linux-kernel - Re: [PATCH v3 0/5] Add function suspend/resume and remote wakeup support

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Message-ID: <20230207012412.m2imw4bodu7ehvn4@synopsys.com>
Date:   Tue, 7 Feb 2023 01:24:21 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Elson Roy Serrao <quic_eserrao@...cinc.com>
CC:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        "balbi@...nel.org" <balbi@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "quic_wcheng@...cinc.com" <quic_wcheng@...cinc.com>,
        "quic_jackp@...cinc.com" <quic_jackp@...cinc.com>
Subject: Re: [PATCH v3 0/5] Add function suspend/resume and remote wakeup
 support

Hi Elson,

On Mon, Feb 06, 2023, Elson Roy Serrao wrote:
> Changes in v3
>  - Modified rw_capable flag to reflect the gadgets capability for wakeup
>    signalling.
>  - Added a check to configure wakeup bit in bmAttributes only if gadget
>    is capable of triggering wakeup.
>  - Implemented a gadget op for composite layer to inform UDC whether device
>    is configured for remote wakeup.
>  - Added a check in __usb_gadget_wakeup() API to trigger wakeup only if the
>    device is configured for it.
>  - Cosmetic changes in dwc3_gadget_func_wakeup() API.
> 
> Changes in v2
>  - Added a flag to indicate whether the device is remote wakeup capable.
>  - Added an async parameter to _dwc3_gadget_wakeup() API and few cosmetic
>    changes.
>  - Added flags to reflect the state of  function suspend and function remote
>    wakeup to usb_function struct rather than function specific struct (f_ecm).
>  - Changed the dwc3_gadget_func__wakeup() API to run synchronously by first
>    checking the link state and then sending the device notification. Also
>    added debug log for DEVICE_NOTIFICATION generic cmd.
>  - Added changes to arm the device for remotewakeup/function remotewakeup
>    only if device is capable.
> 
> An usb device can initate a remote wakeup and bring the link out of
> suspend as dictated by the DEVICE_REMOTE_WAKEUP feature selector.
> To achieve this an interface can invoke gadget_wakeup op and wait for the
> device to come out of LPM. But the current polling based implementation
> fails if the host takes a long time to drive the resume signaling specially
> in high speed capable devices. Switching to an interrupt based approach is
> more robust and efficient. This can be leveraged by enabling link status
> change events and triggering a gadget resume when the link comes to active
> state.
> 
> If the device is enhanced super-speed capable, individual interfaces can
> also be put into suspend state. An interface can be in function suspend
> state even when the device is not in suspend state. Function suspend state
> is retained throughout the device suspend entry and exit process.
> A function can be put to function suspend through FUNCTION_SUSPEND feature
> selector sent by the host. This setup packet also decides whether that
> function is capable of initiating a function remote wakeup. When the
> function sends a wakeup notification to the host the link must be first
> brought to a non-U0 state and then this notification is sent.
> 
> This change adds the infrastructure needed to support the above
> functionalities.
> 
> Elson Roy Serrao (5):
>   usb: gadget: Properly configure the device for remote wakeup
>   usb: dwc3: Add remote wakeup handling
>   usb: gadget: Add function wakeup support
>   usb: dwc3: Add function suspend and function wakeup support
>   usb: gadget: f_ecm: Add suspend/resume and remote wakeup support
> 
>  drivers/usb/dwc3/core.h               |   5 ++
>  drivers/usb/dwc3/debug.h              |   2 +
>  drivers/usb/dwc3/ep0.c                |  16 ++---
>  drivers/usb/dwc3/gadget.c             | 110 +++++++++++++++++++++++++++++++---
>  drivers/usb/gadget/composite.c        |  50 +++++++++++++++-
>  drivers/usb/gadget/function/f_ecm.c   |  68 +++++++++++++++++++++
>  drivers/usb/gadget/function/u_ether.c |  63 +++++++++++++++++++
>  drivers/usb/gadget/function/u_ether.h |   4 ++
>  drivers/usb/gadget/udc/core.c         |  46 ++++++++++++++
>  drivers/usb/gadget/udc/trace.h        |   5 ++
>  include/linux/usb/composite.h         |   6 ++
>  include/linux/usb/gadget.h            |  12 ++++
>  12 files changed, 371 insertions(+), 16 deletions(-)
> 
> -- 
> 2.7.4
> 

Hi Elson,

Thanks for your patches! I provided some comments. Hopefully they can be
merged soon.

Thanks,
Thinh