Re: 4430sdp nfsroot broken with ff5c9059

[Benoit Cousson <b-cousson@ti.com>]

Hi Javier,

On 04/11/2013 01:58 AM, Javier Martinez Canillas wrote:
> On Wed, Apr 10, 2013 at 7:31 PM, Jon Hunter <jon-hunter@ti.com> wrote:
>> Hi Tony,
>>
>> On 04/09/2013 04:23 PM, Tony Lindgren wrote:
>>> Hi Jon,
>>>
>>> Looks like at least 4430sdp nfsroot got broken with commit
>>> ff5c9059 (ARM: dts: OMAP3+: Correct gpio #interrupts-cells
>>> property).
>>
>> Thanks for reporting. I am actually amazed that ethernet is
>> working on any OMAP board (with device-tree) that requires a
>> gpio as an interrupt because we have still not come to an
>> agreement on [1]. Looking at the OMAP4 SDP I believe this is
>> working by luck because there are other gpios in the same
>> bank that are active and so the bank is enabled. If that were
>> not the case then this would not work.
>>
> 
> Hi Jon,
> 
> Ethernet is working on 4430sdp since the optional "gpio" property is
> specified on the fixed regulator used by the eth device node.
> 
> From arch/arm/boot/dts/omap4-sdp.dts:
> 
>         vdd_eth: fixedregulator-vdd-eth {
>                 compatible = "regulator-fixed";
>                 regulator-name = "VDD_ETH";
>                 regulator-min-microvolt = <3300000>;
>                 regulator-max-microvolt = <3300000>;
>                 gpio = <&gpio2 16 0>;  /* gpio line 48 */
>                 enable-active-high;
>                 regulator-boot-on;
>         };
> ...
> &mcspi1 {
>         eth@0 {
>                 compatible = "ks8851";
>                 spi-max-frequency = <24000000>;
>                 reg = <0>;
>                 interrupt-parent = <&gpio2>;
>                 interrupts = <2>; /* gpio line 34 */
>                 vdd-supply = <&vdd_eth>;
>         };
> };
> 
> So is the regulator who is calling gpio_request() and enabling the
> GPIO bank and no the ks881 ethernet driver. That's why it was working
> although I think is just a DT hack and should be changed once we found
> a proper solution to fhis.

It is not really a hack. There is a regulator controlled by a GPIO that
can control the Ethernet chip power. Both gpio48 and gpio34 are used for
Ethernet. On some SDP version there is even a third line, but I was not
able to find any evidence in the schematic I was using.

Regards,
Benoit