is a member of the
> Code Aurora Forum, a Linux Foundation Collaborative Project.

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