Re: [PATCH v3 2/7] usb: misc: onboard_dev: add support for non-hub devices

From: Javier Carrasco <javier.carrasco@wolfvision.net>
To: Matthias Kaehlcke <mka@chromium.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>, Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-sound@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org
Subject: Re: [PATCH v3 2/7] usb: misc: onboard_dev: add support for non-hub devices
Date: Tue, 13 Feb 2024 11:00:43 +0100	[thread overview]
Message-ID: <2a23817d-b797-4659-a4e6-5c8a75864c90@wolfvision.net> (raw)
In-Reply-To: <ZcJ9OnYOtUVMu2Yk@google.com>

On 06.02.24 19:40, Matthias Kaehlcke wrote:
> On Tue, Feb 06, 2024 at 02:59:30PM +0100, Javier Carrasco wrote:
>> Most of the functionality this driver provides can be used by non-hub
>> devices as well.
>>
>> To account for the hub-specific code, add a flag to the device data
>> structure and check its value for hub-specific code.
>>
>> Signed-off-by: Javier Carrasco <javier.carrasco@wolfvision.net>
>> ---
>>  drivers/usb/misc/onboard_usb_dev.c |  3 +++
>>  drivers/usb/misc/onboard_usb_dev.h | 10 ++++++++++
>>  2 files changed, 13 insertions(+)
>>
>> diff --git a/drivers/usb/misc/onboard_usb_dev.c b/drivers/usb/misc/onboard_usb_dev.c
>> index e2e1e1e30c1e..3ac21ec38ac0 100644
>> --- a/drivers/usb/misc/onboard_usb_dev.c
>> +++ b/drivers/usb/misc/onboard_usb_dev.c
>> @@ -123,6 +123,9 @@ static int __maybe_unused onboard_dev_suspend(struct device *dev)
>>  	if (onboard_dev->always_powered_in_suspend)
>>  		return 0;
>>  
>> +	if (!onboard_dev->pdata->is_hub)
>> +		return onboard_dev_power_off(onboard_dev);
> 
> Why turn the device always off when it isn't a hub? It could be a device
> with wakeup support.
> 
> I really regret making 'off in suspend' the default :(
> 

The power management seems to be a critical point to consider.

Maybe we keep the current implementation and add support to non-hub
devices by simply adding a check to set power_off to false:

static int __maybe_unused onboard_dev_suspend(struct device *dev)

{

        struct onboard_dev *onboard_dev = dev_get_drvdata(dev);

        struct usbdev_node *node;

        bool power_off = true;

        if (onboard_dev->always_powered_in_suspend)

                return 0;

        mutex_lock(&onboard_dev->lock);

        list_for_each_entry(node, &onboard_dev->udev_list, list) {

                if (!device_may_wakeup(node->udev->bus->controller))

                        continue;

~                if (usb_wakeup_enabled_descendants(node->udev) ||

+                    !onboard_dev->pdata->is_hub) {

                        power_off = false;

                        break;

                }

        }

        mutex_unlock(&onboard_dev->lock);

        if (!power_off)

                return 0;

        return onboard_dev_power_off(onboard_dev);

}

Best regards,
Javier Carrasco