Re: [PATCH v4 7/9] usb: misc: qcom_eud: fix virtual attach/detach event handling

[Peter Chen <peter.chen@kernel.org>]

On 26-05-01 10:06:33, Elson Serrao wrote:
> EUD provides virtual USB attach/detach events to simulate cable
> plug/unplug while maintaining the physical debug connection. However,
> the current implementation incorrectly sets the USB role to HOST on
> virtual detach, which doesn't represent the disconnected state.
> 
> Fix the virtual detach handling by setting the USB role to NONE
> instead of HOST, correctly representing the disconnected state.
> 
> Signed-off-by: Elson Serrao <elson.serrao@oss.qualcomm.com>
> Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Reviewed-by: Peter Chen <peter.chen@kernel.org>

Peter
> ---
>  drivers/usb/misc/qcom_eud.c | 18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/misc/qcom_eud.c b/drivers/usb/misc/qcom_eud.c
> index 4734b6307a85..187cbffbab13 100644
> --- a/drivers/usb/misc/qcom_eud.c
> +++ b/drivers/usb/misc/qcom_eud.c
> @@ -320,10 +320,26 @@ static irqreturn_t handle_eud_irq_thread(int irq, void *data)
>  
>  	path = chip->paths[chip->port_idx];
>  
> +	/*
> +	 * EUD virtual attach/detach event handling for low power debugging:
> +	 *
> +	 * When EUD is enabled in debug mode, the device remains physically
> +	 * connected to the PC throughout the debug session, keeping the USB
> +	 * controller active. This prevents testing of low power scenarios that
> +	 * require USB disconnection.
> +	 *
> +	 * EUD solves this by providing virtual USB attach/detach events while
> +	 * maintaining the physical connection. These events are triggered from
> +	 * the Host PC via the enumerated EUD control interface and delivered
> +	 * to the EUD driver as interrupts.
> +	 *
> +	 * These notifications are forwarded to the USB controller through role
> +	 * switch framework.
> +	 */
>  	if (chip->usb_attached)
>  		ret = usb_role_switch_set_role(path->controller_sw, USB_ROLE_DEVICE);
>  	else
> -		ret = usb_role_switch_set_role(path->controller_sw, USB_ROLE_HOST);
> +		ret = usb_role_switch_set_role(path->controller_sw, USB_ROLE_NONE);
>  	if (ret)
>  		dev_err(chip->dev, "failed to set role switch\n");
>  
> -- 
> 2.34.1
> 
> 

-- 

Thanks,
Peter Chen