Re: [PATCH] usb: host: ohci-at91: add support to enter suspend using SMC

[Clément Léger]

Le Mon, 6 Jun 2022 14:12:52 -0400,
Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> a écrit :

> On Mon, Jun 06, 2022 at 04:18:02PM +0200, Clément Léger wrote:
> > When Linux is running under OP-TEE, the SFR is set as secured and thus
> > the AT91_OHCIICR_USB_SUSPEND register isn't accessible. Add a SMC to
> > do the appropriate call to suspend the controller.
> > The SMC id is fetched from the device-tree property
> > "microchip,suspend-smc-id". if present, then the syscon regmap is not
> > used to enter suspend and a SMC is issued.
> > 
> > Signed-off-by: Clément Léger <clement.leger@xxxxxxxxxxx>
> > ---  
> 
> Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> 
> However, this is a little weird...  You've written 
> usb_hcd_at91_probe() so that the SMC is detected in preference to the 
> regmap, but then you wrote ohci_at91_port_suspend() so that the regmap 
> is used in preference to the SMC.  It's not wrong, but it is confusing 
> to read.
> 
> Do you want to rewrite the patch to make the two routines agree on which 
> mechanism to use by default?
> 
> Alan Stern

Hi Alan,

I'll rewrite that ! I did it in this specific order in the probe to
allow overloading the device-tree with a SMC ID without removing the
syscon property. This way, the regmap stays the default if no
"microchip,suspend-smc-id" property is provided.

Does it sounds good to you ?

Thanks,

-- 
Clément Léger,
Embedded Linux and Kernel engineer at Bootlin
https://bootlin.com