Re: [PATCH v3 1/2] usb: dwc2/gadget: add mutex to serialize init/deinit calls

[Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>]

Hello,

On 2014-10-31 19:46, Paul Zimmerman wrote:
> > From: Marek Szyprowski [mailto:m.szyprowski@xxxxxxxxxxx]
> > 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.szyprowski@xxxxxxxxxxx>
> > ---
> >   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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