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Message-ID: <CANLsYkwZfLM2qbaPkWnAKZHWrF0UgY_ApDT6yjJ=HAadA2azsQ@mail.gmail.com>
Date: Thu, 29 Jul 2021 10:14:43 -0600
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Mike Leach <mike.leach@...aro.org>
Cc: linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
Coresight ML <coresight@...ts.linaro.org>,
"Suzuki K. Poulose" <suzuki.poulose@....com>,
Yabin Cui <yabinc@...gle.com>, Leo Yan <leo.yan@...aro.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Tingwei Zhang <tingwei@...eaurora.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v9 05/10] coresight: syscfg: Add API to activate and
enable configurations
[...]
> > > +
> > > +/**
> > > + * cscfg_csdev_enable_active_config - Enable matching active configuration for device.
> > > + *
> > > + * Enables the configuration selected by @cfg_hash if the configuration is supported
> > > + * on the device and has been activated.
> > > + *
> > > + * If active and supported the CoreSight device @csdev will be programmed with the
> > > + * configuration, using @preset parameters.
> > > + *
> > > + * Should be called before driver hardware enable for the requested device, prior to
> > > + * programming and enabling the physical hardware.
> > > + *
> > > + * @csdev: CoreSight device to program.
> > > + * @cfg_hash: Selector for the configuration.
> > > + * @preset: Preset parameter values to use, 0 for current / default values.
> > > + */
> > > +int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
> > > + unsigned long cfg_hash, int preset)
> > > +{
> > > + struct cscfg_config_csdev *config_csdev_active = NULL, *config_csdev_item;
> > > + const struct cscfg_config_desc *config_desc;
> > > + unsigned long flags;
> > > + int err = 0;
> > > +
> > > + /* quickly check global count */
> > > + if (!atomic_read(&cscfg_mgr->sys_active_cnt))
> > > + return 0;
> > > +
> > > + /* look for matching config - set in_enable flag if found */
> >
> > The second part of this comment no longer applies.
> >
>
> You are right - sorry missed that!
>
> > > + spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
> > > + list_for_each_entry(config_csdev_item, &csdev->config_csdev_list, node) {
> > > + config_desc = config_csdev_item->config_desc;
> > > + if ((atomic_read(&config_desc->active_cnt)) &&
> > > + ((unsigned long)config_desc->event_ea->var == cfg_hash)) {
> > > + config_csdev_active = config_csdev_item;
> > > + csdev->active_cscfg_ctxt = (void *)config_csdev_active;
> > > + break;
> > > + }
> > > + }
> > > + spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
> > > +
> > > + /*
> > > + * If found, attempt to enable
> > > + */
> > > + if (config_csdev_active) {
> > > + /*
> > > + * Call the generic routine that will program up the internal
> > > + * driver structures prior to programming up the hardware.
> > > + * This routine takes the driver spinlock saved in the configs.
> > > + */
> > > + err = cscfg_csdev_enable_config(config_csdev_active, preset);
> > > + if (!err) {
> > > + /*
> > > + * Successful programming. Check the active_cscfg_ctxt
> > > + * pointer to ensure no pre-emption disabled it via
> > > + * cscfg_csdev_disable_active_config() before
> > > + * we could start.
> > > + *
> > > + * Set enabled if OK, err if not.
> > > + */
> > > + spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
> > > + if (csdev->active_cscfg_ctxt)
> > > + config_csdev_active->enabled = true;
> > > + else
> > > + err = -EBUSY;
> > > + spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
> > > + }
> >
> > This is much better. I spent some time trying to break the heuristic and I
> > can't. I intend to re-apply this set to give it as much exposure as possible but
> > want to see the above comment fixed. I will do that locally though to avoid
> > having to deal with another revision. What do you think of:
> >
> > /*
> > * Look for a matching configuration - set the active configuration
> > * context if found.
> > */
> >
>
> That looks fin to me
>
> Thanks
I have applied this set.
>
> Mike
>
>
> > Thanks,
> > Mathieu
> >
> > > + }
> > > + return err;
> > > +}
> > > +EXPORT_SYMBOL_GPL(cscfg_csdev_enable_active_config);
> > > +
> > > +/**
> > > + * cscfg_csdev_disable_active_config - disable an active config on the device.
> > > + *
> > > + * Disables the active configuration on the CoreSight device @csdev.
> > > + * Disable will save the values of any registers marked in the configurations
> > > + * as save on disable.
> > > + *
> > > + * Should be called after driver hardware disable for the requested device,
> > > + * after disabling the physical hardware and reading back registers.
> > > + *
> > > + * @csdev: The CoreSight device.
> > > + */
> > > +void cscfg_csdev_disable_active_config(struct coresight_device *csdev)
> > > +{
> > > + struct cscfg_config_csdev *config_csdev;
> > > + unsigned long flags;
> > > +
> > > + /*
> > > + * Check if we have an active config, and that it was successfully enabled.
> > > + * If it was not enabled, we have no work to do, otherwise mark as disabled.
> > > + * Clear the active config pointer.
> > > + */
> > > + spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
> > > + config_csdev = (struct cscfg_config_csdev *)csdev->active_cscfg_ctxt;
> > > + if (config_csdev) {
> > > + if (!config_csdev->enabled)
> > > + config_csdev = NULL;
> > > + else
> > > + config_csdev->enabled = false;
> > > + }
> > > + csdev->active_cscfg_ctxt = NULL;
> > > + spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
> > > +
> > > + /* true if there was an enabled active config */
> > > + if (config_csdev)
> > > + cscfg_csdev_disable_config(config_csdev);
> > > +}
> > > +EXPORT_SYMBOL_GPL(cscfg_csdev_disable_active_config);
> > > +
> > > /* Initialise system configuration management device. */
> > >
> > > struct device *cscfg_device(void)
> > > @@ -536,6 +747,7 @@ int __init cscfg_init(void)
> > > INIT_LIST_HEAD(&cscfg_mgr->csdev_desc_list);
> > > INIT_LIST_HEAD(&cscfg_mgr->feat_desc_list);
> > > INIT_LIST_HEAD(&cscfg_mgr->config_desc_list);
> > > + atomic_set(&cscfg_mgr->sys_active_cnt, 0);
> > >
> > > dev_info(cscfg_device(), "CoreSight Configuration manager initialised");
> > > return 0;
> > > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h
> > > index 5bcae3b374c6..a52775890670 100644
> > > --- a/drivers/hwtracing/coresight/coresight-syscfg.h
> > > +++ b/drivers/hwtracing/coresight/coresight-syscfg.h
> > > @@ -24,12 +24,14 @@
> > > * @csdev_desc_list: List of coresight devices registered with the configuration manager.
> > > * @feat_desc_list: List of feature descriptors to load into registered devices.
> > > * @config_desc_list: List of system configuration descriptors to load into registered devices.
> > > + * @sys_active_cnt: Total number of active config descriptor references.
> > > */
> > > struct cscfg_manager {
> > > struct device dev;
> > > struct list_head csdev_desc_list;
> > > struct list_head feat_desc_list;
> > > struct list_head config_desc_list;
> > > + atomic_t sys_active_cnt;
> > > };
> > >
> > > /* get reference to dev in cscfg_manager */
> > > @@ -61,5 +63,11 @@ int cscfg_load_config_sets(struct cscfg_config_desc **cfg_descs,
> > > int cscfg_register_csdev(struct coresight_device *csdev, u32 match_flags,
> > > struct cscfg_csdev_feat_ops *ops);
> > > void cscfg_unregister_csdev(struct coresight_device *csdev);
> > > +int cscfg_activate_config(unsigned long cfg_hash);
> > > +void cscfg_deactivate_config(unsigned long cfg_hash);
> > > +void cscfg_csdev_reset_feats(struct coresight_device *csdev);
> > > +int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
> > > + unsigned long cfg_hash, int preset);
> > > +void cscfg_csdev_disable_active_config(struct coresight_device *csdev);
> > >
> > > #endif /* CORESIGHT_SYSCFG_H */
> > > diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> > > index 16544ae2b532..93a2922b7653 100644
> > > --- a/include/linux/coresight.h
> > > +++ b/include/linux/coresight.h
> > > @@ -223,6 +223,7 @@ struct coresight_sysfs_link {
> > > * @feature_csdev_list: List of complex feature programming added to the device.
> > > * @config_csdev_list: List of system configurations added to the device.
> > > * @cscfg_csdev_lock: Protect the lists of configurations and features.
> > > + * @active_cscfg_ctxt: Context information for current active system configuration.
> > > */
> > > struct coresight_device {
> > > struct coresight_platform_data *pdata;
> > > @@ -248,6 +249,7 @@ struct coresight_device {
> > > struct list_head feature_csdev_list;
> > > struct list_head config_csdev_list;
> > > spinlock_t cscfg_csdev_lock;
> > > + void *active_cscfg_ctxt;
> > > };
> > >
> > > /*
> > > --
> > > 2.17.1
> > >
>
>
>
> --
> Mike Leach
> Principal Engineer, ARM Ltd.
> Manchester Design Centre. UK
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