[linux-sunxi] Re: [PATCH v2 19/21] arm64: dts: allwinner: Add Allwinner H616 .dtsi file

[Maxime Ripard]

On Mon, Dec 14, 2020 at 09:28:36PM +0800, Chen-Yu Tsai wrote:
> On Mon, Dec 14, 2020 at 8:53 PM Andre Przywara <andre.przywara at arm.com> wrote:
> >
> > On Mon, 14 Dec 2020 10:58:31 +0100
> > Maxime Ripard <maxime at cerno.tech> wrote:
> >
> > Hi,
> >
> > > On Fri, Dec 11, 2020 at 01:19:32AM +0000, Andre Przywara wrote:
> > > > +   reserved-memory {
> > > > +           #address-cells = <2>;
> > > > +           #size-cells = <2>;
> > > > +           ranges;
> > > > +
> > > > +           /* 512KiB reserved for ARM Trusted Firmware (BL31)
> > > > */
> > > > +           secmon_reserved: secmon at 40000000 {
> > > > +                   reg = <0x0 0x40000000 0x0 0x80000>;
> > > > +                   no-map;
> > > > +           };
> > > > +   };
> > >
> > > This should still be set by the firmware
> > >
> > > > +           mmc0: mmc at 4020000 {
> > > > +                   compatible = "allwinner,sun50i-h616-mmc",
> > > > +                                "allwinner,sun50i-a100-mmc";
> > > > +                   reg = <0x04020000 0x1000>;
> > > > +                   clocks = <&ccu CLK_BUS_MMC0>, <&ccu
> > > > CLK_MMC0>;
> > > > +                   clock-names = "ahb", "mmc";
> > > > +                   resets = <&ccu RST_BUS_MMC0>;
> > > > +                   reset-names = "ahb";
> > > > +                   interrupts = <GIC_SPI 35
> > > > IRQ_TYPE_LEVEL_HIGH>;
> > > > +                   pinctrl-names = "default";
> > > > +                   pinctrl-0 = <&mmc0_pins>;
> > > > +                   status = "disabled";
> > > > +                   #address-cells = <1>;
> > > > +                   #size-cells = <0>;
> > > > +           };
> > >
> > > Somewhat related: we shouldn't set the MMC speed flags in the drivers.
> > > This is biting us on the already supported SoCs, so it would be great
> > > to not repeat the same mistake with the new ones
> >
> > Do you mean to list the "sd-uhs-sdr50" and friends properties here in
> > the DT?
> > What is the best practice here in terms putting them in the .dts vs.
> > the .dtsi? Surely the controller has limits, but bad traces on a board
> > could impose further restrictions, right?
> > Though that's probably rare, so it sounds like a lot of churn to list
> > them in every board DT. So can we list everything in here (.dtsi), then
> > delete in those affected boards only?
> 
> The driver will most certainly already have the basic high speed modes
> enabled. Or we can list them in the .dtsi file.

I'd list them all in the DTSI, trying to be smart has bitten us already
so I'd like to avoid it as much as possible.

And if we find a better way, we can set it in the driver if it's in the
DTSI already. doing the opposite would be harder

Maxime
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