linux-kernel - Re: [PATCH v3 2/3] usb: xhci: implement device_suspend/device

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Date:	Fri, 08 May 2015 09:23:40 +0800
From:	"Lu, Baolu" <baolu.lu@...ux.intel.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:	Mathias Nyman <mathias.nyman@...el.com>,
	Alan Stern <stern@...land.harvard.edu>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/3] usb: xhci: implement device_suspend/device_resume
 entries



On 05/08/2015 04:47 AM, Greg Kroah-Hartman wrote:
> On Thu, May 07, 2015 at 10:18:15AM +0800, Lu Baolu wrote:
>> This patch implements device_suspend/device_resume entries for xHC driver.
>> device_suspend will be called when a USB device is about to suspend. It
>> will issue a stop endpoint command for each endpoint in this device. The
>> Suspend(SP) bit in the command TRB will set which will give xHC a hint
>> about the suspend. device_resume will be called when a USB device is just
>> resumed. It will ring doorbells of all endpoint unconditionally. XHC may
>> use these suspend/resume hints to optimize its operation.
>>
>> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
>> ---
>>   drivers/usb/host/xhci-hub.c |  2 +-
>>   drivers/usb/host/xhci.c     | 40 ++++++++++++++++++++++++++++++++++++++++
>>   drivers/usb/host/xhci.h     | 11 +++++++++++
>>   3 files changed, 52 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
>> index 0827d7c..a83e82e 100644
>> --- a/drivers/usb/host/xhci-hub.c
>> +++ b/drivers/usb/host/xhci-hub.c
>> @@ -266,7 +266,7 @@ int xhci_find_slot_id_by_port(struct usb_hcd *hcd, struct xhci_hcd *xhci,
>>    * to complete.
>>    * suspend will set to 1, if suspend bit need to set in command.
>>    */
>> -static int xhci_stop_device(struct xhci_hcd *xhci, int slot_id, int suspend)
>> +int xhci_stop_device(struct xhci_hcd *xhci, int slot_id, int suspend)
>>   {
>>   	struct xhci_virt_device *virt_dev;
>>   	struct xhci_command *cmd;
>> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
>> index ec8ac16..6b61833 100644
>> --- a/drivers/usb/host/xhci.c
>> +++ b/drivers/usb/host/xhci.c
>> @@ -4680,6 +4680,40 @@ int xhci_disable_usb3_lpm_timeout(struct usb_hcd *hcd,
>>   		return ret;
>>   	return 0;
>>   }
>> +
>> +/*
>> + * xHCI compatible host controller driver expects to be notified prior to
>> + * selectively suspending a device. xHCI hcd could optimize the endpoint
>> + * cache for power saving purpose. Refer to 4.15.1.1 of xHCI 1.1.
>> + */
>> +void xhci_device_suspend(struct usb_hcd *hcd,
>> +			struct usb_device *udev, pm_message_t msg)
> You never use the 'msg' field, so please remove it from the callback.

'msg' could be used in another patch to determine the pm event types:
auto-suspend or system suspend. I didn't bring up that patch together
with this patch series because 1) that's part of xhci 1.1 features, and
2) it's still not tested yet.

>
>> +{
>> +	struct xhci_hcd	*xhci;
>> +
>> +	xhci = hcd_to_xhci(hcd);
>> +	if (!xhci || !xhci->devs[udev->slot_id])
>> +		return;
>> +
>> +	xhci_stop_device(xhci, udev->slot_id, 1);
>> +}
>> +
>> +/*
>> + * xHCI compatible host controller driver expects to be notified after a
>> + * USB device is resumed. xHCI hcd could optimize the endpoint cache
>> + * to reduce the latency. Refer to 4.15.1.1 of xHCI 1.1.
>> + */
>> +void xhci_device_resume(struct usb_hcd *hcd,
>> +			struct usb_device *udev, pm_message_t msg)
> Same here.

I will remove 'msg' field in this call back. I don't see any cases where
msg could be used.

Thank you,
Baolu

>
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