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

Suman Anna
2020-03-05T00:13:51Z

On 3/4/20 3:35 PM, Mathieu Poirier wrote:
> 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().

Yeah, we can add them like in the regular suspend/resume functions.

regards
Suman

>
>> + 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
>>
>> --
>> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki