[PATCH v1] usb: dwc3: core: Fix timeout check

[Marek Vasut]

On 1/13/25 7:38 AM, Varadarajan Narayanan wrote:
> On Sun, Jan 12, 2025 at 09:48:41PM +0100, Marek Vasut wrote:
>> On 1/10/25 8:43 AM, Varadarajan Narayanan wrote:
>>> dwc3_core_init loops 'timeout' times to check if the IP block is out
>>> of reset using 'while (timeout--)'. If there is some issue and
>>> the block doesn't come out of reset, the loop will run till
>>> 'timeout' becomes zero and the post decrement operator would set
>>> timeout to 0xffffffff. Though the IP block is not out reset, the
>>> subsequent if check 'if !timeout' would fail as timeout is not
>>> equal to zero and the function proceeds with the initialization.
>>>
>>> Make this a pre decrement to address this.
>>>
>>> Signed-off-by: Varadarajan Narayanan <quic_varada at quicinc.com>
>> Does the following patch work too ? It removes all the fragile open-coded
>> polling
>>
>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>> index a35b8c2f646..7e7017d4be7 100644
>> --- a/drivers/usb/dwc3/core.c
>> +++ b/drivers/usb/dwc3/core.c
>> @@ -29,6 +29,7 @@
>>   #include <linux/usb/ch9.h>
>>   #include <linux/usb/gadget.h>
>>   #include <linux/bitfield.h>
>> +#include <linux/iopoll.h>
>>   #include <linux/math64.h>
>>   #include <linux/time.h>
>>
>> @@ -587,7 +588,6 @@ static void dwc3_set_incr_burst_type(struct dwc3 *dwc)
>>    */
>>   static int dwc3_core_init(struct dwc3 *dwc)
>>   {
>> -	unsigned long		timeout;
>>   	u32			hwparams4 = dwc->hwparams.hwparams4;
>>   	u32			reg;
>>   	int			ret;
>> @@ -610,17 +610,12 @@ static int dwc3_core_init(struct dwc3 *dwc)
>>   	}
>>
>>   	/* issue device SoftReset too */
>> -	timeout = 5000;
>>   	dwc3_writel(dwc->regs, DWC3_DCTL, DWC3_DCTL_CSFTRST);
>> -	while (timeout--) {
>> -		reg = dwc3_readl(dwc->regs, DWC3_DCTL);
>> -		if (!(reg & DWC3_DCTL_CSFTRST))
>> -			break;
>> -	};
>> -
>> -	if (!timeout) {
>> +	ret = read_poll_timeout(dwc3_readl, reg,
>> +				!(reg & DWC3_DCTL_CSFTRST),
>> +				1, 5000, dwc->regs, DWC3_DCTL);
>> +	if (ret) {
>>   		dev_err(dwc->dev, "Reset Timed Out\n");
>> -		ret = -ETIMEDOUT;
>>   		goto err0;
>>   	}
> 
> This worked too.
> 
> Tested-By: Varadarajan Narayanan <quic_varada at quicinc.com>
Please send a V2 patch like that , including the TB , thanks !