Date:   Wed, 25 Nov 2020 11:52:31 +0200
From:   Roger Quadros <rogerq@...com>
To:     Peter Chen <peter.chen@....com>,
        "pawell@...ence.com" <pawell@...ence.com>
CC:     "heikki.krogerus@...ux.intel.com" <heikki.krogerus@...ux.intel.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "balbi@...nel.org" <balbi@...nel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Revert "usb: cdns3: core: quit if it uses role switch
 class"



On 25/11/2020 02:36, Peter Chen wrote:
> On 20-11-24 14:22:25, Roger Quadros wrote:
>> Peter,
>>
>> On 24/11/2020 13:47, Peter Chen wrote:
>>> On 20-11-24 12:33:34, Roger Quadros wrote:
>>>>>>>
>>>>>>> I am sorry about that. Do you use role switch /sys entry, if you have
>>>>>>> used, I prefer using "usb-role-switch" property at dts to judge if SoC
>>>>>>> OTG signals or external signals for role switch. If you have not used
>>>>>>> it, I prefer only setting cdns->role_sw for role switch use cases.
>>>>>>>
>>>>>>
>>>>>> We use both hardware role switch and /sys entries for manually forcing a
>>>>>> certain role.
>>>>>>
>>>>>> We do not set any "usb-role-switch" property at DTS.
>>>>>>
>>>>>> Currently cdns->role_sw is being always set by driver irrespective of any DT
>>>>>> property, so this patch is clearly wrong and needs to be reverted.
>>>>>>
>>>>>> What do you think?
>>>>>>
>>>>>
>>>>> Could you accept below fix?
>>>>>
>>>>> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
>>>>> index 2e469139769f..fdd52e87a7b2 100644
>>>>> --- a/drivers/usb/cdns3/core.c
>>>>> +++ b/drivers/usb/cdns3/core.c
>>>>> @@ -280,8 +280,8 @@ int cdns3_hw_role_switch(struct cdns3 *cdns)
>>>>>            enum usb_role real_role, current_role;
>>>>>            int ret = 0;
>>>>>
>>>>> -       /* Depends on role switch class */
>>>>> -       if (cdns->role_sw)
>>>>> +       /* quit if switch role through external signals */
>>>>> +       if (device_property_read_bool(cdns->dev, "usb-role-switch"))
>>>>>                    return 0;
>>>>>
>>>>>            pm_runtime_get_sync(cdns->dev);
>>>>
>>>> Although this will fix the issue I don't think this is making the driver to behave
>>>> as expected with usb-role-switch property.
>>>>
>>>> Now, even if usb-role-switch property is not present the driver will still register
>>>> the role switch driver.
>>>>
>>>> I think we need to register the role switch driver only if usb-role-switch property
>>>> is present. We would also need to set the default role if role-switch-default-mode is present.
>>>>
>>>> How about the following? It still doesn't handle role-switch-default-mode property though.
>>>>
>>>
>>> Roger, you said you also use /sys entries (I suppose it means through role
>>> switch class) to do role switch, with your change, there will be no /sys
>>> entry for role switch.
>>
>> Sorry for the confusion. Although we do need both features (SW role switch + HW role switch)
>> I don't think it is required to operate simultaneously. If users need SW control they can set the DT flag.
>>
> 
> I see. I prefer embracing all things related to role switch under the
> firmware entry condition. Besides, I find another issue that devm_request_irq
> for wakeup_irq does not call usb_role_switch_unregister if it has
> failed. So, probably, two patches are needed. I am OK you send the
> patches to fix both.

Pawel, can you please confirm that if you are ok with either h/w role switching
or s/w role switching but not both working at the same time?

It would have been nice by user to to know the current role even for h/w based
swithcing but it looks like now that won't be possible.

cheers,
-roger
> 
> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
> index 2e469139769f..fc6a8152406c 100644
> --- a/drivers/usb/cdns3/core.c
> +++ b/drivers/usb/cdns3/core.c
> @@ -427,7 +427,6 @@ static irqreturn_t cdns3_wakeup_irq(int irq, void *data)
>    */
>   static int cdns3_probe(struct platform_device *pdev)
>   {
> -	struct usb_role_switch_desc sw_desc = { };
>   	struct device *dev = &pdev->dev;
>   	struct resource	*res;
>   	struct cdns3 *cdns;
> @@ -529,18 +528,21 @@ static int cdns3_probe(struct platform_device *pdev)
>   	if (ret)
>   		goto err2;
>   
> -	sw_desc.set = cdns3_role_set;
> -	sw_desc.get = cdns3_role_get;
> -	sw_desc.allow_userspace_control = true;
> -	sw_desc.driver_data = cdns;
> -	if (device_property_read_bool(dev, "usb-role-switch"))
> +	if (device_property_read_bool(dev, "usb-role-switch")) {
> +		struct usb_role_switch_desc sw_desc = { };
> +
> +		sw_desc.set = cdns3_role_set;
> +		sw_desc.get = cdns3_role_get;
> +		sw_desc.allow_userspace_control = true;
> +		sw_desc.driver_data = cdns;
>   		sw_desc.fwnode = dev->fwnode;
>   
> -	cdns->role_sw = usb_role_switch_register(dev, &sw_desc);
> -	if (IS_ERR(cdns->role_sw)) {
> -		ret = PTR_ERR(cdns->role_sw);
> -		dev_warn(dev, "Unable to register Role Switch\n");
> -		goto err3;
> +		cdns->role_sw = usb_role_switch_register(dev, &sw_desc);
> +		if (IS_ERR(cdns->role_sw)) {
> +			ret = PTR_ERR(cdns->role_sw);
> +			dev_warn(dev, "Unable to register Role Switch\n");
> +			goto err3;
> +		}
>   	}
>   
>   	if (cdns->wakeup_irq) {
> @@ -583,7 +585,8 @@ static int cdns3_probe(struct platform_device *pdev)
>   	return 0;
>   err4:
>   	cdns3_drd_exit(cdns);
> -	usb_role_switch_unregister(cdns->role_sw);
> +	if (cdns->role_sw)
> +		usb_role_switch_unregister(cdns->role_sw);
>   err3:
>   	set_phy_power_off(cdns);
>   err2:
> 

-- 
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

Powered by blists - more mailing lists