linux-kernel - Re: [PATCH RESEND] usb: dwc2: avoid leaking DMA channels on disconnection

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Date:	Mon, 16 Mar 2015 19:06:19 -0700
From:	John Youn <John.Youn@...opsys.com>
To:	Yunzhi Li <lyz@...k-chips.com>,
	Vincent Palatin <vpalatin@...omium.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"balbi@...com" <balbi@...com>
CC:	Doug Anderson <dianders@...omium.org>,
	Julius Werner <jwerner@...gle.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	John Youn <John.Youn@...opsys.com>
Subject: Re: [PATCH RESEND] usb: dwc2: avoid leaking DMA channels on disconnection

On 3/16/2015 2:50 AM, Yunzhi Li wrote:
> Hi
>> When the HCD is disconnected, the DMA transfers still in-flight were cleaned-up
>> but the count of available DMA channels (e.g. available_host_channels) was not
>> reset.
>> The pool of DMA channels can be depleted when doing unclean
>> disconnection of USB peripherals, and reaches the point where no
>> transfer was possible until the next reboot/reload of the driver.
>>
>> Tested by putting a programmable USB mux on the port and randomly
>> plugging/unpluging a USB HUB with USB mass-storage key, USB-audio and
>> USB-ethernet dongle connected to its downstream ports, and also doing the
>> disconnection early while the devices are still enumerating to get more URBs
>> in-flight.
>> After the patch, the devices are still enumerating after thousands of cycles,
>> while the port was totally dead before.
>>
>> Signed-off-by: Vincent Palatin <vpalatin@...omium.org>
>> ---
>> I'm re-sending it, it seems the previous email did not show up.
>>
>>   drivers/usb/dwc2/hcd.c | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
>> index c78c874..559b55e 100644
>> --- a/drivers/usb/dwc2/hcd.c
>> +++ b/drivers/usb/dwc2/hcd.c
>> @@ -257,6 +257,14 @@ static void dwc2_hcd_cleanup_channels(struct dwc2_hsotg *hsotg)
>>   		 */
>>   		channel->qh = NULL;
>>   	}
>> +	/* All channels have been freed, mark them available */
>> +	if (hsotg->core_params->uframe_sched > 0) {
>> +		hsotg->available_host_channels =
>> +			hsotg->core_params->host_channels;
>> +	} else {
>> +		hsotg->non_periodic_channels = 0;
>> +		hsotg->periodic_channels = 0;
>> +	}
>>   }
>>   
>>   /**
> 
> I have reviewed this patch. Obviously,it makes sense.
> 
> Reviewed-by: Yunzhi Li <lyz@...k-chips.com>


Acked-by: John Youn <johnyoun@...opsys.com>



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