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

[Marek Szyprowski <m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>]

Hello,

On 2014-10-31 19:46, Paul Zimmerman wrote:
>> From: Marek Szyprowski [mailto:m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org]
>> 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-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
>> ---
>>   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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