Re: [PATCH v6 4/8] usb: core: add power sequence handling for USB devices

[Peter Chen]

On Thu, Sep 01, 2016 at 01:32:49PM +0530, Vaibhav Hiremath wrote:
> 
> 
> On Monday 15 August 2016 02:43 PM, Peter Chen wrote:
> >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. At first, it calls pwrseq_alloc_generic
> >to create a generic power sequence instance, then 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@xxxxxxx>
> >Tested-by Joshua Clayton <stillcompiling@xxxxxxxxx>
> >---
> >  drivers/usb/core/Makefile |   1 +
> >  drivers/usb/core/hub.c    |  12 ++++--
> >  drivers/usb/core/hub.h    |  12 ++++++
> >  drivers/usb/core/pwrseq.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 122 insertions(+), 3 deletions(-)
> >  create mode 100644 drivers/usb/core/pwrseq.c
> >
> >diff --git a/drivers/usb/core/Makefile b/drivers/usb/core/Makefile
> >index 9780877..39f2149 100644
> >--- a/drivers/usb/core/Makefile
> >+++ b/drivers/usb/core/Makefile
> >@@ -9,5 +9,6 @@ usbcore-y += port.o of.o
> >  usbcore-$(CONFIG_PCI)		+= hcd-pci.o
> >  usbcore-$(CONFIG_ACPI)		+= usb-acpi.o
> >+usbcore-$(CONFIG_PWRSEQ_GENERIC) += pwrseq.o
> >  obj-$(CONFIG_USB)		+= usbcore.o
> >diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> >index bee1351..a346a8b 100644
> >--- a/drivers/usb/core/hub.c
> >+++ b/drivers/usb/core/hub.c
> >@@ -1700,6 +1700,7 @@ static void hub_disconnect(struct usb_interface *intf)
> >  	hub->error = 0;
> >  	hub_quiesce(hub, HUB_DISCONNECT);
> >+	hub_pwrseq_off(hub);
> >  	mutex_lock(&usb_port_peer_mutex);
> >  	/* Avoid races with recursively_mark_NOTATTACHED() */
> >@@ -1733,6 +1734,7 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
> >  	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);
> >@@ -1839,6 +1841,7 @@ descriptor_error:
> >  	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_on_list);
> >  	usb_get_intf(intf);
> >  	usb_get_dev(hdev);
> >@@ -1852,11 +1855,14 @@ descriptor_error:
> >  	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_pwrseq_on(hub);
> >+		if (!ret)
> >+			return 0;
> >+	}
> >  	hub_disconnect(intf);
> >-	return -ENODEV;
> >+	return ret;
> >  }
> >  static int
> >diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
> >index 34c1a7e..9473f6f 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_on_list; /* powered pwrseq node list */
> >  };
> >  /**
> >@@ -166,3 +167,14 @@ static inline int hub_port_debounce_be_stable(struct usb_hub *hub,
> >  {
> >  	return hub_port_debounce(hub, port1, false);
> >  }
> >+
> >+#if IS_ENABLED(CONFIG_PWRSEQ_GENERIC)
> >+int hub_pwrseq_on(struct usb_hub *hub);
> >+void hub_pwrseq_off(struct usb_hub *hub);
> >+#else
> >+static inline int hub_pwrseq_on(struct usb_hub *hub)
> >+{
> >+	return 0;
> >+}
> >+static inline void hub_pwrseq_off(struct usb_hub *hub) {}
> >+#endif /* CONFIG_PWRSEQ_GENERIC */
> >diff --git a/drivers/usb/core/pwrseq.c b/drivers/usb/core/pwrseq.c
> >new file mode 100644
> >index 0000000..837fe66
> >--- /dev/null
> >+++ b/drivers/usb/core/pwrseq.c
> >@@ -0,0 +1,100 @@
> >+/*
> >+ * pwrseq.c	USB device power sequence management
> >+ *
> >+ * Copyright (C) 2016 Freescale Semiconductor, Inc.
> >+ * Author: Peter Chen <peter.chen@xxxxxxx>
> >+ *
> >+ * 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.  If not, see <http://www.gnu.org/licenses/>.
> >+ */
> >+
> >+#include <linux/list.h>
> >+#include <linux/of.h>
> >+#include <linux/power/pwrseq.h>
> >+#include <linux/slab.h>
> >+#include <linux/usb.h>
> >+#include <linux/usb/hcd.h>
> >+
> >+#include "hub.h"
> >+
> >+struct usb_pwrseq_node {
> >+	struct pwrseq *pwrseq;
> >+	struct list_head list;
> >+};
> >+
> >+static int hub_of_pwrseq_on(struct device_node *np, struct usb_hub *hub)
> >+{
> >+	struct pwrseq *pwrseq;
> >+	struct usb_pwrseq_node *pwrseq_node;
> >+	int ret;
> >+
> >+	pwrseq = pwrseq_alloc_generic();
> >+	if (IS_ERR(pwrseq))
> >+		return PTR_ERR(pwrseq);
> >+
> >+	ret = pwrseq_get(np, pwrseq);
> >+	if (ret)
> >+		goto pwr_free;
> >+
> >+	ret = pwrseq_on(np, pwrseq);
> >+	if (ret)
> >+		goto pwr_put;
> >+
> >+	pwrseq_node = kzalloc(sizeof(*pwrseq_node), GFP_KERNEL);
> 
> You probably want to check the return value here.
> 
> I think someone already commented on this, but still for the record
> providing it.
> 

Thanks, I will.

-- 

Best Regards,
Peter Chen