Hello,

On 2014-10-31 19:46, Paul Zimmerman wrote:
From: Marek Szyprowski [mailto:m.szyprow...@samsung.com]
Sent: Friday, October 31, 2014 3:13 AM

This patch adds mutex, which protects initialization and
deinitialization procedures against suspend/resume methods.

Signed-off-by: Marek Szyprowski <m.szyprow...@samsung.com>
---
  drivers/usb/dwc2/core.h   |  1 +
  drivers/usb/dwc2/gadget.c | 20 ++++++++++++++++++++
  2 files changed, 21 insertions(+)

diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index 9f77b4d1c5ff..58732a9a0019 100644
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -187,6 +187,7 @@ struct s3c_hsotg {
        struct s3c_hsotg_plat    *plat;

        spinlock_t              lock;
+       struct mutex            init_mutex;

        void __iomem            *regs;
        int                     irq;
diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index d8dda39c9e16..a2e4272a904e 100644
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -21,6 +21,7 @@
  #include <linux/platform_device.h>
  #include <linux/dma-mapping.h>
  #include <linux/debugfs.h>
+#include <linux/mutex.h>
  #include <linux/seq_file.h>
  #include <linux/delay.h>
  #include <linux/io.h>
@@ -2908,6 +2909,7 @@ static int s3c_hsotg_udc_start(struct usb_gadget *gadget,
                return -EINVAL;
        }

+       mutex_lock(&hsotg->init_mutex);
        WARN_ON(hsotg->driver);

        driver->driver.bus = NULL;
@@ -2933,9 +2935,12 @@ static int s3c_hsotg_udc_start(struct usb_gadget *gadget,

        dev_info(hsotg->dev, "bound driver %s\n", driver->driver.name);

+       mutex_unlock(&hsotg->init_mutex);
+
        return 0;

  err:
+       mutex_unlock(&hsotg->init_mutex);
        hsotg->driver = NULL;
        return ret;
  }
@@ -2957,6 +2962,8 @@ static int s3c_hsotg_udc_stop(struct usb_gadget *gadget,
        if (!hsotg)
                return -ENODEV;

+       mutex_lock(&hsotg->init_mutex);
+
        /* all endpoints should be shutdown */
        for (ep = 1; ep < hsotg->num_of_eps; ep++)
                s3c_hsotg_ep_disable(&hsotg->eps[ep].ep);
@@ -2974,6 +2981,8 @@ static int s3c_hsotg_udc_stop(struct usb_gadget *gadget,

        clk_disable(hsotg->clk);

+       mutex_unlock(&hsotg->init_mutex);
+
        return 0;
  }

@@ -3002,6 +3011,7 @@ static int s3c_hsotg_pullup(struct usb_gadget *gadget, 
int is_on)

        dev_dbg(hsotg->dev, "%s: is_on: %d\n", __func__, is_on);

+       mutex_lock(&hsotg->init_mutex);
        spin_lock_irqsave(&hsotg->lock, flags);
        if (is_on) {
                clk_enable(hsotg->clk);
@@ -3013,6 +3023,7 @@ static int s3c_hsotg_pullup(struct usb_gadget *gadget, 
int is_on)

        hsotg->gadget.speed = USB_SPEED_UNKNOWN;
        spin_unlock_irqrestore(&hsotg->lock, flags);
+       mutex_unlock(&hsotg->init_mutex);

        return 0;
  }
@@ -3507,6 +3518,7 @@ static int s3c_hsotg_probe(struct platform_device *pdev)
        }

        spin_lock_init(&hsotg->lock);
+       mutex_init(&hsotg->init_mutex);

        hsotg->irq = ret;

@@ -3652,6 +3664,8 @@ static int s3c_hsotg_suspend(struct platform_device 
*pdev, pm_message_t state)
        unsigned long flags;
        int ret = 0;

+       mutex_lock(&hsotg->init_mutex);
+
        if (hsotg->driver)
                dev_info(hsotg->dev, "suspending usb gadget %s\n",
                         hsotg->driver->driver.name);
@@ -3674,6 +3688,8 @@ static int s3c_hsotg_suspend(struct platform_device 
*pdev, pm_message_t state)
                clk_disable(hsotg->clk);
        }

+       mutex_unlock(&hsotg->init_mutex);
+
        return ret;
  }

@@ -3683,7 +3699,9 @@ static int s3c_hsotg_resume(struct platform_device *pdev)
        unsigned long flags;
        int ret = 0;

+       mutex_lock(&hsotg->init_mutex);
        if (hsotg->driver) {
+
                dev_info(hsotg->dev, "resuming usb gadget %s\n",
                         hsotg->driver->driver.name);

@@ -3699,6 +3717,8 @@ static int s3c_hsotg_resume(struct platform_device *pdev)
        s3c_hsotg_core_connect(hsotg);
        spin_unlock_irqrestore(&hsotg->lock, flags);

+       mutex_unlock(&hsotg->init_mutex);
+
        return ret;
  }

Hmm. I can't find any other UDC driver that uses a mutex in its
suspend/resume functions. Can you explain why this is needed only
for dwc2?

I've posted this version because I thought you were not convinced that the patch "usb: dwc2/gadget: rework suspend/resume code to correctly restore gadget state" can add code for initialization and deinitialization in suspend/resume paths.

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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