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SubjectRe: [PATCH v1 07/10] bus: mhi: core: Move to SYS_ERROR regardless of RDDM capability
On Fri, Sep 18, 2020 at 07:02:32PM -0700, Bhaumik Bhatt wrote:
> In some cases, the entry of device to RDDM execution environment
> can occur after a significant amount of time has elapsed after the
> SYS_ERROR state change event has arrived. This can result in scenarios
> where users of the MHI bus are unaware of the error state of the

Who are all the users of MHI bus? Client drivers?

> device. Hence, moving the MHI bus to a SYS_ERROR detected state will
> prevent further client activity and wait for the RDDM entry.
>
> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
> ---
> drivers/bus/mhi/core/main.c | 24 ++++++++++++++++--------
> 1 file changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index 2cff5dd..1c8e332 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -376,6 +376,7 @@ irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
> enum mhi_state state = MHI_STATE_MAX;
> enum mhi_pm_state pm_state = 0;
> enum mhi_ee_type ee = 0;
> + bool handle_rddm = false;
>
> write_lock_irq(&mhi_cntrl->pm_lock);
> if (!MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state)) {
> @@ -400,6 +401,17 @@ irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
> /* If device supports RDDM don't bother processing SYS error */
> if (mhi_cntrl->rddm_image) {
> if (mhi_cntrl->ee == MHI_EE_RDDM && mhi_cntrl->ee != ee) {
> + /* prevent clients from queueing any more packets */
> + write_lock_irq(&mhi_cntrl->pm_lock);
> + pm_state = mhi_tryset_pm_state(mhi_cntrl,
> + MHI_PM_SYS_ERR_DETECT);

The condition above already moves MHI to MHI_PM_SYS_ERR_DETECT if the state
is MHI_STATE_SYS_ERR. Why are you doing it here again?

Thanks,
Mani

> + if (pm_state == MHI_PM_SYS_ERR_DETECT)
> + handle_rddm = true;
> + write_unlock_irq(&mhi_cntrl->pm_lock);
> + }
> +
> + if (handle_rddm) {
> + dev_err(dev, "RDDM event occurred!\n");
> mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_EE_RDDM);
> wake_up_all(&mhi_cntrl->state_event);
> }
> @@ -733,19 +745,15 @@ int mhi_process_ctrl_ev_ring(struct mhi_controller *mhi_cntrl,
> break;
> case MHI_STATE_SYS_ERR:
> {
> - enum mhi_pm_state new_state;
> -
> - /* skip SYS_ERROR handling if RDDM supported */
> - if (mhi_cntrl->ee == MHI_EE_RDDM ||
> - mhi_cntrl->rddm_image)
> - break;
> + enum mhi_pm_state state = MHI_PM_STATE_MAX;
>
> dev_dbg(dev, "System error detected\n");
> write_lock_irq(&mhi_cntrl->pm_lock);
> - new_state = mhi_tryset_pm_state(mhi_cntrl,
> + if (mhi_cntrl->ee != MHI_EE_RDDM)
> + state = mhi_tryset_pm_state(mhi_cntrl,
> MHI_PM_SYS_ERR_DETECT);
> write_unlock_irq(&mhi_cntrl->pm_lock);
> - if (new_state == MHI_PM_SYS_ERR_DETECT)
> + if (state == MHI_PM_SYS_ERR_DETECT)
> mhi_pm_sys_err_handler(mhi_cntrl);
> break;
> }
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>

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