[PATCH] usb: ehci-mx6: replace regulator_set_enable with *_if_allowed

Marek Vasut marex at denx.de
Tue May 2 12:53:15 CEST 2023

On 5/2/23 12:41, Eugen Hristev wrote:
> On 5/2/23 12:18, Marek Vasut wrote:
>> On 5/2/23 08:51, Eugen Hristev wrote:
>>> regulator_set_enable_if_allowed already handles cases when the
>>> regulator is already enabled, or already disabled, and does not
>>> treat these as errors.
>>> With this change, the driver can work correctly even if the regulator
>>> is already taken or already disabled by another consumer.
>> Can that ever happen for Vbus supply (the 5V coming out of USB port) ?
>> Can you elaborate how ?
> Hi Marek,


> Recently I developed a series of patches to add a reference counter for 
> regulators :
> https://marc.info/?l=u-boot&m=168191189309879&w=2

Ah yes, this is super cool stuff, thanks !

> But with this series, having a regulator already enabled or already 
> disabled results in an error returned by regulator_set_enable
> Hence, one option is to replace calls with regulator_set_enable_if_allowed
> There is a discussion ongoing here:
> https://marc.info/?l=u-boot&m=168295920316621&w=2

Pardon my ignorance, but uh ... how does Linux deal with regulators 
which are enabled by prior stage, like U-Boot ? Does it set their enable 
refcount to =1 or =0 ?

More information about the U-Boot mailing list