[PATCH v15 0/7] power: add power sequence library

[PATCH v15 0/7] power: add power sequence library

[Peter Chen]

This is a follow-up for my last power sequence framework patch set [1].
According to Rob Herring and Ulf Hansson's comments[2]. The kinds of
power sequence instances will be added at postcore_initcall, the match
criteria is compatible string first, if the compatible string is not
matched between dts and library, it will try to use generic power sequence.
	 
The host driver just needs to call of_pwrseq_on/of_pwrseq_off
if only one power sequence instance is needed, for more power sequences
are used, using of_pwrseq_on_list/of_pwrseq_off_list instead (eg, USB hub driver).

In future, if there are special power sequence requirements, the special
power sequence library can be created.

This patch set is tested on i.mx6 sabresx evk using a dts change, I use
two hot-plug devices to simulate this use case, the related binding
change is updated at patch [1/6], The udoo board changes were tested
using my last power sequence patch set.[3]

Except for hard-wired MMC and USB devices, I find the USB ULPI PHY also
need to power on itself before it can be found by ULPI bus.

@Rafael, USB Maintainer has already acked the USB related changes, would you
consider queueing it at v4.13-rc1, sereval guys are waiting for this series.
Thanks.

Changes for v15:
- Change pwrseq list name at USB hub structure (pwrseq_on_list->pwrseq_list). [Patch 4/7]
- Add USB Maintainer's Ack [Patch 4/7]

Changes for v14:
- Rebase for v4.12-rc1
- Delete some USB sysdev patches which has already merged

Changes for v13:
- Add more design descriptions at design doc and fix one build error
  introduced by v12 wrongly [Patch 2/12]
- Add the last three dts patches which were forgotten at last series
- Move the comment for usb_create_shared_hcd to correct place [Patch 3/12]
- Add sysdev for shared hcd too for xhci-plat.c [Patch 6/12]

Rafael, if the first two power sequence patches are ok for you, would you consider
accept these first, the other USB patches can go through USB tree at v4.12-rc1?

Changes for v12:
- Add design doc and more comments at generic power sequence source file [Patch 2/9]
- Introduce four Arnd Bergmann patches and one my ehci related patches, these patches
  are used to get property DT/firmware information at USB code, and these information
  are needed for power sequence operation at USB. With these five patches, my chipidea
  hack patch in previous patch set can be removed. [Patch 3-7/9]
- Add -ENOENT judgement to avoid USB error if no power sequence library is chosen [9/9]

Changes for v11:
- Fix warning: (USB) selects POWER_SEQUENCE which has unmet direct dependencies (OF)
- Delete redundant copyright statement.
- Change pr_warn to pr_debug at wrseq_find_available_instance
- Refine kerneldoc
- %s/ENONET/ENOENT 
- Allocate pwrseq list node before than carry out power sequence on 
- Add mutex_lock/mutex_lock for pwrseq node browse at pwrseq_find_available_instance
- Add pwrseq_suspend/resume for API both single instance and list 
- Add .pwrseq_suspend/resume for pwrseq_generic.c
- Add pwrseq_suspend_list and pwrseq_resume_list for USB hub suspend
  and resume routine

Changes for v10:
- Improve the kernel-doc for power sequence core, including exported APIs and
  main structure. [Patch 2/8]
- Change Kconfig, and let the user choose power sequence. [Patch 2/8]
- Delete EXPORT_SYMBOL and change related APIs as local, these APIs do not
  be intended to export currently. [Patch 2/8]
- Selete POWER_SEQUENCE at USB core's Kconfig. [Patch 4/8]

Changes for v9:
- Add Vaibhav Hiremath's reviewed-by [Patch 4/8]
- Rebase to v4.9-rc1

Changes for v8:
- Allocate one extra pwrseq instance if pwrseq_get has succeed, it can avoid
  preallocate instances problem which the number of instance is decided at
  compile time, thanks for Heiko Stuebner's suggestion [Patch 2/8]
- Delete pwrseq_compatible_sample.c which is the demo purpose to show compatible
  match method. [Patch 2/8]
- Add Maciej S. Szmigiero's tested-by. [Patch 7/8]

Changes for v7:
- Create kinds of power sequence instance at postcore_initcall, and match
  the instance with node using compatible string, the beneit of this is
  the host driver doesn't need to consider which pwrseq instance needs
  to be used, and pwrseq core will match it, however, it eats some memories
  if less power sequence instances are used. [Patch 2/8]
- Add pwrseq_compatible_sample.c to test match pwrseq using device_id. [Patch 2/8]
- Fix the comments Vaibhav Hiremath adds for error path for clock and do not
  use device_node for parameters at pwrseq_on. [Patch 2/8]
- Simplify the caller to use power sequence, follows Alan's commnets [Patch 4/8]
- Tested three pwrseq instances together using both specific compatible string and
  generic libraries.

Changes for v6:
- Add Matthias Kaehlcke's Reviewed-by and Tested-by. (patch [2/6])
- Change chipidea core of_node assignment for coming user. (patch [5/6])
- Applies Joshua Clayton's three dts changes for two boards,
  the USB device's reg has only #address-cells, but without #size-cells.

Changes for v5:
- Delete pwrseq_register/pwrseq_unregister, which is useless currently
- Fix the linker error when the pwrseq user is compiled as module

Changes for v4:
- Create the patch on next-20160722 
- Fix the of_node is not NULL after chipidea driver is unbinded [Patch 5/6]
- Using more friendly wait method for reset gpio [Patch 2/6]
- Support multiple input clocks [Patch 2/6]
- Add Rob Herring's ack for DT changes
- Add Joshua Clayton's Tested-by

Changes for v3:
- Delete "power-sequence" property at binding-doc, and change related code
  at both library and user code.
- Change binding-doc example node name with Rob's comments
- of_get_named_gpio_flags only gets the gpio, but without setting gpio flags,
  add additional code request gpio with proper gpio flags
- Add Philipp Zabel's Ack and MAINTAINER's entry

Changes for v2:
- Delete "pwrseq" prefix and clock-names for properties at dt binding
- Should use structure not but its pointer for kzalloc
- Since chipidea core has no of_node, let core's of_node equals glue
  layer's at core's probe

[1] http://www.spinics.net/lists/linux-usb/msg142755.html
[2] http://www.spinics.net/lists/linux-usb/msg143106.html
[3] http://www.spinics.net/lists/linux-usb/msg142815.html
[4] http://www.spinics.net/lists/linux-usb/msg152375.html

Joshua Clayton (2):
  ARM: dts: imx6qdl: Enable usb node children with <reg>
  ARM: dts: imx6q-evi: Fix onboard hub reset line

Peter Chen (5):
  binding-doc: power: pwrseq-generic: add binding doc for generic power
    sequence library
  power: add power sequence library
  binding-doc: usb: usb-device: add optional properties for power
    sequence
  usb: core: add power sequence handling for USB devices
  ARM: dts: imx6qdl-udoo.dtsi: fix onboard USB HUB property

 .../bindings/power/pwrseq/pwrseq-generic.txt       |  48 +++
 .../devicetree/bindings/usb/usb-device.txt         |  10 +-
 Documentation/power/power-sequence/design.rst      |  54 ++++
 MAINTAINERS                                        |   9 +
 arch/arm/boot/dts/imx6q-evi.dts                    |  25 +-
 arch/arm/boot/dts/imx6qdl-udoo.dtsi                |  26 +-
 arch/arm/boot/dts/imx6qdl.dtsi                     |   6 +
 drivers/power/Kconfig                              |   1 +
 drivers/power/Makefile                             |   1 +
 drivers/power/pwrseq/Kconfig                       |  20 ++
 drivers/power/pwrseq/Makefile                      |   2 +
 drivers/power/pwrseq/core.c                        | 335 +++++++++++++++++++++
 drivers/power/pwrseq/pwrseq_generic.c              | 234 ++++++++++++++
 drivers/usb/Kconfig                                |   1 +
 drivers/usb/core/hub.c                             |  49 ++-
 drivers/usb/core/hub.h                             |   1 +
 include/linux/power/pwrseq.h                       |  81 +++++
 17 files changed, 866 insertions(+), 37 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt
 create mode 100644 Documentation/power/power-sequence/design.rst
 create mode 100644 drivers/power/pwrseq/Kconfig
 create mode 100644 drivers/power/pwrseq/Makefile
 create mode 100644 drivers/power/pwrseq/core.c
 create mode 100644 drivers/power/pwrseq/pwrseq_generic.c
 create mode 100644 include/linux/power/pwrseq.h

-- 
2.7.4

[PATCH v15 1/7] binding-doc: power: pwrseq-generic: add binding doc for generic power sequence library

[Peter Chen]

Add binding doc for generic power sequence library.

Signed-off-by: Peter Chen <peter.chen@nxp.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
---
 .../bindings/power/pwrseq/pwrseq-generic.txt       | 48 ++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt

diff --git a/Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt b/Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt
new file mode 100644
index 0000000..ebf0d47
--- /dev/null
+++ b/Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt
@@ -0,0 +1,48 @@
+The generic power sequence library
+
+Some hard-wired devices (eg USB/MMC) need to do power sequence before
+the device can be enumerated on the bus, the typical power sequence
+like: enable USB PHY clock, toggle reset pin, etc. But current
+Linux device driver lacks of such code to do it, it may cause some
+hard-wired devices works abnormal or can't be recognized by
+controller at all. The power sequence will be done before this device
+can be found at the bus.
+
+The power sequence properties is under the device node.
+
+Optional properties:
+- clocks: the input clocks for device.
+- reset-gpios: Should specify the GPIO for reset.
+- reset-duration-us: the duration in microsecond for assert reset signal.
+
+Below is the example of USB power sequence properties on USB device
+nodes which have two level USB hubs.
+
+&usbotg1 {
+	vbus-supply = <&reg_usb_otg1_vbus>;
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_usb_otg1_id>;
+	status = "okay";
+
+	#address-cells = <1>;
+	#size-cells = <0>;
+	genesys: hub@1 {
+		compatible = "usb5e3,608";
+		reg = <1>;
+
+		clocks = <&clks IMX6SX_CLK_CKO>;
+		reset-gpios = <&gpio4 5 GPIO_ACTIVE_LOW>; /* hub reset pin */
+		reset-duration-us = <10>;
+
+		#address-cells = <1>;
+		#size-cells = <0>;
+		asix: ethernet@1 {
+			compatible = "usbb95,1708";
+			reg = <1>;
+
+			clocks = <&clks IMX6SX_CLK_IPG>;
+			reset-gpios = <&gpio4 6 GPIO_ACTIVE_LOW>; /* ethernet_rst */
+			reset-duration-us = <15>;
+		};
+	};
+};
-- 
2.7.4

[PATCH v15 2/7] power: add power sequence library

[Peter Chen]

We have an well-known problem that the device needs to do some power
sequence before it can be recognized by related host, the typical
example like hard-wired mmc devices and usb devices.

This power sequence is hard to be described at device tree and handled by
related host driver, so we have created a common power sequence
library to cover this requirement. The core code has supplied
some common helpers for host driver, and individual power sequence
libraries handle kinds of power sequence for devices. The pwrseq
librares always need to allocate extra instance for compatible
string match.

pwrseq_generic is intended for general purpose of power sequence, which
handles gpios and clocks currently, and can cover other controls in
future. The host driver just needs to call of_pwrseq_on/of_pwrseq_off
if only one power sequence is needed, else call of_pwrseq_on_list
/of_pwrseq_off_list instead (eg, USB hub driver).

For new power sequence library, it can add its compatible string
to pwrseq_of_match_table, then the pwrseq core will match it with
DT's, and choose this library at runtime.

Signed-off-by: Peter Chen <peter.chen@nxp.com>
Tested-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Tested-by Joshua Clayton <stillcompiling@gmail.com>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Tested-by: Matthias Kaehlcke <mka@chromium.org>
---
 Documentation/power/power-sequence/design.rst |  54 +++++
 MAINTAINERS                                   |   9 +
 drivers/power/Kconfig                         |   1 +
 drivers/power/Makefile                        |   1 +
 drivers/power/pwrseq/Kconfig                  |  20 ++
 drivers/power/pwrseq/Makefile                 |   2 +
 drivers/power/pwrseq/core.c                   | 335 ++++++++++++++++++++++++++
 drivers/power/pwrseq/pwrseq_generic.c         | 234 ++++++++++++++++++
 include/linux/power/pwrseq.h                  |  81 +++++++
 9 files changed, 737 insertions(+)
 create mode 100644 Documentation/power/power-sequence/design.rst
 create mode 100644 drivers/power/pwrseq/Kconfig
 create mode 100644 drivers/power/pwrseq/Makefile
 create mode 100644 drivers/power/pwrseq/core.c
 create mode 100644 drivers/power/pwrseq/pwrseq_generic.c
 create mode 100644 include/linux/power/pwrseq.h

diff --git a/Documentation/power/power-sequence/design.rst b/Documentation/power/power-sequence/design.rst
new file mode 100644
index 0000000..554608e
--- /dev/null
+++ b/Documentation/power/power-sequence/design.rst
@@ -0,0 +1,54 @@
+====================================
+Power Sequence Library
+====================================
+
+:Date: Feb, 2017
+:Author: Peter Chen <peter.chen@nxp.com>
+
+
+Introduction
+============
+
+We have an well-known problem that the device needs to do a power
+sequence before it can be recognized by related host, the typical
+examples are hard-wired mmc devices and usb devices. The host controller
+can't know what kinds of this device is in its bus if the power
+sequence has not done, since the related devices driver's probe calling
+is determined by runtime according to eunumeration results. Besides,
+the devices may have custom power sequence, so the power sequence library
+which is independent with the devices is needed.
+
+Design
+============
+
+The power sequence library includes the core file and customer power
+sequence library. The core file exports interfaces are called by
+host controller driver for power sequence and customer power sequence
+library files to register its power sequence instance to global
+power sequence list. The custom power sequence library creates power
+sequence instance and implement custom power sequence.
+
+Since the power sequence describes hardware design, the description is
+located at board description file, eg, device tree dts file. And
+a specific power sequence belongs to device, so its description
+is under the device node, please refer to:
+Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt
+
+Custom power sequence library allocates one power sequence instance at
+bootup periods using postcore_initcall, this static allocated instance is
+used to compare with device-tree (DT) node to see if this library can be
+used for the node or not. When the result is matched, the core API will
+try to get resourses (->get, implemented at each library) for power
+sequence, if all resources are got, it will try to allocate another
+instance for next possible request from host driver.
+
+Then, the host controller driver can carry out power sequence on for this
+DT node, the library will do corresponding operations, like open clocks,
+toggle gpio, etc. The power sequence off routine will close and free the
+resources, and is called when the parent is removed. And the power
+sequence suspend and resume routine can be called at host driver's
+suspend and resume routine if needed.
+
+The exported interfaces
+.. kernel-doc:: drivers/power/pwrseq/core.c
+   :export:
diff --git a/MAINTAINERS b/MAINTAINERS
index f7d568b..93b07aa 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10188,6 +10188,15 @@ F:	include/linux/pm_*
 F:	include/linux/powercap.h
 F:	drivers/powercap/
 
+POWER SEQUENCE LIBRARY
+M:	Peter Chen <Peter.Chen@nxp.com>
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/peter.chen/usb.git
+L:	linux-pm@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/power/pwrseq/
+F:	drivers/power/pwrseq/
+F:	include/linux/power/pwrseq.h
+
 POWER SUPPLY CLASS/SUBSYSTEM and DRIVERS
 M:	Sebastian Reichel <sre@kernel.org>
 L:	linux-pm@vger.kernel.org
diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
index 63454b5..c1bb046 100644
--- a/drivers/power/Kconfig
+++ b/drivers/power/Kconfig
@@ -1,3 +1,4 @@
 source "drivers/power/avs/Kconfig"
 source "drivers/power/reset/Kconfig"
 source "drivers/power/supply/Kconfig"
+source "drivers/power/pwrseq/Kconfig"
diff --git a/drivers/power/Makefile b/drivers/power/Makefile
index ff35c71..7db8035 100644
--- a/drivers/power/Makefile
+++ b/drivers/power/Makefile
@@ -1,3 +1,4 @@
 obj-$(CONFIG_POWER_AVS)		+= avs/
 obj-$(CONFIG_POWER_RESET)	+= reset/
 obj-$(CONFIG_POWER_SUPPLY)	+= supply/
+obj-$(CONFIG_POWER_SEQUENCE)	+= pwrseq/
diff --git a/drivers/power/pwrseq/Kconfig b/drivers/power/pwrseq/Kconfig
new file mode 100644
index 0000000..c6b3569
--- /dev/null
+++ b/drivers/power/pwrseq/Kconfig
@@ -0,0 +1,20 @@
+#
+# Power Sequence library
+#
+
+menuconfig POWER_SEQUENCE
+	bool "Power sequence control"
+	help
+	   It is used for drivers which needs to do power sequence
+	   (eg, turn on clock, toggle reset gpio) before the related
+	   devices can be found by hardware, eg, USB bus.
+
+if POWER_SEQUENCE
+
+config PWRSEQ_GENERIC
+	bool "Generic power sequence control"
+	depends on OF
+	help
+	   This is the generic power sequence control library, and is
+	   supposed to support common power sequence usage.
+endif
diff --git a/drivers/power/pwrseq/Makefile b/drivers/power/pwrseq/Makefile
new file mode 100644
index 0000000..ad82389
--- /dev/null
+++ b/drivers/power/pwrseq/Makefile
@@ -0,0 +1,2 @@
+obj-$(CONFIG_POWER_SEQUENCE) += core.o
+obj-$(CONFIG_PWRSEQ_GENERIC) += pwrseq_generic.o
diff --git a/drivers/power/pwrseq/core.c b/drivers/power/pwrseq/core.c
new file mode 100644
index 0000000..3d19e62
--- /dev/null
+++ b/drivers/power/pwrseq/core.c
@@ -0,0 +1,335 @@
+/*
+ * core.c	power sequence core file
+ *
+ * Copyright (C) 2016 Freescale Semiconductor, Inc.
+ * Author: Peter Chen <peter.chen@nxp.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2  of
+ * the License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.
+ */
+
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/power/pwrseq.h>
+
+static DEFINE_MUTEX(pwrseq_list_mutex);
+static LIST_HEAD(pwrseq_list);
+
+static int pwrseq_get(struct device_node *np, struct pwrseq *p)
+{
+	if (p && p->get)
+		return p->get(np, p);
+
+	return -ENOTSUPP;
+}
+
+static int pwrseq_on(struct pwrseq *p)
+{
+	if (p && p->on)
+		return p->on(p);
+
+	return -ENOTSUPP;
+}
+
+static void pwrseq_off(struct pwrseq *p)
+{
+	if (p && p->off)
+		p->off(p);
+}
+
+static void pwrseq_put(struct pwrseq *p)
+{
+	if (p && p->put)
+		p->put(p);
+}
+
+/**
+ * pwrseq_register - Add pwrseq instance to global pwrseq list
+ *
+ * @pwrseq: the pwrseq instance
+ */
+void pwrseq_register(struct pwrseq *pwrseq)
+{
+	mutex_lock(&pwrseq_list_mutex);
+	list_add(&pwrseq->node, &pwrseq_list);
+	mutex_unlock(&pwrseq_list_mutex);
+}
+EXPORT_SYMBOL_GPL(pwrseq_register);
+
+/**
+ * pwrseq_unregister - Remove pwrseq instance from global pwrseq list
+ *
+ * @pwrseq: the pwrseq instance
+ */
+void pwrseq_unregister(struct pwrseq *pwrseq)
+{
+	mutex_lock(&pwrseq_list_mutex);
+	list_del(&pwrseq->node);
+	mutex_unlock(&pwrseq_list_mutex);
+}
+EXPORT_SYMBOL_GPL(pwrseq_unregister);
+
+static struct pwrseq *pwrseq_find_available_instance(struct device_node *np)
+{
+	struct pwrseq *pwrseq;
+
+	mutex_lock(&pwrseq_list_mutex);
+	list_for_each_entry(pwrseq, &pwrseq_list, node) {
+		if (pwrseq->used)
+			continue;
+
+		/* compare compatible string for pwrseq node */
+		if (of_match_node(pwrseq->pwrseq_of_match_table, np)) {
+			pwrseq->used = true;
+			mutex_unlock(&pwrseq_list_mutex);
+			return pwrseq;
+		}
+
+		/* return generic pwrseq instance */
+		if (!strcmp(pwrseq->pwrseq_of_match_table->compatible,
+				"generic")) {
+			pr_debug("using generic pwrseq instance for %s\n",
+				np->full_name);
+			pwrseq->used = true;
+			mutex_unlock(&pwrseq_list_mutex);
+			return pwrseq;
+		}
+	}
+	mutex_unlock(&pwrseq_list_mutex);
+	pr_debug("Can't find any pwrseq instances for %s\n", np->full_name);
+
+	return NULL;
+}
+
+/**
+ * of_pwrseq_on - Carry out power sequence on for device node
+ *
+ * @np: the device node would like to power on
+ *
+ * Carry out a single device power on.  If multiple devices
+ * need to be handled, use of_pwrseq_on_list() instead.
+ *
+ * Return a pointer to the power sequence instance on success,
+ * or an error code otherwise.
+ */
+struct pwrseq *of_pwrseq_on(struct device_node *np)
+{
+	struct pwrseq *pwrseq;
+	int ret;
+
+	pwrseq = pwrseq_find_available_instance(np);
+	if (!pwrseq)
+		return ERR_PTR(-ENOENT);
+
+	ret = pwrseq_get(np, pwrseq);
+	if (ret) {
+		/* Mark current pwrseq as unused */
+		pwrseq->used = false;
+		return ERR_PTR(ret);
+	}
+
+	ret = pwrseq_on(pwrseq);
+	if (ret)
+		goto pwr_put;
+
+	return pwrseq;
+
+pwr_put:
+	pwrseq_put(pwrseq);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(of_pwrseq_on);
+
+/**
+ * of_pwrseq_off - Carry out power sequence off for this pwrseq instance
+ *
+ * @pwrseq: the pwrseq instance which related device would like to be off
+ *
+ * This API is used to power off single device, it is the opposite
+ * operation for of_pwrseq_on.
+ */
+void of_pwrseq_off(struct pwrseq *pwrseq)
+{
+	pwrseq_off(pwrseq);
+	pwrseq_put(pwrseq);
+}
+EXPORT_SYMBOL_GPL(of_pwrseq_off);
+
+/**
+ * of_pwrseq_on_list - Carry out power sequence on for list
+ *
+ * @np: the device node would like to power on
+ * @head: the list head for pwrseq list on this bus
+ *
+ * This API is used to power on multiple devices at single bus.
+ * If there are several devices on bus (eg, USB bus), uses this
+ * this API. Otherwise, use of_pwrseq_on instead. After the device
+ * is powered on successfully, it will be added to pwrseq list for
+ * this bus. The caller needs to use mutex_lock for concurrent.
+ *
+ * Return 0 on success, or an error value otherwise.
+ */
+int of_pwrseq_on_list(struct device_node *np, struct list_head *head)
+{
+	struct pwrseq *pwrseq;
+	struct pwrseq_list_per_dev *pwrseq_list_node;
+
+	pwrseq_list_node = kzalloc(sizeof(*pwrseq_list_node), GFP_KERNEL);
+	if (!pwrseq_list_node)
+		return -ENOMEM;
+
+	pwrseq = of_pwrseq_on(np);
+	if (IS_ERR(pwrseq)) {
+		kfree(pwrseq_list_node);
+		return PTR_ERR(pwrseq);
+	}
+
+	pwrseq_list_node->pwrseq = pwrseq;
+	list_add(&pwrseq_list_node->list, head);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_pwrseq_on_list);
+
+/**
+ * of_pwrseq_off_list - Carry out power sequence off for the list
+ *
+ * @head: the list head for pwrseq instance list on this bus
+ *
+ * This API is used to power off all devices on this bus, it is
+ * the opposite operation for of_pwrseq_on_list.
+ * The caller needs to use mutex_lock for concurrent.
+ */
+void of_pwrseq_off_list(struct list_head *head)
+{
+	struct pwrseq *pwrseq;
+	struct pwrseq_list_per_dev *pwrseq_list_node, *tmp_node;
+
+	list_for_each_entry_safe(pwrseq_list_node, tmp_node, head, list) {
+		pwrseq = pwrseq_list_node->pwrseq;
+		of_pwrseq_off(pwrseq);
+		list_del(&pwrseq_list_node->list);
+		kfree(pwrseq_list_node);
+	}
+}
+EXPORT_SYMBOL_GPL(of_pwrseq_off_list);
+
+/**
+ * pwrseq_suspend - Carry out power sequence suspend for this pwrseq instance
+ *
+ * @pwrseq: the pwrseq instance
+ *
+ * This API is used to do suspend operation on pwrseq instance.
+ *
+ * Return 0 on success, or an error value otherwise.
+ */
+int pwrseq_suspend(struct pwrseq *p)
+{
+	int ret = 0;
+
+	if (p && p->suspend)
+		ret = p->suspend(p);
+	else
+		return ret;
+
+	if (!ret)
+		p->suspended = true;
+	else
+		pr_err("%s failed\n", __func__);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pwrseq_suspend);
+
+/**
+ * pwrseq_resume - Carry out power sequence resume for this pwrseq instance
+ *
+ * @pwrseq: the pwrseq instance
+ *
+ * This API is used to do resume operation on pwrseq instance.
+ *
+ * Return 0 on success, or an error value otherwise.
+ */
+int pwrseq_resume(struct pwrseq *p)
+{
+	int ret = 0;
+
+	if (p && p->resume)
+		ret = p->resume(p);
+	else
+		return ret;
+
+	if (!ret)
+		p->suspended = false;
+	else
+		pr_err("%s failed\n", __func__);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pwrseq_resume);
+
+/**
+ * pwrseq_suspend_list - Carry out power sequence suspend for list
+ *
+ * @head: the list head for pwrseq instance list on this bus
+ *
+ * This API is used to do suspend on all power sequence instances on this bus.
+ * The caller needs to use mutex_lock for concurrent.
+ */
+int pwrseq_suspend_list(struct list_head *head)
+{
+	struct pwrseq *pwrseq;
+	struct pwrseq_list_per_dev *pwrseq_list_node;
+	int ret = 0;
+
+	list_for_each_entry(pwrseq_list_node, head, list) {
+		ret = pwrseq_suspend(pwrseq_list_node->pwrseq);
+		if (ret)
+			break;
+	}
+
+	if (ret) {
+		list_for_each_entry(pwrseq_list_node, head, list) {
+			pwrseq = pwrseq_list_node->pwrseq;
+			if (pwrseq->suspended)
+				pwrseq_resume(pwrseq);
+		}
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pwrseq_suspend_list);
+
+/**
+ * pwrseq_resume_list - Carry out power sequence resume for the list
+ *
+ * @head: the list head for pwrseq instance list on this bus
+ *
+ * This API is used to do resume on all power sequence instances on this bus.
+ * The caller needs to use mutex_lock for concurrent.
+ */
+int pwrseq_resume_list(struct list_head *head)
+{
+	struct pwrseq_list_per_dev *pwrseq_list_node;
+	int ret = 0;
+
+	list_for_each_entry(pwrseq_list_node, head, list) {
+		ret = pwrseq_resume(pwrseq_list_node->pwrseq);
+		if (ret)
+			break;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pwrseq_resume_list);
diff --git a/drivers/power/pwrseq/pwrseq_generic.c b/drivers/power/pwrseq/pwrseq_generic.c
new file mode 100644
index 0000000..4e7c090
--- /dev/null
+++ b/drivers/power/pwrseq/pwrseq_generic.c
@@ -0,0 +1,234 @@
+/*
+ * pwrseq_generic.c	Generic power sequence handling
+ *
+ * Copyright (C) 2016 Freescale Semiconductor, Inc.
+ * Author: Peter Chen <peter.chen@nxp.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2  of
+ * the License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/slab.h>
+
+#include <linux/power/pwrseq.h>
+
+struct pwrseq_generic {
+	struct pwrseq pwrseq;
+	struct gpio_desc *gpiod_reset;
+	struct clk *clks[PWRSEQ_MAX_CLKS];
+	u32 duration_us;
+	bool suspended;
+};
+
+#define to_generic_pwrseq(p) container_of(p, struct pwrseq_generic, pwrseq)
+
+static int pwrseq_generic_alloc_instance(void);
+static const struct of_device_id generic_id_table[] = {
+	{ .compatible = "generic",},
+	{ /* sentinel */ }
+};
+
+static int pwrseq_generic_suspend(struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	int clk;
+
+	for (clk = PWRSEQ_MAX_CLKS - 1; clk >= 0; clk--)
+		clk_disable_unprepare(pwrseq_gen->clks[clk]);
+
+	pwrseq_gen->suspended = true;
+	return 0;
+}
+
+static int pwrseq_generic_resume(struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	int clk, ret = 0;
+
+	for (clk = 0; clk < PWRSEQ_MAX_CLKS && pwrseq_gen->clks[clk]; clk++) {
+		ret = clk_prepare_enable(pwrseq_gen->clks[clk]);
+		if (ret) {
+			pr_err("Can't enable clock, ret=%d\n", ret);
+			goto err_disable_clks;
+		}
+	}
+
+	pwrseq_gen->suspended = false;
+	return ret;
+
+err_disable_clks:
+	while (--clk >= 0)
+		clk_disable_unprepare(pwrseq_gen->clks[clk]);
+
+	return ret;
+}
+
+static void pwrseq_generic_put(struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	int clk;
+
+	if (pwrseq_gen->gpiod_reset)
+		gpiod_put(pwrseq_gen->gpiod_reset);
+
+	for (clk = 0; clk < PWRSEQ_MAX_CLKS; clk++)
+		clk_put(pwrseq_gen->clks[clk]);
+
+	pwrseq_unregister(&pwrseq_gen->pwrseq);
+	kfree(pwrseq_gen);
+}
+
+static void pwrseq_generic_off(struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	int clk;
+
+	if (pwrseq_gen->suspended)
+		return;
+
+	for (clk = PWRSEQ_MAX_CLKS - 1; clk >= 0; clk--)
+		clk_disable_unprepare(pwrseq_gen->clks[clk]);
+}
+
+static int pwrseq_generic_on(struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	int clk, ret = 0;
+	struct gpio_desc *gpiod_reset = pwrseq_gen->gpiod_reset;
+
+	for (clk = 0; clk < PWRSEQ_MAX_CLKS && pwrseq_gen->clks[clk]; clk++) {
+		ret = clk_prepare_enable(pwrseq_gen->clks[clk]);
+		if (ret) {
+			pr_err("Can't enable clock, ret=%d\n", ret);
+			goto err_disable_clks;
+		}
+	}
+
+	if (gpiod_reset) {
+		u32 duration_us = pwrseq_gen->duration_us;
+
+		if (duration_us <= 10)
+			udelay(10);
+		else
+			usleep_range(duration_us, duration_us + 100);
+		gpiod_set_value(gpiod_reset, 0);
+	}
+
+	return ret;
+
+err_disable_clks:
+	while (--clk >= 0)
+		clk_disable_unprepare(pwrseq_gen->clks[clk]);
+
+	return ret;
+}
+
+static int pwrseq_generic_get(struct device_node *np, struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	enum of_gpio_flags flags;
+	int reset_gpio, clk, ret = 0;
+
+	for (clk = 0; clk < PWRSEQ_MAX_CLKS; clk++) {
+		pwrseq_gen->clks[clk] = of_clk_get(np, clk);
+		if (IS_ERR(pwrseq_gen->clks[clk])) {
+			ret = PTR_ERR(pwrseq_gen->clks[clk]);
+			if (ret != -ENOENT)
+				goto err_put_clks;
+			pwrseq_gen->clks[clk] = NULL;
+			break;
+		}
+	}
+
+	reset_gpio = of_get_named_gpio_flags(np, "reset-gpios", 0, &flags);
+	if (gpio_is_valid(reset_gpio)) {
+		unsigned long gpio_flags;
+
+		if (flags & OF_GPIO_ACTIVE_LOW)
+			gpio_flags = GPIOF_ACTIVE_LOW | GPIOF_OUT_INIT_LOW;
+		else
+			gpio_flags = GPIOF_OUT_INIT_HIGH;
+
+		ret = gpio_request_one(reset_gpio, gpio_flags,
+				"pwrseq-reset-gpios");
+		if (ret)
+			goto err_put_clks;
+
+		pwrseq_gen->gpiod_reset = gpio_to_desc(reset_gpio);
+		of_property_read_u32(np, "reset-duration-us",
+				&pwrseq_gen->duration_us);
+	} else if (reset_gpio == -ENOENT) {
+		; /* no such gpio */
+	} else {
+		ret = reset_gpio;
+		pr_err("Failed to get reset gpio on %s, err = %d\n",
+				np->full_name, reset_gpio);
+		goto err_put_clks;
+	}
+
+	/* allocate new one for later pwrseq instance request */
+	ret = pwrseq_generic_alloc_instance();
+	if (ret)
+		goto err_put_gpio;
+
+	return 0;
+
+err_put_gpio:
+	if (pwrseq_gen->gpiod_reset)
+		gpiod_put(pwrseq_gen->gpiod_reset);
+err_put_clks:
+	while (--clk >= 0)
+		clk_put(pwrseq_gen->clks[clk]);
+	return ret;
+}
+
+/**
+ * pwrseq_generic_alloc_instance - power sequence instance allocation
+ *
+ * This function is used to allocate one generic power sequence instance,
+ * it is called when the system boots up and after one power sequence
+ * instance is got successfully.
+ *
+ * Return zero on success or an error code otherwise.
+ */
+static int pwrseq_generic_alloc_instance(void)
+{
+	struct pwrseq_generic *pwrseq_gen;
+
+	pwrseq_gen = kzalloc(sizeof(*pwrseq_gen), GFP_KERNEL);
+	if (!pwrseq_gen)
+		return -ENOMEM;
+
+	pwrseq_gen->pwrseq.pwrseq_of_match_table = generic_id_table;
+	pwrseq_gen->pwrseq.get = pwrseq_generic_get;
+	pwrseq_gen->pwrseq.on = pwrseq_generic_on;
+	pwrseq_gen->pwrseq.off = pwrseq_generic_off;
+	pwrseq_gen->pwrseq.put = pwrseq_generic_put;
+	pwrseq_gen->pwrseq.suspend = pwrseq_generic_suspend;
+	pwrseq_gen->pwrseq.resume = pwrseq_generic_resume;
+
+	pwrseq_register(&pwrseq_gen->pwrseq);
+	return 0;
+}
+
+/* Allocate one pwrseq instance during boots up */
+static int __init pwrseq_generic_register(void)
+{
+	return pwrseq_generic_alloc_instance();
+}
+postcore_initcall(pwrseq_generic_register)
diff --git a/include/linux/power/pwrseq.h b/include/linux/power/pwrseq.h
new file mode 100644
index 0000000..cbc344c
--- /dev/null
+++ b/include/linux/power/pwrseq.h
@@ -0,0 +1,81 @@
+#ifndef __LINUX_PWRSEQ_H
+#define __LINUX_PWRSEQ_H
+
+#include <linux/of.h>
+
+#define PWRSEQ_MAX_CLKS		3
+
+/**
+ * struct pwrseq - the power sequence structure
+ * @pwrseq_of_match_table: the OF device id table this pwrseq library supports
+ * @node: the list pointer to be added to pwrseq list
+ * @get: the API is used to get pwrseq instance from the device node
+ * @on: do power on for this pwrseq instance
+ * @off: do power off for this pwrseq instance
+ * @put: release the resources on this pwrseq instance
+ * @suspend: do suspend operation on this pwrseq instance
+ * @resume: do resume operation on this pwrseq instance
+ * @used: this pwrseq instance is used by device
+ */
+struct pwrseq {
+	const struct of_device_id *pwrseq_of_match_table;
+	struct list_head node;
+	int (*get)(struct device_node *np, struct pwrseq *p);
+	int (*on)(struct pwrseq *p);
+	void (*off)(struct pwrseq *p);
+	void (*put)(struct pwrseq *p);
+	int (*suspend)(struct pwrseq *p);
+	int (*resume)(struct pwrseq *p);
+	bool used;
+	bool suspended;
+};
+
+/* used for power sequence instance list in one driver */
+struct pwrseq_list_per_dev {
+	struct pwrseq *pwrseq;
+	struct list_head list;
+};
+
+#if IS_ENABLED(CONFIG_POWER_SEQUENCE)
+void pwrseq_register(struct pwrseq *pwrseq);
+void pwrseq_unregister(struct pwrseq *pwrseq);
+struct pwrseq *of_pwrseq_on(struct device_node *np);
+void of_pwrseq_off(struct pwrseq *pwrseq);
+int of_pwrseq_on_list(struct device_node *np, struct list_head *head);
+void of_pwrseq_off_list(struct list_head *head);
+int pwrseq_suspend(struct pwrseq *p);
+int pwrseq_resume(struct pwrseq *p);
+int pwrseq_suspend_list(struct list_head *head);
+int pwrseq_resume_list(struct list_head *head);
+#else
+static inline void pwrseq_register(struct pwrseq *pwrseq) {}
+static inline void pwrseq_unregister(struct pwrseq *pwrseq) {}
+static inline struct pwrseq *of_pwrseq_on(struct device_node *np)
+{
+	return NULL;
+}
+static void of_pwrseq_off(struct pwrseq *pwrseq) {}
+static int of_pwrseq_on_list(struct device_node *np, struct list_head *head)
+{
+	return 0;
+}
+static void of_pwrseq_off_list(struct list_head *head) {}
+static int pwrseq_suspend(struct pwrseq *p)
+{
+	return 0;
+}
+static int pwrseq_resume(struct pwrseq *p)
+{
+	return 0;
+}
+static int pwrseq_suspend_list(struct list_head *head)
+{
+	return 0;
+}
+static int pwrseq_resume_list(struct list_head *head)
+{
+	return 0;
+}
+#endif /* CONFIG_POWER_SEQUENCE */
+
+#endif  /* __LINUX_PWRSEQ_H */
-- 
2.7.4

[PATCH v15 3/7] binding-doc: usb: usb-device: add optional properties for power sequence

[Peter Chen]

Add optional properties for power sequence.

Signed-off-by: Peter Chen <peter.chen@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
---
 Documentation/devicetree/bindings/usb/usb-device.txt | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/usb/usb-device.txt b/Documentation/devicetree/bindings/usb/usb-device.txt
index 1c35e7b..3661dd2 100644
--- a/Documentation/devicetree/bindings/usb/usb-device.txt
+++ b/Documentation/devicetree/bindings/usb/usb-device.txt
@@ -13,6 +13,10 @@ Required properties:
 - reg: the port number which this device is connecting to, the range
   is 1-31.
 
+Optional properties:
+power sequence properties, see
+Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt for detail
+
 Example:
 
 &usb1 {
@@ -21,8 +25,12 @@ Example:
 	#address-cells = <1>;
 	#size-cells = <0>;
 
-	hub: genesys@1 {
+	genesys: hub@1 {
 		compatible = "usb5e3,608";
 		reg = <1>;
+
+		clocks = <&clks IMX6SX_CLK_CKO>;
+		reset-gpios = <&gpio4 5 GPIO_ACTIVE_LOW>; /* hub reset pin */
+		reset-duration-us = <10>;
 	};
 }
-- 
2.7.4

[PATCH v15 4/7] usb: core: add power sequence handling for USB devices

[Peter Chen]

Some hard-wired USB devices need to do power sequence to let the
device work normally, the typical power sequence like: enable USB
PHY clock, toggle reset pin, etc. But current Linux USB driver
lacks of such code to do it, it may cause some hard-wired USB devices
works abnormal or can't be recognized by controller at all.

In this patch, it calls power sequence library APIs to finish
the power sequence events. It will do power on sequence at hub's
probe for all devices under this hub (includes root hub).
At hub_disconnect, it will do power off sequence which is at powered
on list.

Signed-off-by: Peter Chen <peter.chen@nxp.com>
Tested-by Joshua Clayton <stillcompiling@gmail.com>
Tested-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Reviewed-by: Vaibhav Hiremath <hvaibhav.linux@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
---
 drivers/usb/Kconfig    |  1 +
 drivers/usb/core/hub.c | 49 +++++++++++++++++++++++++++++++++++++++++++++----
 drivers/usb/core/hub.h |  1 +
 3 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/Kconfig b/drivers/usb/Kconfig
index 939a63b..b6f626e 100644
--- a/drivers/usb/Kconfig
+++ b/drivers/usb/Kconfig
@@ -39,6 +39,7 @@ config USB
 	tristate "Support for Host-side USB"
 	depends on USB_ARCH_HAS_HCD
 	select USB_COMMON
+	select POWER_SEQUENCE
 	select NLS  # for UTF-8 strings
 	---help---
 	  Universal Serial Bus (USB) is a specification for a serial bus
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 9dca59e..0439d4f 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -28,6 +28,7 @@
 #include <linux/mutex.h>
 #include <linux/random.h>
 #include <linux/pm_qos.h>
+#include <linux/power/pwrseq.h>
 
 #include <linux/uaccess.h>
 #include <asm/byteorder.h>
@@ -1619,6 +1620,7 @@ static void hub_disconnect(struct usb_interface *intf)
 	hub->error = 0;
 	hub_quiesce(hub, HUB_DISCONNECT);
 
+	of_pwrseq_off_list(&hub->pwrseq_list);
 	mutex_lock(&usb_port_peer_mutex);
 
 	/* Avoid races with recursively_mark_NOTATTACHED() */
@@ -1646,12 +1648,42 @@ static void hub_disconnect(struct usb_interface *intf)
 	kref_put(&hub->kref, hub_release);
 }
 
+#ifdef CONFIG_OF
+static int hub_of_pwrseq_on(struct usb_hub *hub)
+{
+	struct device *parent;
+	struct usb_device *hdev = hub->hdev;
+	struct device_node *np;
+	int ret;
+
+	if (hdev->parent)
+		parent = &hdev->dev;
+	else
+		parent = bus_to_hcd(hdev->bus)->self.sysdev;
+
+	for_each_child_of_node(parent->of_node, np) {
+		ret = of_pwrseq_on_list(np, &hub->pwrseq_list);
+		/* Maybe no power sequence library is chosen */
+		if (ret && ret != -ENOENT)
+			return ret;
+	}
+
+	return 0;
+}
+#else
+static int hub_of_pwrseq_on(struct usb_hub *hub)
+{
+	return 0;
+}
+#endif
+
 static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
 {
 	struct usb_host_interface *desc;
 	struct usb_endpoint_descriptor *endpoint;
 	struct usb_device *hdev;
 	struct usb_hub *hub;
+	int ret = -ENODEV;
 
 	desc = intf->cur_altsetting;
 	hdev = interface_to_usbdev(intf);
@@ -1756,6 +1788,7 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
 	INIT_DELAYED_WORK(&hub->leds, led_work);
 	INIT_DELAYED_WORK(&hub->init_work, NULL);
 	INIT_WORK(&hub->events, hub_event);
+	INIT_LIST_HEAD(&hub->pwrseq_list);
 	usb_get_intf(intf);
 	usb_get_dev(hdev);
 
@@ -1769,11 +1802,14 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
 	if (id->driver_info & HUB_QUIRK_CHECK_PORT_AUTOSUSPEND)
 		hub->quirk_check_port_auto_suspend = 1;
 
-	if (hub_configure(hub, endpoint) >= 0)
-		return 0;
+	if (hub_configure(hub, endpoint) >= 0) {
+		ret = hub_of_pwrseq_on(hub);
+		if (!ret)
+			return 0;
+	}
 
 	hub_disconnect(intf);
-	return -ENODEV;
+	return ret;
 }
 
 static int
@@ -3593,14 +3629,19 @@ static int hub_suspend(struct usb_interface *intf, pm_message_t msg)
 
 	/* stop hub_wq and related activity */
 	hub_quiesce(hub, HUB_SUSPEND);
-	return 0;
+	return pwrseq_suspend_list(&hub->pwrseq_list);
 }
 
 static int hub_resume(struct usb_interface *intf)
 {
 	struct usb_hub *hub = usb_get_intfdata(intf);
+	int ret;
 
 	dev_dbg(&intf->dev, "%s\n", __func__);
+	ret = pwrseq_resume_list(&hub->pwrseq_list);
+	if (ret)
+		return ret;
+
 	hub_activate(hub, HUB_RESUME);
 	return 0;
 }
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 34c1a7e..27f56a6 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -78,6 +78,7 @@ struct usb_hub {
 	struct delayed_work	init_work;
 	struct work_struct      events;
 	struct usb_port		**ports;
+	struct list_head	pwrseq_list; /* powered pwrseq node list */
 };
 
 /**
-- 
2.7.4

[PATCH v15 5/7] ARM: dts: imx6qdl: Enable usb node children with <reg>

[Peter Chen]

From: Joshua Clayton <stillcompiling@gmail.com>

Give usb nodes #address and #size attributes, so that a child node
representing a permanently connected device such as an onboard hub may
be addressed with a <reg> attribute

Signed-off-by: Joshua Clayton <stillcompiling@gmail.com>
Signed-off-by: Peter Chen <peter.chen@nxp.com>
---
 arch/arm/boot/dts/imx6qdl.dtsi | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm/boot/dts/imx6qdl.dtsi b/arch/arm/boot/dts/imx6qdl.dtsi
index e426faa..8c064cb 100644
--- a/arch/arm/boot/dts/imx6qdl.dtsi
+++ b/arch/arm/boot/dts/imx6qdl.dtsi
@@ -945,6 +945,8 @@
 
 			usbh1: usb@02184200 {
 				compatible = "fsl,imx6q-usb", "fsl,imx27-usb";
+				#address-cells = <1>;
+				#size-cells = <0>;
 				reg = <0x02184200 0x200>;
 				interrupts = <0 40 IRQ_TYPE_LEVEL_HIGH>;
 				clocks = <&clks IMX6QDL_CLK_USBOH3>;
@@ -959,6 +961,8 @@
 
 			usbh2: usb@02184400 {
 				compatible = "fsl,imx6q-usb", "fsl,imx27-usb";
+				#address-cells = <1>;
+				#size-cells = <0>;
 				reg = <0x02184400 0x200>;
 				interrupts = <0 41 IRQ_TYPE_LEVEL_HIGH>;
 				clocks = <&clks IMX6QDL_CLK_USBOH3>;
@@ -972,6 +976,8 @@
 
 			usbh3: usb@02184600 {
 				compatible = "fsl,imx6q-usb", "fsl,imx27-usb";
+				#address-cells = <1>;
+				#size-cells = <0>;
 				reg = <0x02184600 0x200>;
 				interrupts = <0 42 IRQ_TYPE_LEVEL_HIGH>;
 				clocks = <&clks IMX6QDL_CLK_USBOH3>;
-- 
2.7.4

[PATCH v15 6/7] ARM: dts: imx6qdl-udoo.dtsi: fix onboard USB HUB property

[Peter Chen]

The current dts describes USB HUB's property at USB controller's
entry, it is improper. The USB HUB should be the child node
under USB controller, and power sequence properties are under
it. Besides, using gpio pinctrl setting for USB2415's reset pin.

Signed-off-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Joshua Clayton <stillcompiling@gmail.com>
Tested-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
---
 arch/arm/boot/dts/imx6qdl-udoo.dtsi | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/arch/arm/boot/dts/imx6qdl-udoo.dtsi b/arch/arm/boot/dts/imx6qdl-udoo.dtsi
index c96c91d..a173de2 100644
--- a/arch/arm/boot/dts/imx6qdl-udoo.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-udoo.dtsi
@@ -9,6 +9,8 @@
  *
  */
 
+#include <dt-bindings/gpio/gpio.h>
+
 / {
 	aliases {
 		backlight = &backlight;
@@ -58,17 +60,6 @@
 		#address-cells = <1>;
 		#size-cells = <0>;
 
-		reg_usb_h1_vbus: regulator@0 {
-			compatible = "regulator-fixed";
-			reg = <0>;
-			regulator-name = "usb_h1_vbus";
-			regulator-min-microvolt = <5000000>;
-			regulator-max-microvolt = <5000000>;
-			enable-active-high;
-			startup-delay-us = <2>; /* USB2415 requires a POR of 1 us minimum */
-			gpio = <&gpio7 12 0>;
-		};
-
 		reg_panel: regulator@1 {
 			compatible = "regulator-fixed";
 			reg = <1>;
@@ -188,7 +179,7 @@
 
 		pinctrl_usbh: usbhgrp {
 			fsl,pins = <
-				MX6QDL_PAD_GPIO_17__GPIO7_IO12 0x80000000
+				MX6QDL_PAD_GPIO_17__GPIO7_IO12	0x1b0b0
 				MX6QDL_PAD_NANDF_CS2__CCM_CLKO2 0x130b0
 			>;
 		};
@@ -259,9 +250,16 @@
 &usbh1 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_usbh>;
-	vbus-supply = <&reg_usb_h1_vbus>;
-	clocks = <&clks IMX6QDL_CLK_CKO>;
 	status = "okay";
+
+	usb2415: hub@1 {
+		compatible = "usb424,2514";
+		reg = <1>;
+
+		clocks = <&clks IMX6QDL_CLK_CKO>;
+		reset-gpios = <&gpio7 12 GPIO_ACTIVE_LOW>;
+		reset-duration-us = <3000>;
+	};
 };
 
 &usdhc3 {
-- 
2.7.4

[PATCH v15 7/7] ARM: dts: imx6q-evi: Fix onboard hub reset line

[Peter Chen]

From: Joshua Clayton <stillcompiling@gmail.com>

Previously the onboard hub was made to work by treating its
reset gpio as a regulator enable.
Get rid of that kludge now that pwseq has added reset gpio support
Move pin muxing the hub reset pin into the usbh1 group

Signed-off-by: Joshua Clayton <stillcompiling@gmail.com>
Signed-off-by: Peter Chen <peter.chen@nxp.com>
---
 arch/arm/boot/dts/imx6q-evi.dts | 25 +++++++------------------
 1 file changed, 7 insertions(+), 18 deletions(-)

diff --git a/arch/arm/boot/dts/imx6q-evi.dts b/arch/arm/boot/dts/imx6q-evi.dts
index fd2220a..24fe093 100644
--- a/arch/arm/boot/dts/imx6q-evi.dts
+++ b/arch/arm/boot/dts/imx6q-evi.dts
@@ -54,18 +54,6 @@
 		reg = <0x10000000 0x40000000>;
 	};
 
-	reg_usbh1_vbus: regulator-usbhubreset {
-		compatible = "regulator-fixed";
-		regulator-name = "usbh1_vbus";
-		regulator-min-microvolt = <5000000>;
-		regulator-max-microvolt = <5000000>;
-		enable-active-high;
-		startup-delay-us = <2>;
-		pinctrl-names = "default";
-		pinctrl-0 = <&pinctrl_usbh1_hubreset>;
-		gpio = <&gpio7 12 GPIO_ACTIVE_HIGH>;
-	};
-
 	reg_usb_otg_vbus: regulator-usbotgvbus {
 		compatible = "regulator-fixed";
 		regulator-name = "usb_otg_vbus";
@@ -204,12 +192,18 @@
 };
 
 &usbh1 {
-	vbus-supply = <&reg_usbh1_vbus>;
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_usbh1>;
 	dr_mode = "host";
 	disable-over-current;
 	status = "okay";
+
+	usb2415host: hub@1 {
+		compatible = "usb424,2513";
+		reg = <1>;
+		reset-gpios = <&gpio7 12 GPIO_ACTIVE_LOW>;
+		reset-duration-us = <3000>;
+	};
 };
 
 &usbotg {
@@ -465,11 +459,6 @@
 			MX6QDL_PAD_GPIO_3__USB_H1_OC 0x1b0b0
 			/* usbh1_b OC */
 			MX6QDL_PAD_GPIO_0__GPIO1_IO00 0x1b0b0
-		>;
-	};
-
-	pinctrl_usbh1_hubreset: usbh1hubresetgrp {
-		fsl,pins = <
 			MX6QDL_PAD_GPIO_17__GPIO7_IO12 0x1b0b0
 		>;
 	};
-- 
2.7.4

Re: [PATCH v15 2/7] power: add power sequence library

[Ulf Hansson]

[...]

> +
> +/**
> + * of_pwrseq_on - Carry out power sequence on for device node
> + *
> + * @np: the device node would like to power on
> + *
> + * Carry out a single device power on.  If multiple devices
> + * need to be handled, use of_pwrseq_on_list() instead.
> + *
> + * Return a pointer to the power sequence instance on success,
> + * or an error code otherwise.
> + */
> +struct pwrseq *of_pwrseq_on(struct device_node *np)
> +{
> +       struct pwrseq *pwrseq;
> +       int ret;
> +
> +       pwrseq = pwrseq_find_available_instance(np);
> +       if (!pwrseq)
> +               return ERR_PTR(-ENOENT);

In case the pwrseq instance hasn't been registered yet, then there is
no way to deal with -EPROBE_DEFER properly here.

I haven't been following the discussions in-depth during all
iterations, so perhaps you have already discussed why doing it like
this.

Anyway, that means all pwrseq instances needs to be registered an
early boot level, to be safe. To me, that seems like poor design
choice.

[...]

Otherwise I think this looks okay to me.

Kind regards
Uffe

Re: [PATCH v15 2/7] power: add power sequence library

[Peter Chen]

On Tue, Jun 13, 2017 at 12:24:42PM +0200, Ulf Hansson wrote:
> [...]
> 
> > +
> > +/**
> > + * of_pwrseq_on - Carry out power sequence on for device node
> > + *
> > + * @np: the device node would like to power on
> > + *
> > + * Carry out a single device power on.  If multiple devices
> > + * need to be handled, use of_pwrseq_on_list() instead.
> > + *
> > + * Return a pointer to the power sequence instance on success,
> > + * or an error code otherwise.
> > + */
> > +struct pwrseq *of_pwrseq_on(struct device_node *np)
> > +{
> > +       struct pwrseq *pwrseq;
> > +       int ret;
> > +
> > +       pwrseq = pwrseq_find_available_instance(np);
> > +       if (!pwrseq)
> > +               return ERR_PTR(-ENOENT);
> 
> In case the pwrseq instance hasn't been registered yet, then there is
> no way to deal with -EPROBE_DEFER properly here.
> 
> I haven't been following the discussions in-depth during all
> iterations, so perhaps you have already discussed why doing it like
> this.

Yes, it has been discussed. In order to compare with compatible string
at dts, we need to have one registered pwrseq instance for each
pwrseq library, this pre-registered one is allocated using
postcore_initcall, and the new (eg, second) instance is registered
after pwrseq_get has succeeded.

Peter

> 
> Anyway, that means all pwrseq instances needs to be registered an
> early boot level, to be safe. To me, that seems like poor design
> choice.
> 
> Otherwise I think this looks okay to me.
> 

-- 

Best Regards,
Peter Chen

Re: [PATCH v15 2/7] power: add power sequence library

[Ulf Hansson]

On 14 June 2017 at 03:53, Peter Chen <hzpeterchen@gmail.com> wrote:
> On Tue, Jun 13, 2017 at 12:24:42PM +0200, Ulf Hansson wrote:
>> [...]
>>
>> > +
>> > +/**
>> > + * of_pwrseq_on - Carry out power sequence on for device node
>> > + *
>> > + * @np: the device node would like to power on
>> > + *
>> > + * Carry out a single device power on.  If multiple devices
>> > + * need to be handled, use of_pwrseq_on_list() instead.
>> > + *
>> > + * Return a pointer to the power sequence instance on success,
>> > + * or an error code otherwise.
>> > + */
>> > +struct pwrseq *of_pwrseq_on(struct device_node *np)
>> > +{
>> > +       struct pwrseq *pwrseq;
>> > +       int ret;
>> > +
>> > +       pwrseq = pwrseq_find_available_instance(np);
>> > +       if (!pwrseq)
>> > +               return ERR_PTR(-ENOENT);
>>
>> In case the pwrseq instance hasn't been registered yet, then there is
>> no way to deal with -EPROBE_DEFER properly here.
>>
>> I haven't been following the discussions in-depth during all
>> iterations, so perhaps you have already discussed why doing it like
>> this.
>
> Yes, it has been discussed. In order to compare with compatible string
> at dts, we need to have one registered pwrseq instance for each
> pwrseq library, this pre-registered one is allocated using
> postcore_initcall, and the new (eg, second) instance is registered
> after pwrseq_get has succeeded.

I understand you need one compatible per pwrseq library, but how does
that have anything to do with -EPROBE_DEFER?

My point is that, if a driver calls of_pwrseq_on() (which calls
pwrseq_find_available_instance()), but the corresponding pwrseq
library and instance has not yet been registered for that device. Then
how will you handle -EPROBE_DEFER? I guess you simply can't, which is
why *all* pwrseq libraries needs to be registered in early boot phase,
like at postcore_initcall(). Right?

If that is the case, I really don't like it.

Moreover, I have found yet another severe problem but reviewing the code:
In the struct pwrseq, you have a "bool used", which you are setting to
"true" once the pwrseq has been hooked up with the device, when a
driver calls of_pwrseq_on(). Setting that variable to true, will also
prevent another driver from using the same instance of the pwrseq for
its device. So, to cope with multiple users, you register a new
instance of the same pwrseq library that got hooked up, once the
->get() callback is about to complete.

The problem the occurs, when there is another driver calling
of_pwrseq_on() in between, meaning that the new instance has not yet
been registered. This will simply fail, won't it?

Sorry for jumping in late, however to me it seems like there is still
some pieces missing to make this work.

[...]

Kind regards
Uffe

Re: [PATCH v15 2/7] power: add power sequence library

[Peter Chen]

On Wed, Jun 14, 2017 at 10:53:29AM +0200, Ulf Hansson wrote:
> On 14 June 2017 at 03:53, Peter Chen <hzpeterchen@gmail.com> wrote:
> > On Tue, Jun 13, 2017 at 12:24:42PM +0200, Ulf Hansson wrote:
> >> [...]
> >>
> >> > +
> >> > +/**
> >> > + * of_pwrseq_on - Carry out power sequence on for device node
> >> > + *
> >> > + * @np: the device node would like to power on
> >> > + *
> >> > + * Carry out a single device power on.  If multiple devices
> >> > + * need to be handled, use of_pwrseq_on_list() instead.
> >> > + *
> >> > + * Return a pointer to the power sequence instance on success,
> >> > + * or an error code otherwise.
> >> > + */
> >> > +struct pwrseq *of_pwrseq_on(struct device_node *np)
> >> > +{
> >> > +       struct pwrseq *pwrseq;
> >> > +       int ret;
> >> > +
> >> > +       pwrseq = pwrseq_find_available_instance(np);
> >> > +       if (!pwrseq)
> >> > +               return ERR_PTR(-ENOENT);
> >>
> >> In case the pwrseq instance hasn't been registered yet, then there is
> >> no way to deal with -EPROBE_DEFER properly here.
> >>
> >> I haven't been following the discussions in-depth during all
> >> iterations, so perhaps you have already discussed why doing it like
> >> this.
> >
> > Yes, it has been discussed. In order to compare with compatible string
> > at dts, we need to have one registered pwrseq instance for each
> > pwrseq library, this pre-registered one is allocated using
> > postcore_initcall, and the new (eg, second) instance is registered
> > after pwrseq_get has succeeded.
> 
> I understand you need one compatible per pwrseq library, but how does
> that have anything to do with -EPROBE_DEFER?
> 
> My point is that, if a driver calls of_pwrseq_on() (which calls
> pwrseq_find_available_instance()), but the corresponding pwrseq
> library and instance has not yet been registered for that device. Then
> how will you handle -EPROBE_DEFER? I guess you simply can't, which is
> why *all* pwrseq libraries needs to be registered in early boot phase,
> like at postcore_initcall(). Right?
> 
> If that is the case, I really don't like it.
> 

Yes, you are right. This is the limitation for this power sequence
library, the registration for the 1st power sequence instance must
be finished before device driver uses it. I am appreciated that
you can supply some suggestions for it.

> Moreover, I have found yet another severe problem but reviewing the code:
> In the struct pwrseq, you have a "bool used", which you are setting to
> "true" once the pwrseq has been hooked up with the device, when a
> driver calls of_pwrseq_on(). Setting that variable to true, will also
> prevent another driver from using the same instance of the pwrseq for
> its device. So, to cope with multiple users, you register a new
> instance of the same pwrseq library that got hooked up, once the
> ->get() callback is about to complete.
> 
> The problem the occurs, when there is another driver calling
> of_pwrseq_on() in between, meaning that the new instance has not yet
> been registered. This will simply fail, won't it?

Yes, you are right, thanks for pointing that, I will add mutex_lock for
of_pwrseq_on.

> 
> Sorry for jumping in late, however to me it seems like there is still
> some pieces missing to make this work.
> 
> [...]
> 
> Kind regards
> Uffe

-- 

Best Regards,
Peter Chen

Re: [PATCH v15 2/7] power: add power sequence library

[Ulf Hansson]

On 15 June 2017 at 08:58, Peter Chen <hzpeterchen@gmail.com> wrote:
> On Wed, Jun 14, 2017 at 10:53:29AM +0200, Ulf Hansson wrote:
>> On 14 June 2017 at 03:53, Peter Chen <hzpeterchen@gmail.com> wrote:
>> > On Tue, Jun 13, 2017 at 12:24:42PM +0200, Ulf Hansson wrote:
>> >> [...]
>> >>
>> >> > +
>> >> > +/**
>> >> > + * of_pwrseq_on - Carry out power sequence on for device node
>> >> > + *
>> >> > + * @np: the device node would like to power on
>> >> > + *
>> >> > + * Carry out a single device power on.  If multiple devices
>> >> > + * need to be handled, use of_pwrseq_on_list() instead.
>> >> > + *
>> >> > + * Return a pointer to the power sequence instance on success,
>> >> > + * or an error code otherwise.
>> >> > + */
>> >> > +struct pwrseq *of_pwrseq_on(struct device_node *np)
>> >> > +{
>> >> > +       struct pwrseq *pwrseq;
>> >> > +       int ret;
>> >> > +
>> >> > +       pwrseq = pwrseq_find_available_instance(np);
>> >> > +       if (!pwrseq)
>> >> > +               return ERR_PTR(-ENOENT);
>> >>
>> >> In case the pwrseq instance hasn't been registered yet, then there is
>> >> no way to deal with -EPROBE_DEFER properly here.
>> >>
>> >> I haven't been following the discussions in-depth during all
>> >> iterations, so perhaps you have already discussed why doing it like
>> >> this.
>> >
>> > Yes, it has been discussed. In order to compare with compatible string
>> > at dts, we need to have one registered pwrseq instance for each
>> > pwrseq library, this pre-registered one is allocated using
>> > postcore_initcall, and the new (eg, second) instance is registered
>> > after pwrseq_get has succeeded.
>>
>> I understand you need one compatible per pwrseq library, but how does
>> that have anything to do with -EPROBE_DEFER?
>>
>> My point is that, if a driver calls of_pwrseq_on() (which calls
>> pwrseq_find_available_instance()), but the corresponding pwrseq
>> library and instance has not yet been registered for that device. Then
>> how will you handle -EPROBE_DEFER? I guess you simply can't, which is
>> why *all* pwrseq libraries needs to be registered in early boot phase,
>> like at postcore_initcall(). Right?
>>
>> If that is the case, I really don't like it.
>>
>
> Yes, you are right. This is the limitation for this power sequence
> library, the registration for the 1st power sequence instance must
> be finished before device driver uses it. I am appreciated that
> you can supply some suggestions for it.

In general this kind of problems is solved by first parsing the DTB,
which means you will find out whether there is a resource (a pwrseq)
required for the device. Then you try to fetch that resource, and if
that fails, it means the resource is not yet available, and hence you
want to retry later and should return -EPROBE_DEFER.

In this case, of_pwrseq_on() needs to be converted to start looking
for a pwrseq compatible in it's child node - I guess. Then if that is
found, you try to fetch the instance of the corresponding library.
Failing to fetch the library instance should then cause a return
-EPROBE_DEFER.

>
>> Moreover, I have found yet another severe problem but reviewing the code:
>> In the struct pwrseq, you have a "bool used", which you are setting to
>> "true" once the pwrseq has been hooked up with the device, when a
>> driver calls of_pwrseq_on(). Setting that variable to true, will also
>> prevent another driver from using the same instance of the pwrseq for
>> its device. So, to cope with multiple users, you register a new
>> instance of the same pwrseq library that got hooked up, once the
>> ->get() callback is about to complete.
>>
>> The problem the occurs, when there is another driver calling
>> of_pwrseq_on() in between, meaning that the new instance has not yet
>> been registered. This will simply fail, won't it?
>
> Yes, you are right, thanks for pointing that, I will add mutex_lock for
> of_pwrseq_on.

Another option is to entirely skip to two step approach.

In other words, make the library to cope with multiple users via the
same registered library instance.

[...]

Kind regards
Uffe

Re: [PATCH v15 2/7] power: add power sequence library

[Peter Chen]

On Thu, Jun 15, 2017 at 10:11:45AM +0200, Ulf Hansson wrote:
> > Yes, you are right. This is the limitation for this power sequence
> > library, the registration for the 1st power sequence instance must
> > be finished before device driver uses it. I am appreciated that
> > you can supply some suggestions for it.
> 
> In general this kind of problems is solved by first parsing the DTB,
> which means you will find out whether there is a resource (a pwrseq)
> required for the device. Then you try to fetch that resource, and if
> that fails, it means the resource is not yet available, and hence you
> want to retry later and should return -EPROBE_DEFER.
> 
> In this case, of_pwrseq_on() needs to be converted to start looking
> for a pwrseq compatible in it's child node - I guess. Then if that is
> found, you try to fetch the instance of the corresponding library.
> Failing to fetch the library instance should then cause a return
> -EPROBE_DEFER.

The most difficulty for this is we can't know whether the requested
pwrseq instance will be registered or not, the kernel configuration
for this pwrseq library may not be chosen at all.

> 
> >
> >> Moreover, I have found yet another severe problem but reviewing the code:
> >> In the struct pwrseq, you have a "bool used", which you are setting to
> >> "true" once the pwrseq has been hooked up with the device, when a
> >> driver calls of_pwrseq_on(). Setting that variable to true, will also
> >> prevent another driver from using the same instance of the pwrseq for
> >> its device. So, to cope with multiple users, you register a new
> >> instance of the same pwrseq library that got hooked up, once the
> >> ->get() callback is about to complete.
> >>
> >> The problem the occurs, when there is another driver calling
> >> of_pwrseq_on() in between, meaning that the new instance has not yet
> >> been registered. This will simply fail, won't it?
> >
> > Yes, you are right, thanks for pointing that, I will add mutex_lock for
> > of_pwrseq_on.
> 
> Another option is to entirely skip to two step approach.
> 
> In other words, make the library to cope with multiple users via the
> same registered library instance.
> 

No, the pwrseq instance stores dtb information (clock, gpio, etc), it
needs to be per device.

-- 

Best Regards,
Peter Chen

Re: [PATCH v15 2/7] power: add power sequence library

[Ulf Hansson]

On 15 June 2017 at 11:11, Peter Chen <hzpeterchen@gmail.com> wrote:
> On Thu, Jun 15, 2017 at 10:11:45AM +0200, Ulf Hansson wrote:
>> > Yes, you are right. This is the limitation for this power sequence
>> > library, the registration for the 1st power sequence instance must
>> > be finished before device driver uses it. I am appreciated that
>> > you can supply some suggestions for it.
>>
>> In general this kind of problems is solved by first parsing the DTB,
>> which means you will find out whether there is a resource (a pwrseq)
>> required for the device. Then you try to fetch that resource, and if
>> that fails, it means the resource is not yet available, and hence you
>> want to retry later and should return -EPROBE_DEFER.
>>
>> In this case, of_pwrseq_on() needs to be converted to start looking
>> for a pwrseq compatible in it's child node - I guess. Then if that is
>> found, you try to fetch the instance of the corresponding library.
>> Failing to fetch the library instance should then cause a return
>> -EPROBE_DEFER.
>
> The most difficulty for this is we can't know whether the requested
> pwrseq instance will be registered or not, the kernel configuration
> for this pwrseq library may not be chosen at all.

In such case it is still correct to return -EPROBE_DEFER, because the
driver that tries to probe its device will fail unless it can run the
needed pwrseq. Right?

>
>>
>> >
>> >> Moreover, I have found yet another severe problem but reviewing the code:
>> >> In the struct pwrseq, you have a "bool used", which you are setting to
>> >> "true" once the pwrseq has been hooked up with the device, when a
>> >> driver calls of_pwrseq_on(). Setting that variable to true, will also
>> >> prevent another driver from using the same instance of the pwrseq for
>> >> its device. So, to cope with multiple users, you register a new
>> >> instance of the same pwrseq library that got hooked up, once the
>> >> ->get() callback is about to complete.
>> >>
>> >> The problem the occurs, when there is another driver calling
>> >> of_pwrseq_on() in between, meaning that the new instance has not yet
>> >> been registered. This will simply fail, won't it?
>> >
>> > Yes, you are right, thanks for pointing that, I will add mutex_lock for
>> > of_pwrseq_on.
>>
>> Another option is to entirely skip to two step approach.
>>
>> In other words, make the library to cope with multiple users via the
>> same registered library instance.
>>
>
> No, the pwrseq instance stores dtb information (clock, gpio, etc), it
> needs to be per device.

I think you misunderstood my suggestion here. Of course you need to
allocate one pwrseq data per device.

However, my point is that you shouldn't need more than one instance of
the library functions to be registered in the list of available pwrseq
libraries.

Kind regards
Uffe

Re: [PATCH v15 2/7] power: add power sequence library

[Peter Chen]

On Thu, Jun 15, 2017 at 11:35:20AM +0200, Ulf Hansson wrote:
> On 15 June 2017 at 11:11, Peter Chen <hzpeterchen@gmail.com> wrote:
> > On Thu, Jun 15, 2017 at 10:11:45AM +0200, Ulf Hansson wrote:
> >> > Yes, you are right. This is the limitation for this power sequence
> >> > library, the registration for the 1st power sequence instance must
> >> > be finished before device driver uses it. I am appreciated that
> >> > you can supply some suggestions for it.
> >>
> >> In general this kind of problems is solved by first parsing the DTB,
> >> which means you will find out whether there is a resource (a pwrseq)
> >> required for the device. Then you try to fetch that resource, and if
> >> that fails, it means the resource is not yet available, and hence you
> >> want to retry later and should return -EPROBE_DEFER.
> >>
> >> In this case, of_pwrseq_on() needs to be converted to start looking
> >> for a pwrseq compatible in it's child node - I guess. Then if that is
> >> found, you try to fetch the instance of the corresponding library.
> >> Failing to fetch the library instance should then cause a return
> >> -EPROBE_DEFER.
> >
> > The most difficulty for this is we can't know whether the requested
> > pwrseq instance will be registered or not, the kernel configuration
> > for this pwrseq library may not be chosen at all.
> 
> In such case it is still correct to return -EPROBE_DEFER, because the
> driver that tries to probe its device will fail unless it can run the
> needed pwrseq. Right?
> 

Unlike the MMC design, there is no dts entry to indicate whether this
device needs pwrseq or not at this design, it will only carry out power
on sequence after matching. So, return -EPROBE_DEFER may not work since
this device may never need pwrseq.

> >
> >>
> >> >
> >> >> Moreover, I have found yet another severe problem but reviewing the code:
> >> >> In the struct pwrseq, you have a "bool used", which you are setting to
> >> >> "true" once the pwrseq has been hooked up with the device, when a
> >> >> driver calls of_pwrseq_on(). Setting that variable to true, will also
> >> >> prevent another driver from using the same instance of the pwrseq for
> >> >> its device. So, to cope with multiple users, you register a new
> >> >> instance of the same pwrseq library that got hooked up, once the
> >> >> ->get() callback is about to complete.
> >> >>
> >> >> The problem the occurs, when there is another driver calling
> >> >> of_pwrseq_on() in between, meaning that the new instance has not yet
> >> >> been registered. This will simply fail, won't it?
> >> >
> >> > Yes, you are right, thanks for pointing that, I will add mutex_lock for
> >> > of_pwrseq_on.
> >>
> >> Another option is to entirely skip to two step approach.
> >>
> >> In other words, make the library to cope with multiple users via the
> >> same registered library instance.
> >>
> >
> > No, the pwrseq instance stores dtb information (clock, gpio, etc), it
> > needs to be per device.
> 
> I think you misunderstood my suggestion here. Of course you need to
> allocate one pwrseq data per device.
> 
> However, my point is that you shouldn't need more than one instance of
> the library functions to be registered in the list of available pwrseq
> libraries.
> 

This additional instance is used to store compatible information for
this pwrseq library, it is used for the next matching between device
and pwrseq library, it just likes we need the first pwrseq instance
registered at boot stage.

-- 

Best Regards,
Peter Chen

Re: [PATCH v15 2/7] power: add power sequence library

[Peter Chen]

On Thu, Jun 15, 2017 at 06:06:04PM +0800, Peter Chen wrote:
> On Thu, Jun 15, 2017 at 11:35:20AM +0200, Ulf Hansson wrote:
> > On 15 June 2017 at 11:11, Peter Chen <hzpeterchen@gmail.com> wrote:
> > > On Thu, Jun 15, 2017 at 10:11:45AM +0200, Ulf Hansson wrote:
> > >> > Yes, you are right. This is the limitation for this power sequence
> > >> > library, the registration for the 1st power sequence instance must
> > >> > be finished before device driver uses it. I am appreciated that
> > >> > you can supply some suggestions for it.
> > >>
> > >> In general this kind of problems is solved by first parsing the DTB,
> > >> which means you will find out whether there is a resource (a pwrseq)
> > >> required for the device. Then you try to fetch that resource, and if
> > >> that fails, it means the resource is not yet available, and hence you
> > >> want to retry later and should return -EPROBE_DEFER.
> > >>
> > >> In this case, of_pwrseq_on() needs to be converted to start looking
> > >> for a pwrseq compatible in it's child node - I guess. Then if that is
> > >> found, you try to fetch the instance of the corresponding library.
> > >> Failing to fetch the library instance should then cause a return
> > >> -EPROBE_DEFER.
> > >
> > > The most difficulty for this is we can't know whether the requested
> > > pwrseq instance will be registered or not, the kernel configuration
> > > for this pwrseq library may not be chosen at all.
> > 
> > In such case it is still correct to return -EPROBE_DEFER, because the
> > driver that tries to probe its device will fail unless it can run the
> > needed pwrseq. Right?
> > 
> 
> Unlike the MMC design, there is no dts entry to indicate whether this
> device needs pwrseq or not at this design, it will only carry out power
> on sequence after matching. So, return -EPROBE_DEFER may not work since
> this device may never need pwrseq.
> 

Ulf, since it is the use case limitation, it can't work like device
driver. Do you have more comments for it, thanks.

Peter


> > >
> > >>
> > >> >
> > >> >> Moreover, I have found yet another severe problem but reviewing the code:
> > >> >> In the struct pwrseq, you have a "bool used", which you are setting to
> > >> >> "true" once the pwrseq has been hooked up with the device, when a
> > >> >> driver calls of_pwrseq_on(). Setting that variable to true, will also
> > >> >> prevent another driver from using the same instance of the pwrseq for
> > >> >> its device. So, to cope with multiple users, you register a new
> > >> >> instance of the same pwrseq library that got hooked up, once the
> > >> >> ->get() callback is about to complete.
> > >> >>
> > >> >> The problem the occurs, when there is another driver calling
> > >> >> of_pwrseq_on() in between, meaning that the new instance has not yet
> > >> >> been registered. This will simply fail, won't it?
> > >> >
> > >> > Yes, you are right, thanks for pointing that, I will add mutex_lock for
> > >> > of_pwrseq_on.
> > >>
> > >> Another option is to entirely skip to two step approach.
> > >>
> > >> In other words, make the library to cope with multiple users via the
> > >> same registered library instance.
> > >>
> > >
> > > No, the pwrseq instance stores dtb information (clock, gpio, etc), it
> > > needs to be per device.
> > 
> > I think you misunderstood my suggestion here. Of course you need to
> > allocate one pwrseq data per device.
> > 
> > However, my point is that you shouldn't need more than one instance of
> > the library functions to be registered in the list of available pwrseq
> > libraries.
> > 
> 
> This additional instance is used to store compatible information for
> this pwrseq library, it is used for the next matching between device
> and pwrseq library, it just likes we need the first pwrseq instance
> registered at boot stage.
> 
> -- 
> 
> Best Regards,
> Peter Chen
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

-- 

Best Regards,
Peter Chen

Re: [PATCH v15 2/7] power: add power sequence library

[Ulf Hansson]

On 15 June 2017 at 12:06, Peter Chen <hzpeterchen@gmail.com> wrote:
> On Thu, Jun 15, 2017 at 11:35:20AM +0200, Ulf Hansson wrote:
>> On 15 June 2017 at 11:11, Peter Chen <hzpeterchen@gmail.com> wrote:
>> > On Thu, Jun 15, 2017 at 10:11:45AM +0200, Ulf Hansson wrote:
>> >> > Yes, you are right. This is the limitation for this power sequence
>> >> > library, the registration for the 1st power sequence instance must
>> >> > be finished before device driver uses it. I am appreciated that
>> >> > you can supply some suggestions for it.
>> >>
>> >> In general this kind of problems is solved by first parsing the DTB,
>> >> which means you will find out whether there is a resource (a pwrseq)
>> >> required for the device. Then you try to fetch that resource, and if
>> >> that fails, it means the resource is not yet available, and hence you
>> >> want to retry later and should return -EPROBE_DEFER.
>> >>
>> >> In this case, of_pwrseq_on() needs to be converted to start looking
>> >> for a pwrseq compatible in it's child node - I guess. Then if that is
>> >> found, you try to fetch the instance of the corresponding library.
>> >> Failing to fetch the library instance should then cause a return
>> >> -EPROBE_DEFER.
>> >
>> > The most difficulty for this is we can't know whether the requested
>> > pwrseq instance will be registered or not, the kernel configuration
>> > for this pwrseq library may not be chosen at all.
>>
>> In such case it is still correct to return -EPROBE_DEFER, because the
>> driver that tries to probe its device will fail unless it can run the
>> needed pwrseq. Right?
>>
>
> Unlike the MMC design, there is no dts entry to indicate whether this
> device needs pwrseq or not at this design, it will only carry out power
> on sequence after matching. So, return -EPROBE_DEFER may not work since
> this device may never need pwrseq.

Then, how will you really be able to fetch the correct pwrseq library
instance for the device node?

Suppose their is a *list* of pwrseq library instances available. In
pwrseq_find_available_instance() you call of_match_node(table, np).
The "table" there corresponds to the compatible for the pwrseq library
and the np is the device node provided by the caller of
of_pwrseq_on().

Why is this match done?

Why can't the match be done before trying to fetch a library instance
and then in a second step, really try to fetch the instance? If only
the second step fails, returning -EPROBE_DEFER can be done, no?

BTW, I didn't compatible for the generic pwrseq library being
documented in this series.

>
>> >
>> >>
>> >> >
>> >> >> Moreover, I have found yet another severe problem but reviewing the code:
>> >> >> In the struct pwrseq, you have a "bool used", which you are setting to
>> >> >> "true" once the pwrseq has been hooked up with the device, when a
>> >> >> driver calls of_pwrseq_on(). Setting that variable to true, will also
>> >> >> prevent another driver from using the same instance of the pwrseq for
>> >> >> its device. So, to cope with multiple users, you register a new
>> >> >> instance of the same pwrseq library that got hooked up, once the
>> >> >> ->get() callback is about to complete.
>> >> >>
>> >> >> The problem the occurs, when there is another driver calling
>> >> >> of_pwrseq_on() in between, meaning that the new instance has not yet
>> >> >> been registered. This will simply fail, won't it?
>> >> >
>> >> > Yes, you are right, thanks for pointing that, I will add mutex_lock for
>> >> > of_pwrseq_on.
>> >>
>> >> Another option is to entirely skip to two step approach.
>> >>
>> >> In other words, make the library to cope with multiple users via the
>> >> same registered library instance.
>> >>
>> >
>> > No, the pwrseq instance stores dtb information (clock, gpio, etc), it
>> > needs to be per device.
>>
>> I think you misunderstood my suggestion here. Of course you need to
>> allocate one pwrseq data per device.
>>
>> However, my point is that you shouldn't need more than one instance of
>> the library functions to be registered in the list of available pwrseq
>> libraries.
>>
>
> This additional instance is used to store compatible information for
> this pwrseq library, it is used for the next matching between device
> and pwrseq library, it just likes we need the first pwrseq instance
> registered at boot stage.

Why can't the compatible information be a static table, known by the
pwrseq core library?

Then when of_pwrseq_on() is called, that static table is parsed and
matched, then a corresponding pwrseq library instance tries to be
fetched.

Kind regards
Uffe

Re: [PATCH v15 2/7] power: add power sequence library

[Peter Chen]

On Mon, Jun 19, 2017 at 10:09:58AM +0200, Ulf Hansson wrote:
> On 15 June 2017 at 12:06, Peter Chen <hzpeterchen@gmail.com> wrote:
> > On Thu, Jun 15, 2017 at 11:35:20AM +0200, Ulf Hansson wrote:
> >> On 15 June 2017 at 11:11, Peter Chen <hzpeterchen@gmail.com> wrote:
> >> > On Thu, Jun 15, 2017 at 10:11:45AM +0200, Ulf Hansson wrote:
> >> >> > Yes, you are right. This is the limitation for this power sequence
> >> >> > library, the registration for the 1st power sequence instance must
> >> >> > be finished before device driver uses it. I am appreciated that
> >> >> > you can supply some suggestions for it.
> >> >>
> >> >> In general this kind of problems is solved by first parsing the DTB,
> >> >> which means you will find out whether there is a resource (a pwrseq)
> >> >> required for the device. Then you try to fetch that resource, and if
> >> >> that fails, it means the resource is not yet available, and hence you
> >> >> want to retry later and should return -EPROBE_DEFER.
> >> >>
> >> >> In this case, of_pwrseq_on() needs to be converted to start looking
> >> >> for a pwrseq compatible in it's child node - I guess. Then if that is
> >> >> found, you try to fetch the instance of the corresponding library.
> >> >> Failing to fetch the library instance should then cause a return
> >> >> -EPROBE_DEFER.
> >> >
> >> > The most difficulty for this is we can't know whether the requested
> >> > pwrseq instance will be registered or not, the kernel configuration
> >> > for this pwrseq library may not be chosen at all.
> >>
> >> In such case it is still correct to return -EPROBE_DEFER, because the
> >> driver that tries to probe its device will fail unless it can run the
> >> needed pwrseq. Right?
> >>
> >
> > Unlike the MMC design, there is no dts entry to indicate whether this
> > device needs pwrseq or not at this design, it will only carry out power
> > on sequence after matching. So, return -EPROBE_DEFER may not work since
> > this device may never need pwrseq.
> 
> Then, how will you really be able to fetch the correct pwrseq library
> instance for the device node?
> 
> Suppose their is a *list* of pwrseq library instances available. In
> pwrseq_find_available_instance() you call of_match_node(table, np).
> The "table" there corresponds to the compatible for the pwrseq library
> and the np is the device node provided by the caller of
> of_pwrseq_on().
> 
> Why is this match done?

The compatible in table is from the source code, and the compatible in
np is from the dts. This is the current match way, I comment your
suggestion below.

> 
> Why can't the match be done before trying to fetch a library instance

How? If there is no pwrseq instance, how can we do match?

> and then in a second step, really try to fetch the instance? If only
> the second step fails, returning -EPROBE_DEFER can be done, no?
> 
> BTW, I didn't compatible for the generic pwrseq library being
> documented in this series.
> 
> >
> >> >
> >> >>
> >> >> >
> >> >> >> Moreover, I have found yet another severe problem but reviewing the code:
> >> >> >> In the struct pwrseq, you have a "bool used", which you are setting to
> >> >> >> "true" once the pwrseq has been hooked up with the device, when a
> >> >> >> driver calls of_pwrseq_on(). Setting that variable to true, will also
> >> >> >> prevent another driver from using the same instance of the pwrseq for
> >> >> >> its device. So, to cope with multiple users, you register a new
> >> >> >> instance of the same pwrseq library that got hooked up, once the
> >> >> >> ->get() callback is about to complete.
> >> >> >>
> >> >> >> The problem the occurs, when there is another driver calling
> >> >> >> of_pwrseq_on() in between, meaning that the new instance has not yet
> >> >> >> been registered. This will simply fail, won't it?
> >> >> >
> >> >> > Yes, you are right, thanks for pointing that, I will add mutex_lock for
> >> >> > of_pwrseq_on.
> >> >>
> >> >> Another option is to entirely skip to two step approach.
> >> >>
> >> >> In other words, make the library to cope with multiple users via the
> >> >> same registered library instance.
> >> >>
> >> >
> >> > No, the pwrseq instance stores dtb information (clock, gpio, etc), it
> >> > needs to be per device.
> >>
> >> I think you misunderstood my suggestion here. Of course you need to
> >> allocate one pwrseq data per device.
> >>
> >> However, my point is that you shouldn't need more than one instance of
> >> the library functions to be registered in the list of available pwrseq
> >> libraries.
> >>
> >
> > This additional instance is used to store compatible information for
> > this pwrseq library, it is used for the next matching between device
> > and pwrseq library, it just likes we need the first pwrseq instance
> > registered at boot stage.
> 
> Why can't the compatible information be a static table, known by the
> pwrseq core library?
> 
> Then when of_pwrseq_on() is called, that static table is parsed and
> matched, then a corresponding pwrseq library instance tries to be
> fetched.
> 

So, you suggest allocating and registering pwrseq instance on the
demand? Eg, we maintain a power sequence static table, including
compatible and allocate function.

static const struct pwrseq_match_table pwrseq_match_table_list[] = {
	{ PWRSEQ_DEV(0x0204, 0x6025), .alloc_instance = pwrseq_AA_alloc_instance },
	{ PWRSEQ_DEV(0x0204, 0x6026), .alloc_instance = pwrseq_BB_alloc_instance },
	{ PWRSEQ_DEV(0xffff, 0xffff), .alloc_instance = pwrseq_generic_alloc_instance },
};

And pwrseq_AA{BB}_alloc_instance are defined at each pwrseq library, and
are exported.

Since the pwrseq_match_table_list is static, we can always do match, and
will not return -EPROBE_DEFER anymore, one problem for this is we need
always compile all pwrseq libraries. Any good suggestions?

-- 

Best Regards,
Peter Chen

Re: [PATCH v15 2/7] power: add power sequence library

[Ulf Hansson]

[...]

>> >
>> > Unlike the MMC design, there is no dts entry to indicate whether this
>> > device needs pwrseq or not at this design, it will only carry out power
>> > on sequence after matching. So, return -EPROBE_DEFER may not work since
>> > this device may never need pwrseq.
>>
>> Then, how will you really be able to fetch the correct pwrseq library
>> instance for the device node?
>>
>> Suppose their is a *list* of pwrseq library instances available. In
>> pwrseq_find_available_instance() you call of_match_node(table, np).
>> The "table" there corresponds to the compatible for the pwrseq library
>> and the np is the device node provided by the caller of
>> of_pwrseq_on().
>>
>> Why is this match done?
>
> The compatible in table is from the source code, and the compatible in
> np is from the dts. This is the current match way, I comment your
> suggestion below.
>
>>
>> Why can't the match be done before trying to fetch a library instance
>
> How? If there is no pwrseq instance, how can we do match?
>
>> and then in a second step, really try to fetch the instance? If only
>> the second step fails, returning -EPROBE_DEFER can be done, no?
>>
>> BTW, I didn't compatible for the generic pwrseq library being
>> documented in this series.

Seems like you need to update the DT documentation for the below
compatible, which is used for the generic pwrseq library. Perhaps this
is what puzzles me a bit on *why* the match is done.

+static const struct of_device_id generic_id_table[] = {
+       { .compatible = "generic",},
+       { /* sentinel */ }
+};

[...]

>> >
>> > This additional instance is used to store compatible information for
>> > this pwrseq library, it is used for the next matching between device
>> > and pwrseq library, it just likes we need the first pwrseq instance
>> > registered at boot stage.
>>
>> Why can't the compatible information be a static table, known by the
>> pwrseq core library?
>>
>> Then when of_pwrseq_on() is called, that static table is parsed and
>> matched, then a corresponding pwrseq library instance tries to be
>> fetched.
>>
>
> So, you suggest allocating and registering pwrseq instance on the
> demand? Eg, we maintain a power sequence static table, including
> compatible and allocate function.

Yes, something like that.

>
> static const struct pwrseq_match_table pwrseq_match_table_list[] = {
>         { PWRSEQ_DEV(0x0204, 0x6025), .alloc_instance = pwrseq_AA_alloc_instance },
>         { PWRSEQ_DEV(0x0204, 0x6026), .alloc_instance = pwrseq_BB_alloc_instance },
>         { PWRSEQ_DEV(0xffff, 0xffff), .alloc_instance = pwrseq_generic_alloc_instance },

What does the  PWRSEQ_DEV() macro do?

> };
>
> And pwrseq_AA{BB}_alloc_instance are defined at each pwrseq library, and
> are exported.

With "exported", I guess you mean shared via a common pwrseq header?

>
> Since the pwrseq_match_table_list is static, we can always do match, and
> will not return -EPROBE_DEFER anymore, one problem for this is we need
> always compile all pwrseq libraries. Any good suggestions?

You never returned -EPROBE_DEFER in the first case. That's why I complained. :-)

So, in case the OF match doesn't succeed, there are no reason to
propagate an error, but instead just bail out and returning 0 to the
caller.

If the OF match succeeds, it means the device requires a pwrseq
library to be used. Then, pwrseq_XX_alloc_instance() will be called,
on demand and which tries to fetch the resources (clocks, gpios etc).
If any of those attempts fetching a resource fails, its corresponding
error code should be propagated to the caller - including
-EPROBE_DEFER.

Regarding the "always compile all pwrseq libraries"; no we don't need
to do that. Instead we only need a to have a stub function for
pwrseq_XX_alloc_instance, in case its corresponding Kconfig option is
unset. That stub, should of course return an error code.

Kind regards
Uffe

Re: [PATCH v15 2/7] power: add power sequence library

[Peter Chen]

On Mon, Jun 19, 2017 at 11:48:05AM +0200, Ulf Hansson wrote:
> [...]
> 
> >> >
> >> > Unlike the MMC design, there is no dts entry to indicate whether this
> >> > device needs pwrseq or not at this design, it will only carry out power
> >> > on sequence after matching. So, return -EPROBE_DEFER may not work since
> >> > this device may never need pwrseq.
> >>
> >> Then, how will you really be able to fetch the correct pwrseq library
> >> instance for the device node?
> >>
> >> Suppose their is a *list* of pwrseq library instances available. In
> >> pwrseq_find_available_instance() you call of_match_node(table, np).
> >> The "table" there corresponds to the compatible for the pwrseq library
> >> and the np is the device node provided by the caller of
> >> of_pwrseq_on().
> >>
> >> Why is this match done?
> >
> > The compatible in table is from the source code, and the compatible in
> > np is from the dts. This is the current match way, I comment your
> > suggestion below.
> >
> >>
> >> Why can't the match be done before trying to fetch a library instance
> >
> > How? If there is no pwrseq instance, how can we do match?
> >
> >> and then in a second step, really try to fetch the instance? If only
> >> the second step fails, returning -EPROBE_DEFER can be done, no?
> >>
> >> BTW, I didn't compatible for the generic pwrseq library being
> >> documented in this series.
> 
> Seems like you need to update the DT documentation for the below
> compatible, which is used for the generic pwrseq library. Perhaps this
> is what puzzles me a bit on *why* the match is done.
> 
> +static const struct of_device_id generic_id_table[] = {
> +       { .compatible = "generic",},
> +       { /* sentinel */ }
> +};

Sorry, I should update this "generic" compatible at 1st binding-doc
patch.

> 
> [...]
> 
> >> >
> >> > This additional instance is used to store compatible information for
> >> > this pwrseq library, it is used for the next matching between device
> >> > and pwrseq library, it just likes we need the first pwrseq instance
> >> > registered at boot stage.
> >>
> >> Why can't the compatible information be a static table, known by the
> >> pwrseq core library?
> >>
> >> Then when of_pwrseq_on() is called, that static table is parsed and
> >> matched, then a corresponding pwrseq library instance tries to be
> >> fetched.
> >>
> >
> > So, you suggest allocating and registering pwrseq instance on the
> > demand? Eg, we maintain a power sequence static table, including
> > compatible and allocate function.
> 
> Yes, something like that.
> 
> >
> > static const struct pwrseq_match_table pwrseq_match_table_list[] = {
> >         { PWRSEQ_DEV(0x0204, 0x6025), .alloc_instance = pwrseq_AA_alloc_instance },
> >         { PWRSEQ_DEV(0x0204, 0x6026), .alloc_instance = pwrseq_BB_alloc_instance },
> >         { PWRSEQ_DEV(0xffff, 0xffff), .alloc_instance = pwrseq_generic_alloc_instance },
> 
> What does the  PWRSEQ_DEV() macro do?

In fact, this should be compatible string, I exampled it as USB vid,pid
wrongly.

> > Since the pwrseq_match_table_list is static, we can always do match, and
> > will not return -EPROBE_DEFER anymore, one problem for this is we need
> > always compile all pwrseq libraries. Any good suggestions?
> 
> You never returned -EPROBE_DEFER in the first case. That's why I complained. :-)
> 
> So, in case the OF match doesn't succeed, there are no reason to
> propagate an error, but instead just bail out and returning 0 to the
> caller.
> 
> If the OF match succeeds, it means the device requires a pwrseq
> library to be used. Then, pwrseq_XX_alloc_instance() will be called,
> on demand and which tries to fetch the resources (clocks, gpios etc).
> If any of those attempts fetching a resource fails, its corresponding
> error code should be propagated to the caller - including
> -EPROBE_DEFER.
> 
> Regarding the "always compile all pwrseq libraries"; no we don't need
> to do that. Instead we only need a to have a stub function for
> pwrseq_XX_alloc_instance, in case its corresponding Kconfig option is
> unset. That stub, should of course return an error code.
> 

I will have a updated version for your suggestion, thanks.

-- 

Best Regards,
Peter Chen