On Wed, 23 Feb 2022, Ricardo Martinez wrote:
> From: Haijun Liu <haijun.liu@xxxxxxxxxxxx>
>
> Introduce the mechanism to lock/unlock the device 'deep sleep' mode.
> When the PCIe link state is L1.2 or L2, the host side still can keep
> the device is in D0 state from the host side point of view. At the same
> time, if the device's 'deep sleep' mode is unlocked, the device will
> go to 'deep sleep' while it is still in D0 state on the host side.
>
> Signed-off-by: Haijun Liu <haijun.liu@xxxxxxxxxxxx>
> Signed-off-by: Chandrashekar Devegowda <chandrashekar.devegowda@xxxxxxxxx>
> Co-developed-by: Ricardo Martinez <ricardo.martinez@xxxxxxxxxxxxxxx>
> Signed-off-by: Ricardo Martinez <ricardo.martinez@xxxxxxxxxxxxxxx>
> ---
> +int t7xx_pci_sleep_disable_complete(struct t7xx_pci_dev *t7xx_dev)
> +{
> + struct device *dev = &t7xx_dev->pdev->dev;
> + int ret;
> +
> + ret = wait_for_completion_timeout(&t7xx_dev->sleep_lock_acquire,
> + msecs_to_jiffies(PM_SLEEP_DIS_TIMEOUT_MS));
> + if (!ret)
> + dev_err_ratelimited(dev, "Resource wait complete timed out\n");
> +
> + return ret;
> +}
> +
> +/**
> + * t7xx_pci_disable_sleep() - Disable deep sleep capability.
> + * @t7xx_dev: MTK device.
> + *
> + * Lock the deep sleep capability, note that the device can still go into deep sleep
> + * state while device is in D0 state, from the host's point-of-view.
> + *
> + * If device is in deep sleep state, wake up the device and disable deep sleep capability.
> + */
> +void t7xx_pci_disable_sleep(struct t7xx_pci_dev *t7xx_dev)
> +{
> + unsigned long flags;
> +
> + if (atomic_read(&t7xx_dev->md_pm_state) < MTK_PM_RESUMED) {
> + atomic_inc(&t7xx_dev->sleep_disable_count);
> + complete_all(&t7xx_dev->sleep_lock_acquire);
> + return;
> + }
> +
> + spin_lock_irqsave(&t7xx_dev->md_pm_lock, flags);
> + if (atomic_inc_return(&t7xx_dev->sleep_disable_count) == 1) {
> + u32 deep_sleep_enabled;
> +
> + reinit_completion(&t7xx_dev->sleep_lock_acquire);
You might want to check that there's a mechanism that prevents this
racing with wait_for_completion_timeout() in t7xx_pci_sleep_disable_complete().
I couldn't prove it myself but there are probably aspect in the PM side of
things I wasn't able to take fully into account (that is, which call
paths are not possible to occur).
> + t7xx_dev_set_sleep_capability(t7xx_dev, false);
> +
> + deep_sleep_enabled = ioread32(IREG_BASE(t7xx_dev) + T7XX_PCIE_RESOURCE_STATUS);
> + deep_sleep_enabled &= T7XX_PCIE_RESOURCE_STS_MSK;
> + if (deep_sleep_enabled) {
> + spin_unlock_irqrestore(&t7xx_dev->md_pm_lock, flags);
> + complete_all(&t7xx_dev->sleep_lock_acquire);
> + return;
> + }
> +
> + t7xx_mhccif_h2d_swint_trigger(t7xx_dev, H2D_CH_DS_LOCK);
> + }
> + spin_unlock_irqrestore(&t7xx_dev->md_pm_lock, flags);
> +}
--
i.
