Messages in this thread | | | Date | Fri, 14 Sep 2018 18:23:34 +0530 | From | Sibi Sankar <> | Subject | Re: [PATCH v3 2/2] PM / devfreq: Add devfreq driver for interconnect bandwidth voting |
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Hi Saravana,
On 2018-08-02 06:27, Saravana Kannan wrote: > This driver registers itself as a devfreq device that allows devfreq > governors to make bandwidth votes for an interconnect path. This allows > applying various policies for different interconnect paths using > devfreq > governors. > > Example uses: > * Use the devfreq performance governor to set the CPU to DDR > interconnect > path for maximum performance. > * Use the devfreq performance governor to set the GPU to DDR > interconnect > path for maximum performance. > * Use the CPU frequency to device frequency mapping governor to scale > the > DDR frequency based on the needs of the CPUs' current frequency. > > Signed-off-by: Saravana Kannan <skannan@codeaurora.org> > --- > Documentation/devicetree/bindings/devfreq/icbw.txt | 21 ++++ > drivers/devfreq/Kconfig | 13 +++ > drivers/devfreq/Makefile | 1 + > drivers/devfreq/devfreq_icbw.c | 116 > +++++++++++++++++++++ > 4 files changed, 151 insertions(+) > create mode 100644 Documentation/devicetree/bindings/devfreq/icbw.txt > create mode 100644 drivers/devfreq/devfreq_icbw.c > > diff --git a/Documentation/devicetree/bindings/devfreq/icbw.txt > b/Documentation/devicetree/bindings/devfreq/icbw.txt > new file mode 100644 > index 0000000..36cf045 > --- /dev/null > +++ b/Documentation/devicetree/bindings/devfreq/icbw.txt > @@ -0,0 +1,21 @@ > +Interconnect bandwidth device > + > +icbw is a device that represents an interconnect path that connects > two > +devices. This device is typically used to vote for BW requirements > between > +two devices. Eg: CPU to DDR, GPU to DDR, etc > + > +Required properties: > +- compatible: Must be "devfreq-icbw" > +- interconnects: Pairs of phandles and interconnect provider specifier > + to denote the edge source and destination ports of > + the interconnect path. See also: > + Documentation/devicetree/bindings/interconnect/interconnect.txt > +- interconnect-names: Must have one entry with the name "path". > + > +Example: > + > + qcom,cpubw { > + compatible = "devfreq-icbw"; > + interconnects = <&snoc MASTER_APSS_1 &bimc SLAVE_EBI_CH0>; > + interconnect-names = "path"; > + }; > diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig > index 3d9ae68..590370e 100644 > --- a/drivers/devfreq/Kconfig > +++ b/drivers/devfreq/Kconfig > @@ -121,6 +121,19 @@ config ARM_RK3399_DMC_DEVFREQ > It sets the frequency for the memory controller and reads > the usage counts > from hardware. > > +config DEVFREQ_ICBW > + bool "DEVFREQ device for making bandwidth votes on interconnect > paths" > + select DEVFREQ_GOV_PERFORMANCE > + select DEVFREQ_GOV_POWERSAVE > + select DEVFREQ_GOV_USERSPACE > + default n > + help > + Different devfreq governors use this devfreq device to make > + bandwidth votes for interconnect paths between different devices > + (Eg: CPU to DDR, GPU to DDR, etc). This driver provides a generic > + interface so that the devfreq governors can be shared across SoCs > + and architectures. > + > source "drivers/devfreq/event/Kconfig" > > endif # PM_DEVFREQ > diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile > index e9dc3e9..b302c5cf 100644 > --- a/drivers/devfreq/Makefile > +++ b/drivers/devfreq/Makefile > @@ -12,6 +12,7 @@ obj-$(CONFIG_DEVFREQ_GOV_CPUFREQ_MAP) += > governor_cpufreq_map.o > obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ) += exynos-bus.o > obj-$(CONFIG_ARM_RK3399_DMC_DEVFREQ) += rk3399_dmc.o > obj-$(CONFIG_ARM_TEGRA_DEVFREQ) += tegra-devfreq.o > +obj-$(CONFIG_DEVFREQ_ICBW) += devfreq_icbw.o > > # DEVFREQ Event Drivers > obj-$(CONFIG_PM_DEVFREQ_EVENT) += event/ > diff --git a/drivers/devfreq/devfreq_icbw.c > b/drivers/devfreq/devfreq_icbw.c > new file mode 100644 > index 0000000..231fb21 > --- /dev/null > +++ b/drivers/devfreq/devfreq_icbw.c > @@ -0,0 +1,116 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (c) 2013-2014, 2018, The Linux Foundation. All rights > reserved. > + */ > + > +#define pr_fmt(fmt) "icbw: " fmt > + > +#include <linux/kernel.h> > +#include <linux/module.h> > +#include <linux/init.h> > +#include <linux/err.h> > +#include <linux/errno.h> > +#include <linux/mutex.h> > +#include <linux/devfreq.h> > +#include <linux/platform_device.h> > +#include <linux/of.h> > +#include <linux/interconnect.h> > + > +struct dev_data { > + struct icc_path *path; > + u32 cur_ab; > + u32 cur_pb; > + unsigned long gov_ab; > + struct devfreq *df; > + struct devfreq_dev_profile dp; > +}; > + > +static int icbw_target(struct device *dev, unsigned long *freq, u32 > flags) > +{ > + struct dev_data *d = dev_get_drvdata(dev); > + int ret; > + u32 new_pb = *freq, new_ab = d->gov_ab; > + > + if (d->cur_pb == new_pb && d->cur_ab == new_ab) > + return 0; > + > + dev_dbg(dev, "BW KBps: AB: %u PB: %u\n", new_ab, new_pb); > + > + ret = icc_set(d->path, new_ab, new_pb); > + if (ret) { > + dev_err(dev, "bandwidth request failed (%d)\n", ret); > + } else { > + d->cur_pb = new_pb; > + d->cur_ab = new_ab; > + } > + > + return ret; > +} > + > +static int icbw_get_dev_status(struct device *dev, > + struct devfreq_dev_status *stat) > +{ > + struct dev_data *d = dev_get_drvdata(dev); > + > + stat->private_data = &d->gov_ab; > + return 0; > +} > + > +static int devfreq_icbw_probe(struct platform_device *pdev) > +{ > + struct device *dev = &pdev->dev; > + struct dev_data *d; > + struct devfreq_dev_profile *p; > + > + d = devm_kzalloc(dev, sizeof(*d), GFP_KERNEL); > + if (!d) > + return -ENOMEM; > + dev_set_drvdata(dev, d); > + > + p = &d->dp; > + p->polling_ms = 50; > + p->target = icbw_target; > + p->get_dev_status = icbw_get_dev_status; > + > + d->path = of_icc_get(dev, "path"); > + if (IS_ERR(d->path)) { > + dev_err(dev, "Unable to register interconnect path\n"); > + return -ENODEV; > + }
The probe fails if the provider is not registered yet. Worked around it using -EPROBE_DEFER but this should probably come from of_icc_get itself.
> + > + d->df = devfreq_add_device(dev, p, "performance", NULL); > + if (IS_ERR(d->df)) { > + icc_put(d->path); > + return PTR_ERR(d->df); > + }
devfreq_add_device will fail with -EINVAL for set_table_freq, find_available_min_freq and find_available_max_freq. If you end up working your way around it, I still ended up getting multiple errors like "Couldn't update frequency transition information" after probing.
> + > + return 0; > +} > + > +static int devfreq_icbw_remove(struct platform_device *pdev) > +{ > + struct device *dev = &pdev->dev; > + struct dev_data *d = dev_get_drvdata(dev); > + > + devfreq_remove_device(d->df); > + icc_put(d->path); > + return 0; > +} > + > +static const struct of_device_id icbw_match_table[] = { > + { .compatible = "devfreq-icbw" }, > + {} > +}; > + > +static struct platform_driver icbw_driver = { > + .probe = devfreq_icbw_probe, > + .remove = devfreq_icbw_remove, > + .driver = { > + .name = "devfreq-icbw", > + .of_match_table = icbw_match_table, > + }, > +}; > + > +module_platform_driver(icbw_driver); > +MODULE_DESCRIPTION("Interconnect bandwidth voting driver"); > +MODULE_LICENSE("GPL v2");
-- -- Sibi Sankar -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.
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