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    SubjectRe: [RFC PATCH v5 2/6] interconnect: Add generic interconnect driver for Exynos SoCs
    On Fri, May 29, 2020 at 06:31:56PM +0200, Sylwester Nawrocki wrote:
    > This patch adds a generic interconnect driver for Exynos SoCs in order
    > to provide interconnect functionality for each "samsung,exynos-bus"
    > compatible device.
    >
    > The SoC topology is a graph (or more specifically, a tree) and its
    > edges are specified using the 'samsung,interconnect-parent' in the
    > DT. Due to unspecified relative probing order, -EPROBE_DEFER may be
    > propagated to ensure that the parent is probed before its children.
    >
    > Each bus is now an interconnect provider and an interconnect node as
    > well (cf. Documentation/interconnect/interconnect.rst), i.e. every bus
    > registers itself as a node. Node IDs are not hardcoded but rather
    > assigned dynamically at runtime. This approach allows for using this
    > driver with various Exynos SoCs.
    >
    > Frequencies requested via the interconnect API for a given node are
    > propagated to devfreq using dev_pm_qos_update_request(). Please note
    > that it is not an error when CONFIG_INTERCONNECT is 'n', in which
    > case all interconnect API functions are no-op.
    >
    > Signed-off-by: Artur Świgoń <a.swigon@samsung.com>
    > Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
    >
    > Changes for v5:
    > - adjust to renamed exynos,interconnect-parent-node property,
    > - use automatically generated platform device id as the interconect
    > node id instead of a now unavailable devfreq->id field,
    > - add icc_ prefix to some variables to make the code more self-commenting,
    > - use icc_nodes_remove() instead of icc_node_del() + icc_node_destroy(),
    > - adjust to exynos,interconnect-parent-node property rename to
    > samsung,interconnect-parent,
    > - converted to a separate platform driver in drivers/interconnect.
    > ---
    > drivers/interconnect/Kconfig | 1 +
    > drivers/interconnect/Makefile | 1 +
    > drivers/interconnect/exynos/Kconfig | 6 ++
    > drivers/interconnect/exynos/Makefile | 4 +
    > drivers/interconnect/exynos/exynos.c | 185 +++++++++++++++++++++++++++++++++++
    > 5 files changed, 197 insertions(+)
    > create mode 100644 drivers/interconnect/exynos/Kconfig
    > create mode 100644 drivers/interconnect/exynos/Makefile
    > create mode 100644 drivers/interconnect/exynos/exynos.c
    >
    > diff --git a/drivers/interconnect/Kconfig b/drivers/interconnect/Kconfig
    > index 5b7204e..eca6eda 100644
    > --- a/drivers/interconnect/Kconfig
    > +++ b/drivers/interconnect/Kconfig
    > @@ -11,6 +11,7 @@ menuconfig INTERCONNECT
    >
    > if INTERCONNECT
    >
    > +source "drivers/interconnect/exynos/Kconfig"
    > source "drivers/interconnect/imx/Kconfig"
    > source "drivers/interconnect/qcom/Kconfig"
    >
    > diff --git a/drivers/interconnect/Makefile b/drivers/interconnect/Makefile
    > index 4825c28..2ba1de6 100644
    > --- a/drivers/interconnect/Makefile
    > +++ b/drivers/interconnect/Makefile
    > @@ -4,5 +4,6 @@ CFLAGS_core.o := -I$(src)
    > icc-core-objs := core.o
    >
    > obj-$(CONFIG_INTERCONNECT) += icc-core.o
    > +obj-$(CONFIG_INTERCONNECT_EXYNOS) += exynos/
    > obj-$(CONFIG_INTERCONNECT_IMX) += imx/
    > obj-$(CONFIG_INTERCONNECT_QCOM) += qcom/
    > diff --git a/drivers/interconnect/exynos/Kconfig b/drivers/interconnect/exynos/Kconfig
    > new file mode 100644
    > index 0000000..e51e52e
    > --- /dev/null
    > +++ b/drivers/interconnect/exynos/Kconfig
    > @@ -0,0 +1,6 @@
    > +# SPDX-License-Identifier: GPL-2.0-only
    > +config INTERCONNECT_EXYNOS
    > + tristate "Exynos generic interconnect driver"
    > + depends on ARCH_EXYNOS || COMPILE_TEST
    > + help
    > + Generic interconnect driver for Exynos SoCs.
    > diff --git a/drivers/interconnect/exynos/Makefile b/drivers/interconnect/exynos/Makefile
    > new file mode 100644
    > index 0000000..e19d1df
    > --- /dev/null
    > +++ b/drivers/interconnect/exynos/Makefile
    > @@ -0,0 +1,4 @@
    > +# SPDX-License-Identifier: GPL-2.0
    > +exynos-interconnect-objs := exynos.o
    > +
    > +obj-$(CONFIG_INTERCONNECT_EXYNOS) += exynos-interconnect.o
    > diff --git a/drivers/interconnect/exynos/exynos.c b/drivers/interconnect/exynos/exynos.c
    > new file mode 100644
    > index 0000000..8278194
    > --- /dev/null
    > +++ b/drivers/interconnect/exynos/exynos.c
    > @@ -0,0 +1,185 @@
    > +// SPDX-License-Identifier: GPL-2.0-only
    > +/*
    > + * Exynos generic interconnect provider driver
    > + *
    > + * Copyright (c) 2020 Samsung Electronics Co., Ltd.
    > + *
    > + * Authors: Artur Świgoń <a.swigon@samsung.com>
    > + * Sylwester Nawrocki <s.nawrocki@samsung.com>
    > + */
    > +#include <linux/device.h>
    > +#include <linux/interconnect-provider.h>
    > +#include <linux/module.h>
    > +#include <linux/of.h>
    > +#include <linux/platform_device.h>
    > +#include <linux/pm_qos.h>
    > +
    > +#define kbps_to_khz(x) ((x) / 8)
    > +
    > +struct exynos_icc_priv {
    > + struct device *dev;
    > +
    > + /* One interconnect node per provider */
    > + struct icc_provider provider;
    > + struct icc_node *node;
    > +
    > + struct dev_pm_qos_request qos_req;
    > +};
    > +
    > +static struct icc_node *exynos_icc_get_parent(struct device_node *np)
    > +{
    > + struct of_phandle_args args;
    > + int num, ret;
    > +
    > + num = of_count_phandle_with_args(np, "samsung,interconnect-parent",
    > + "#interconnect-cells");
    > + if (num != 1)
    > + return NULL; /* parent nodes are optional */
    > +
    > + ret = of_parse_phandle_with_args(np, "samsung,interconnect-parent",
    > + "#interconnect-cells", 0, &args);
    > + if (ret < 0)
    > + return ERR_PTR(ret);
    > +
    > + of_node_put(args.np);
    > +
    > + return of_icc_get_from_provider(&args);

    I think of_node_put() should happen after of_icc_get_from_provider().

    Best regards,
    Krzysztof

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