[PATCH v2 2/2] net: flexcan: add transceiver switch gpios support

[Marc Kleine-Budde]

On 06/28/2012 02:18 PM, Dong Aisheng wrote:
> On Thu, Jun 28, 2012 at 08:05:14PM +0800, Marc Kleine-Budde wrote:
>> On 06/28/2012 01:46 PM, Shawn Guo wrote:
>>> On Thu, Jun 28, 2012 at 07:33:28PM +0800, Dong Aisheng wrote:
>>>>> +		phy_stby_gpio = of_get_named_gpio_flags(pdev->dev.of_node,
>>>>> +							"phy-standby-gpios",
>>>>> +							0, &flags);
>>>>> +		if (gpio_is_valid(phy_stby_gpio)) {
>>>>> +			if (flags == OF_GPIO_ACTIVE_LOW)
>>>>> +				phy_stby_high = false;
>>>>> +			err = devm_gpio_request_one(&pdev->dev, phy_stby_gpio,
>>>>> +						    GPIOF_DIR_OUT,
>>>>> +						    "phy-standby");
>>>>> +			if (err) {
>>>>> +				dev_err(&pdev->dev,
>>>>> +					"failed to request gpio %d: %d\n",
>>>>> +					phy_stby_gpio, err);
>>>>> +				goto failed_gpio;
>>>> I checked mx28 evk, it seems the phy only has a STB gpio and shared by both CAN0&CAN1.
>>>> I wonder the CAN1 probe may fail here.
>>>>
>>> It can be managed by dts.  Here is what I have in imx28-evk.dts, where
>>> only can0 has phy-enable-gpios property.
>>>
>>>
>>> 	can0: can at 80032000 {
>>> 		pinctrl-names = "default";
>>> 		pinctrl-0 = <&can0_pins_a>;
>>> 		phy-enable-gpios = <&gpio2 13 0>;
>>> 		status = "okay";
>>> 	};
>>>
>>> 	can1: can at 80034000 {
>>> 		pinctrl-names = "default";
>>> 		pinctrl-0 = <&can1_pins_a>;
>>> 		status = "okay";
>>> 	};
>>
>> Will this work if can0 is down and can1 is up?
>>
>> Can we abstract the transceiver power as a regulator? Or a clock? :P
>>
> Hmm, it may not be a power.
> For mx28evk, it's a STBY pin.
> So it may hard to abstract it as a regulator or clock.

I just talked to Sascha, He pointed out, that there already is regulator
that toggles a gpio (only one, not several). I haven't looked at the
details, but a regulator should solve the "two CAN ports share the same
transceiver/phy" problem.

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
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