Re: [Buildroot] [PATCH v5 2/6] board/raspberrypicm4io: enable RTC and USB overlays

[Peter Seiderer <ps.report@gmx.net>]

Hello Yann,

On Sun, 17 Oct 2021 22:27:17 +0200, "Yann E. MORIN" <yann.morin.1998@free.fr> wrote:

> Peter, All,
>
> On 2021-09-21 22:21 +0200, Peter Seiderer spake thusly:
> > - add RTC and USB dtoverlay entries to config_cm4io.txt
>
> Why specifically the RTC and USB? And why only on the CM, and not the
> other boards?

The config is not for the CM4 standalone, but specific to the
CM4 IO Board, equipped (as the only RPi original one) with an
RTC chip....

>
> IIRC, dwc2 is an OTG chip, too, and it is also wired on the rpi0. Well,
> by experience, I know that the rpi0 *can* do USB slave/OTG.

And as far as I know the USB is enabled with all RPi's with
exception of the CM4: 'The  USB  interface  is  disabled  to  save  power  by
default  on  the  CM4' (see [1] page 5)

According to [2]:

	Name:   dwc-otg
	Info:   Selects the dwc_otg USB controller driver which has fiq support. This
	        is the default on all except the Pi Zero which defaults to dwc2.
	Load:   dtoverlay=dwc-otg
	Params: <None>


	Name:   dwc2
	Info:   Selects the dwc2 USB controller driver
	Load:   dtoverlay=dwc2,<param>=<val>
	Params: dr_mode                 Dual role mode: "host", "peripheral" or "otg"

	        g-rx-fifo-size          Size of rx fifo size in gadget mode

	        g-np-tx-fifo-size       Size of non-periodic tx fifo size in gadget
	                                mode

Would interpret 'defaults to dwc2' on Pi Zero as enabled by default...

Regards,
Peter

[1] https://datasheets.raspberrypi.com/cm4io/cm4io-datasheet.pdf
[2] https://github.com/raspberrypi/firmware/blob/master/boot/overlays/README
>
>
> Regards,
> Yann E. MORIN.
>
> > Signed-off-by: Peter Seiderer <ps.report@gmx.net>
> > ---
> > Changes v4 -> v5:
> >   - new patch
> > ---
> >  board/raspberrypi/config_cm4io.txt | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/board/raspberrypi/config_cm4io.txt b/board/raspberrypi/config_cm4io.txt
> > index 01f60395b3..cf7e6df1a1 100644
> > --- a/board/raspberrypi/config_cm4io.txt
> > +++ b/board/raspberrypi/config_cm4io.txt
> > @@ -24,3 +24,10 @@ gpu_mem_1024=100
> >
> >  # fixes rpi (3B, 3B+, 3A+, 4B and Zero W) ttyAMA0 serial console
> >  dtoverlay=miniuart-bt
> > +
> > +# enable RTC
> > +dtparam=i2c_vc=on
> > +dtoverlay=i2c-rtc,pcf85063a,i2c_csi_dsi
> > +
> > +# enable dwc2 USB controller (USB 2.0)
> > +dtoverlay=dwc2,dr_mode=host
> > --
> > 2.33.0
> >
> > _______________________________________________
> > buildroot mailing list
> > buildroot@lists.buildroot.org
> > https://lists.buildroot.org/mailman/listinfo/buildroot
>

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