linux-kernel - Re: [PATCH] usb: dwc3: core: Disable USB2.0 phy suspend when dwc3 acts as host role

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Date:   Tue, 15 Nov 2016 12:49:53 +0200
From:   Felipe Balbi <balbi@...nel.org>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     gregkh@...uxfoundation.org, broonie@...nel.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        baolin.wang@...aro.org
Subject: Re: [PATCH] usb: dwc3: core: Disable USB2.0 phy suspend when dwc3 acts as host role


Hi,

Baolin Wang <baolin.wang@...aro.org> writes:
> When dwc3 controller acts as host role with attaching slow speed device
> (like mouse or keypad). Then if we plugged out the slow speed device,
> it will timeout to run the deconfiguration endpoint command to drop the
> endpoint's resources. Some xHCI command timeout log as below when
> disconnecting one slow device:
>
> [   99.807739] c0 xhci-hcd.0.auto: Port Status Change Event for port 1
> [   99.814699] c0 xhci-hcd.0.auto: resume root hub
> [   99.819992] c0 xhci-hcd.0.auto: handle_port_status: starting port
> 				   polling.
> [   99.827808] c0 xhci-hcd.0.auto: get port status, actual port 0 status
> 				   = 0x202a0
> [   99.835903] c0 xhci-hcd.0.auto: Get port status returned 0x10100
> [   99.850052] c0 xhci-hcd.0.auto: clear port connect change, actual
> 				   port 0 status  = 0x2a0
> [   99.859313] c0 xhci-hcd.0.auto: Cancel URB ffffffc01ed6cd00, dev 1,
> 				   ep 0x81, starting at offset 0xc406d210
> [   99.869645] c0 xhci-hcd.0.auto: // Ding dong!
> [   99.874776] c0 xhci-hcd.0.auto: Stopped on Transfer TRB
> [   99.880713] c0 xhci-hcd.0.auto: Removing canceled TD starting at
> 				   0xc406d210 (dma).
> [   99.889012] c0 xhci-hcd.0.auto: Finding endpoint context
> [   99.895069] c0 xhci-hcd.0.auto: Cycle state = 0x1
> [   99.900519] c0 xhci-hcd.0.auto: New dequeue segment =
> 				   ffffffc1112f0880 (virtual)
> [   99.908655] c0 xhci-hcd.0.auto: New dequeue pointer = 0xc406d220 (DMA)
> [   99.915927] c0 xhci-hcd.0.auto: Set TR Deq Ptr cmd, new deq seg =
> 				   ffffffc1112f0880 (0xc406d000 dma),
> 				   new deq ptr = ffffff8002175220
> 				   (0xc406d220 dma), new cycle = 1
> [   99.931242] c0 xhci-hcd.0.auto: // Ding dong!
> [   99.936360] c0 xhci-hcd.0.auto: Successful Set TR Deq Ptr cmd,
> 				   deq = @c406d220
> [   99.944458] c0 xhci-hcd.0.auto: xhci_hub_status_data: stopping port
> 				   polling.
> [  100.047619] c0 xhci-hcd.0.auto: xhci_drop_endpoint called for udev
> 				   ffffffc01ae08800
> [  100.057002] c0 xhci-hcd.0.auto: drop ep 0x81, slot id 1, new drop
> 				   flags = 0x8, new add flags = 0x0
> [  100.067878] c0 xhci-hcd.0.auto: xhci_check_bandwidth called for udev
> 				   ffffffc01ae08800
> [  100.076868] c0 xhci-hcd.0.auto: New Input Control Context:
>
> ......
>
> [  100.427252] c0 xhci-hcd.0.auto: // Ding dong!
> [  105.430728] c0 xhci-hcd.0.auto: Command timeout
> [  105.436029] c0 xhci-hcd.0.auto: Abort command ring
> [  113.558223] c0 xhci-hcd.0.auto: Command completion event does not match
> 				   command
> [  113.569778] c0 xhci-hcd.0.auto: Timeout while waiting for configure
> 				   endpoint command
>
> The reason is it will suspend USB phy to disable phy clock when
> disconnecting the slow USB decice, that will hang on the xHCI commands
> executing which depends on the phy clock.
>
> Thus we should disable USB2.0 phy suspend feature when dwc3 acts as host
> role.
>
> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
> ---
>  drivers/usb/dwc3/core.c |   14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 9a4a5e4..0b646cf 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -565,6 +565,20 @@ static int dwc3_phy_setup(struct dwc3 *dwc)
>  	if (dwc->revision > DWC3_REVISION_194A)
>  		reg |= DWC3_GUSB2PHYCFG_SUSPHY;
>  
> +	/*
> +	 * When dwc3 controller acts as host role with attaching one slow speed
> +	 * device (like mouse or keypad). Then if we plugged out the slow speed
> +	 * device, it will timeout to run the deconfiguration endpoint command.
> +	 * The reason is it will suspend USB phy to disable phy clock when
> +	 * disconnecting slow speed decice, which will affect the xHCI commands
> +	 * executing.
> +	 *
> +	 * Thus we should disable USB 2.0 phy suspend feature when dwc3 acts as
> +	 * host role.
> +	 */
> +	if (dwc->dr_mode == USB_DR_MODE_HOST || dwc->dr_mode == USB_DR_MODE_OTG)
> +		reg &= ~DWC3_GUSB2PHYCFG_SUSPHY;

which version of the core you're using? Recent version (since 1.94A,
IIRC) can manage core suspend automatically. Also, this patch of yours
will cause a power consumption regression.

-- 
balbi

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