Re: cdns_wdt: who enables the clock

Jorge Ramirez-Ortiz, Foundries
2021-09-10T07:56:22Z

On 10/09/21, Michal Simek wrote:
> Hi,
>
> On 9/8/21 5:39 PM, Jorge Ramirez-Ortiz, Foundries wrote:
> > Hi Michal
> >
> > The *linux* cadence_wdt driver for the watchdog enables the clock that
> > controls its behaviour. However this is not done in the U-boot
> > driver; I dont think it is safe to assume that the clock will be active.
> > do you know why is the driver making that assumption? and how to
> > enable the clock?
> >
> > Also, I am not sure it is either safe to assume that the WDT IP will
> > be enabled; IMO during probe we should do something like this
> > (otherwise the AXI bus will complain and fault the boot)
> >
> > static int cdns_wdt_probe(struct udevice *dev)
> > {
> > - debug("%s: Probing wdt%u\n", __func__, dev_seq(dev));
> > + u32 rst = 0;
> > +
> > + /* release WDT from reset */
> > + rst = readl(0xFD1A0100) & ~BIT(15);
> > + writel(rst, 0xFD1A0100);
> > +
> > + debug("%s: Probing wdt%u)\n", __func__, dev_seq(dev));
> >
> > return 0;
> > }
>
> If reset should be perform it should be done via
> drivers/reset/reset-zynqmp.c

ok

>
> It means when you define it in DT you will get reset.

makes sene

>
> I am ok to wire all resets for all IPs to make sure that they are in
> proper state but this has to be tested first.

all right. but yes this particular case was tested.

>
> Thanks,
> Michal
>
> --
> Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
> w: www.monstr.eu p: +42-0-721842854
> Maintainer of Linux kernel - Xilinx Microblaze
> Maintainer of Linux kernel - Xilinx Zynq ARM and ZynqMP ARM64 SoCs
> U-Boot custodian - Xilinx Microblaze/Zynq/ZynqMP/Versal SoCs
>