[PATCH v3 12/14] dts: sdm845-db845c: add u-boot fixups

[Caleb Connolly]

On 20/03/2024 12:33, Caleb Connolly wrote:
> 
> 
> On 19/03/2024 13:55, Sumit Garg wrote:
>> On Tue, 19 Mar 2024 at 17:52, Caleb Connolly <caleb.connolly at linaro.org> wrote:
>>>
>>> The USB VBUS supply for the type-A port is enabled via a GPIO regulator.
>>> This is incorrectly modelled in Linux where only the PCIe dependency is
>>> expressed.
>>
>> Can we send a fix for the Linux kernel DTS to correctly model it? We
>> can then later get rid of this modification once that is accepted.
> 
> I spoke to Bjorn about this and apparently the correct way to model this
> will be to have a usb-connector node with a vbus-supply property. There
> is some work underway in Linux to support this kind of thing already.
> 
> In the mean time he suggested to just make the regulator always-on, so I
> sent a patch to do that [1]. I actually hit this issue when booting from
> USB as the PCIe drivers aren't available in the initramfs, so USB never
> turns on, and the always-on hack fixes that.
> 
> In the mean time, we'll still need this vbus-supply reference as U-Boot
> doesn't automatically probe regulators.

oh, forgot the link!

[1]:
https://lore.kernel.org/linux-arm-msm/20240320122515.3243711-1-caleb.connolly@linaro.org/
>>
>> -Sumit
>>
>>> Add a U-Boot specific dtsi snippet so that this supply will
>>> get enabled when initialising USB.
>>>
>>> Signed-off-by: Caleb Connolly <caleb.connolly at linaro.org>
>>> ---
>>>  arch/arm/dts/sdm845-db845c-u-boot.dtsi | 8 ++++++++
>>>  1 file changed, 8 insertions(+)
>>>
>>> diff --git a/arch/arm/dts/sdm845-db845c-u-boot.dtsi b/arch/arm/dts/sdm845-db845c-u-boot.dtsi
>>> new file mode 100644
>>> index 000000000000..3c83e21251c4
>>> --- /dev/null
>>> +++ b/arch/arm/dts/sdm845-db845c-u-boot.dtsi
>>> @@ -0,0 +1,8 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +
>>> +/* This GPIO must be turned on to enable the 5v VBUS
>>> + * supply on the USB port.
>>> + */
>>> +&usb_2_dwc3 {
>>> +       vbus-supply = <&pcie0_3p3v_dual>;
>>> +};
>>>
>>> --
>>> 2.44.0
>>>
> 

-- 
// Caleb (they/them)