Re: [PATCHv7 12/15] remoteproc/omap: Add support for runtime auto-suspend/resume

Mathieu Poirier
2020-03-04T21:35:10Z

On Fri, Feb 21, 2020 at 12:19:33PM +0200, Tero Kristo wrote:
> From: Suman Anna <s-anna@ti.com>
>
> This patch enhances the PM support in the OMAP remoteproc driver to
> support the runtime auto-suspend. A remoteproc may not be required to
> be running all the time, and typically will need to be active only
> during certain usecases. As such, to save power, it should be turned
> off during potential long periods of inactivity between usecases.
> This suspend and resume of the device is a relatively heavy process
> in terms of latencies, so a remoteproc should be suspended only after
> a certain period of prolonged inactivity. The OMAP remoteproc driver
> leverages the runtime pm framework's auto_suspend feature to accomplish
> this functionality. This feature is automatically enabled when a remote
> processor has successfully booted. The 'autosuspend_delay_ms' for each
> device dictates the inactivity period/time to wait for before
> suspending the device.
>
> The runtime auto-suspend design relies on marking the last busy time
> on every communication (virtqueue kick) to and from the remote processor.
> When there has been no activity for 'autosuspend_delay_ms' time, the
> runtime PM framework invokes the driver's runtime pm suspend callback
> to suspend the device. The remote processor will be woken up on the
> initiation of the next communication message through the runtime pm
> resume callback. The current auto-suspend design also allows a remote
> processor to deny a auto-suspend attempt, if it wishes to, by sending a
> NACK response to the initial suspend request message sent to the remote
> processor as part of the suspend process. The auto-suspend request is
> also only attempted if the remote processor is idled and in standby at
> the time of inactivity timer expiry. This choice is made to avoid
> unnecessary messaging, and the auto-suspend is simply rescheduled to
> be attempted again after a further lapse of autosuspend_delay_ms.
>
> The runtime pm callbacks functionality in this patch reuses most of the
> core logic from the suspend/resume support code, and make use of an
> additional auto_suspend flag to differentiate the logic in common code
> from system suspend. The system suspend/resume sequences are also updated
> to reflect the proper pm_runtime statuses, and also to really perform a
> suspend/resume only if the remoteproc has not been auto-suspended at the
> time of request. The remote processor is left in suspended state on a
> system resume if it has been auto-suspended before, and will be woken up
> only when a usecase needs to run.
>
> The OMAP remoteproc driver currently uses a default value of 10 seconds
> for all OMAP remoteprocs, and a different value can be chosen either by
> choosing a positive value for the 'ti,autosuspend-delay-ms' under DT or
> by updating the 'autosuspend_delay_ms' field at runtime through the
> sysfs interface. A negative value is equivalent to disabling the runtime
> suspend.
> Eg: To use 25 seconds for IPU2 on DRA7xx,
> echo 25000 > /sys/bus/platform/devices/55020000.ipu/power/autosuspend_delay_ms
>
> The runtime suspend feature can also be similarly enabled or disabled by
> writing 'auto' or 'on' to the device's 'control' power field. The default
> is enabled.
> Eg: To disable auto-suspend for IPU2 on DRA7xx SoC,
> echo on > /sys/bus/platform/devices/55020000.ipu/power/control
>
> Signed-off-by: Suman Anna <s-anna@ti.com>
> [t-kristo@ti.com: converted to use ti-sysc instead of hwmod]
> Signed-off-by: Tero Kristo <t-kristo@ti.com>
> ---
> v7:
> - fixed the broken behavior for timers during runtime suspend
> - revamped the runtime PM handling code back towards the initial
> implementation, Suman reported some issues which seemed to have
> been introduced by my attempts to clean-up the code a bit.
>
> drivers/remoteproc/omap_remoteproc.c | 202 +++++++++++++++++++++++++--
> 1 file changed, 193 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/remoteproc/omap_remoteproc.c b/drivers/remoteproc/omap_remoteproc.c
> index 0d45af1fb0e3..1ac270df4d66 100644
> --- a/drivers/remoteproc/omap_remoteproc.c
> +++ b/drivers/remoteproc/omap_remoteproc.c
> @@ -22,6 +22,7 @@
> #include <linux/of_device.h>
> #include <linux/of_reserved_mem.h>
> #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> #include <linux/dma-mapping.h>
> #include <linux/remoteproc.h>
> #include <linux/mailbox_client.h>
> @@ -37,6 +38,9 @@
> #include "omap_remoteproc.h"
> #include "remoteproc_internal.h"
>
> +/* default auto-suspend delay (ms) */
> +#define DEFAULT_AUTOSUSPEND_DELAY 10000
> +
> /**
> * struct omap_rproc_boot_data - boot data structure for the DSP omap rprocs
> * @syscon: regmap handle for the system control configuration module
> @@ -83,6 +87,8 @@ struct omap_rproc_timer {
> * @num_mems: number of internal memory regions
> * @num_timers: number of rproc timer(s)
> * @timers: timer(s) info used by rproc
> + * @autosuspend_delay: auto-suspend delay value to be used for runtime pm
> + * @need_resume: if true a resume is needed in the system resume callback
> * @rproc: rproc handle
> * @reset: reset handle
> * @pm_comp: completion primitive to sync for suspend response
> @@ -97,6 +103,8 @@ struct omap_rproc {
> int num_mems;
> int num_timers;
> struct omap_rproc_timer *timers;
> + int autosuspend_delay;
> + bool need_resume;
> struct rproc *rproc;
> struct reset_control *reset;
> struct completion pm_comp;
> @@ -407,11 +415,23 @@ static void omap_rproc_kick(struct rproc *rproc, int vqid)
> struct device *dev = rproc->dev.parent;
> int ret;
>
> + /* wake up the rproc before kicking it */
> + ret = pm_runtime_get_sync(dev);
> + if (WARN_ON(ret < 0)) {
> + dev_err(dev, "pm_runtime_get_sync() failed during kick, ret = %d\n",
> + ret);
> + pm_runtime_put_noidle(dev);
> + return;
> + }
> +
> /* send the index of the triggered virtqueue in the mailbox payload */
> ret = mbox_send_message(oproc->mbox, (void *)vqid);
> if (ret < 0)
> dev_err(dev, "failed to send mailbox message, status = %d\n",
> ret);
> +
> + pm_runtime_mark_last_busy(dev);
> + pm_runtime_put_autosuspend(dev);
> }
>
> /**
> @@ -504,6 +524,18 @@ static int omap_rproc_start(struct rproc *rproc)
> goto disable_timers;
> }
>
> + /*
> + * remote processor is up, so update the runtime pm status and
> + * enable the auto-suspend. The device usage count is incremented
> + * manually for balancing it for auto-suspend
> + */
> + pm_runtime_set_active(dev);
> + pm_runtime_use_autosuspend(dev);
> + pm_runtime_get_noresume(dev);
> + pm_runtime_enable(dev);
> + pm_runtime_mark_last_busy(dev);
> + pm_runtime_put_autosuspend(dev);
> +
> return 0;
>
> disable_timers:
> @@ -516,20 +548,52 @@ static int omap_rproc_start(struct rproc *rproc)
> /* power off the remote processor */
> static int omap_rproc_stop(struct rproc *rproc)
> {
> + struct device *dev = rproc->dev.parent;
> struct omap_rproc *oproc = rproc->priv;
> int ret;
>
> + /*
> + * cancel any possible scheduled runtime suspend by incrementing
> + * the device usage count, and resuming the device. The remoteproc
> + * also needs to be woken up if suspended, to avoid the remoteproc
> + * OS to continue to remember any context that it has saved, and
> + * avoid potential issues in misindentifying a subsequent device
> + * reboot as a power restore boot
> + */
> + ret = pm_runtime_get_sync(dev);
> + if (ret < 0) {
> + pm_runtime_put_noidle(dev);
> + return ret;
> + }
> +
> ret = reset_control_assert(oproc->reset);
> if (ret)
> - return ret;
> + goto out;
>
> ret = omap_rproc_disable_timers(rproc, true);
> if (ret)
> - return ret;
> + goto enable_device;
>
> mbox_free_channel(oproc->mbox);
>
> + /*
> + * update the runtime pm states and status now that the remoteproc
> + * has stopped
> + */
> + pm_runtime_disable(dev);
> + pm_runtime_dont_use_autosuspend(dev);
> + pm_runtime_put_noidle(dev);
> + pm_runtime_set_suspended(dev);
> +
> return 0;
> +
> +enable_device:
> + reset_control_deassert(oproc->reset);
> +out:
> + /* schedule the next auto-suspend */
> + pm_runtime_mark_last_busy(dev);
> + pm_runtime_put_autosuspend(dev);
> + return ret;
> }
>
> /**
> @@ -586,17 +650,19 @@ static bool _is_rproc_in_standby(struct omap_rproc *oproc)
>
> /* 1 sec is long enough time to let the remoteproc side suspend the device */
> #define DEF_SUSPEND_TIMEOUT 1000
> -static int _omap_rproc_suspend(struct rproc *rproc)
> +static int _omap_rproc_suspend(struct rproc *rproc, bool auto_suspend)
> {
> struct device *dev = rproc->dev.parent;
> struct omap_rproc *oproc = rproc->priv;
> unsigned long to = msecs_to_jiffies(DEF_SUSPEND_TIMEOUT);
> unsigned long ta = jiffies + to;
> + u32 suspend_msg = auto_suspend ?
> + RP_MBOX_SUSPEND_AUTO : RP_MBOX_SUSPEND_SYSTEM;
> int ret;
>
> reinit_completion(&oproc->pm_comp);
> oproc->suspend_acked = false;
> - ret = mbox_send_message(oproc->mbox, (void *)RP_MBOX_SUSPEND_SYSTEM);
> + ret = mbox_send_message(oproc->mbox, (void *)suspend_msg);
> if (ret < 0) {
> dev_err(dev, "PM mbox_send_message failed: %d\n", ret);
> return ret;
> @@ -640,32 +706,62 @@ static int _omap_rproc_suspend(struct rproc *rproc)
> goto enable_device;
> }
>
> + /*
> + * IOMMUs would have to be disabled specifically for runtime suspend.
> + * They are handled automatically through System PM callbacks for
> + * regular system suspend
> + */
> + if (auto_suspend) {
> + ret = omap_iommu_domain_deactivate(rproc->domain);
> + if (ret) {
> + dev_err(dev, "iommu domain deactivate failed %d\n",
> + ret);
> + goto enable_timers;
> + }
> + }
> +
> return 0;
>
> +enable_timers:
> + /* ignore errors on re-enabling code */
> + omap_rproc_enable_timers(rproc, false);
> enable_device:
> reset_control_deassert(oproc->reset);
> return ret;
> }
>
> -static int _omap_rproc_resume(struct rproc *rproc)
> +static int _omap_rproc_resume(struct rproc *rproc, bool auto_suspend)
> {
> struct device *dev = rproc->dev.parent;
> struct omap_rproc *oproc = rproc->priv;
> int ret;
>
> + /*
> + * IOMMUs would have to be enabled specifically for runtime resume.
> + * They would have been already enabled automatically through System
> + * PM callbacks for regular system resume
> + */
> + if (auto_suspend) {
> + ret = omap_iommu_domain_activate(rproc->domain);
> + if (ret) {
> + dev_err(dev, "omap_iommu activate failed %d\n", ret);
> + goto out;
> + }
> + }
> +
> /* boot address could be lost after suspend, so restore it */
> if (oproc->boot_data) {
> ret = omap_rproc_write_dsp_boot_addr(rproc);
> if (ret) {
> dev_err(dev, "boot address restore failed %d\n", ret);
> - goto out;
> + goto suspend_iommu;
> }
> }
>
> ret = omap_rproc_enable_timers(rproc, false);
> if (ret) {
> dev_err(dev, "enabling timers during resume failed %d\n", ret);
> - goto out;
> + goto suspend_iommu;
> }
>
> ret = reset_control_deassert(oproc->reset);
> @@ -678,6 +774,9 @@ static int _omap_rproc_resume(struct rproc *rproc)
>
> disable_timers:
> omap_rproc_disable_timers(rproc, false);
> +suspend_iommu:
> + if (auto_suspend)
> + omap_iommu_domain_deactivate(rproc->domain);
> out:
> return ret;
> }
> @@ -686,6 +785,7 @@ static int __maybe_unused omap_rproc_suspend(struct device *dev)
> {
> struct platform_device *pdev = to_platform_device(dev);
> struct rproc *rproc = platform_get_drvdata(pdev);
> + struct omap_rproc *oproc = rproc->priv;
> int ret = 0;
>
> mutex_lock(&rproc->lock);
> @@ -700,13 +800,19 @@ static int __maybe_unused omap_rproc_suspend(struct device *dev)
> goto out;
> }
>
> - ret = _omap_rproc_suspend(rproc);
> + ret = _omap_rproc_suspend(rproc, false);
> if (ret) {
> dev_err(dev, "suspend failed %d\n", ret);
> goto out;
> }
>
> + /*
> + * remoteproc is running at the time of system suspend, so remember
> + * it so as to wake it up during system resume
> + */
> + oproc->need_resume = true;
> rproc->state = RPROC_SUSPENDED;
> +
> out:
> mutex_unlock(&rproc->lock);
> return ret;
> @@ -716,6 +822,7 @@ static int __maybe_unused omap_rproc_resume(struct device *dev)
> {
> struct platform_device *pdev = to_platform_device(dev);
> struct rproc *rproc = platform_get_drvdata(pdev);
> + struct omap_rproc *oproc = rproc->priv;
> int ret = 0;
>
> mutex_lock(&rproc->lock);
> @@ -727,17 +834,86 @@ static int __maybe_unused omap_rproc_resume(struct device *dev)
> goto out;
> }
>
> - ret = _omap_rproc_resume(rproc);
> + /*
> + * remoteproc was auto-suspended at the time of system suspend,
> + * so no need to wake-up the processor (leave it in suspended
> + * state, will be woken up during a subsequent runtime_resume)
> + */
> + if (!oproc->need_resume)
> + goto out;
> +
> + ret = _omap_rproc_resume(rproc, false);
> if (ret) {
> dev_err(dev, "resume failed %d\n", ret);
> goto out;
> }
>
> + oproc->need_resume = false;
> rproc->state = RPROC_RUNNING;
> +
> + pm_runtime_mark_last_busy(dev);
> out:
> mutex_unlock(&rproc->lock);
> return ret;
> }
> +
> +static int omap_rproc_runtime_suspend(struct device *dev)
> +{
> + struct rproc *rproc = dev_get_drvdata(dev);
> + struct omap_rproc *oproc = rproc->priv;
> + int ret;
> +

Shouldn't the rproc->lock be held here? Same for omap_rproc_runtime_resume().

> + if (rproc->state == RPROC_CRASHED) {
> + dev_dbg(dev, "rproc cannot be runtime suspended when crashed!\n");
> + return -EBUSY;
> + }
> +
> + if (WARN_ON(rproc->state != RPROC_RUNNING)) {
> + dev_err(dev, "rproc cannot be runtime suspended when not running!\n");
> + return -EBUSY;
> + }
> +
> + /*
> + * do not even attempt suspend if the remote processor is not
> + * idled for runtime auto-suspend
> + */
> + if (!_is_rproc_in_standby(oproc)) {
> + ret = -EBUSY;
> + goto abort;
> + }
> +
> + ret = _omap_rproc_suspend(rproc, true);
> + if (ret)
> + goto abort;
> +
> + rproc->state = RPROC_SUSPENDED;
> + return 0;
> +
> +abort:
> + pm_runtime_mark_last_busy(dev);
> + return ret;
> +}
> +
> +static int omap_rproc_runtime_resume(struct device *dev)
> +{
> + struct rproc *rproc = dev_get_drvdata(dev);
> + int ret;
> +
> + if (WARN_ON(rproc->state != RPROC_SUSPENDED)) {
> + dev_err(dev, "rproc cannot be runtime resumed if not suspended! state=%d\n",
> + rproc->state);
> + return -EBUSY;
> + }
> +
> + ret = _omap_rproc_resume(rproc, true);
> + if (ret) {
> + dev_err(dev, "runtime resume failed %d\n", ret);
> + return ret;
> + }
> +
> + rproc->state = RPROC_RUNNING;
> + return 0;
> +}
> #endif /* CONFIG_PM */
>
> static const struct omap_rproc_mem_data ipu_mems[] = {
> @@ -983,6 +1159,12 @@ static int omap_rproc_probe(struct platform_device *pdev)
> }
>
> init_completion(&oproc->pm_comp);
> + oproc->autosuspend_delay = DEFAULT_AUTOSUSPEND_DELAY;
> +
> + of_property_read_u32(pdev->dev.of_node, "ti,autosuspend-delay-ms",
> + &oproc->autosuspend_delay);
> +
> + pm_runtime_set_autosuspend_delay(&pdev->dev, oproc->autosuspend_delay);
>
> oproc->fck = devm_clk_get(&pdev->dev, 0);
> if (IS_ERR(oproc->fck)) {
> @@ -1025,6 +1207,8 @@ static int omap_rproc_remove(struct platform_device *pdev)
>
> static const struct dev_pm_ops omap_rproc_pm_ops = {
> SET_SYSTEM_SLEEP_PM_OPS(omap_rproc_suspend, omap_rproc_resume)
> + SET_RUNTIME_PM_OPS(omap_rproc_runtime_suspend,
> + omap_rproc_runtime_resume, NULL)
> };
>
> static struct platform_driver omap_rproc_driver = {
> --
> 2.17.1
>
> --
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