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    SubjectRe: [PATCH V3 0/9] arm64: imx8mn: Enable more imx8m Nano functions
    On Tue, Nov 23, 2021 at 8:24 AM Lucas Stach <l.stach@pengutronix.de> wrote:
    >
    > Am Dienstag, dem 23.11.2021 um 08:08 -0600 schrieb Adam Ford:
    > > On Mon, Nov 22, 2021 at 3:52 PM Tim Harvey <tharvey@gateworks.com> wrote:
    > > >
    > > > On Mon, Nov 22, 2021 at 10:20 AM Lucas Stach <l.stach@pengutronix.de> wrote:
    > > > >
    > > > > Am Montag, dem 22.11.2021 um 09:59 -0800 schrieb Tim Harvey:
    > > > > > On Sun, Nov 21, 2021 at 7:25 AM Adam Ford <aford173@gmail.com> wrote:
    > > > > > >
    > > > > > > On Sun, Nov 21, 2021 at 8:34 AM Adam Ford <aford173@gmail.com> wrote:
    > > > > > > >
    > > > > > > > On Sun, Nov 21, 2021 at 8:21 AM Fabio Estevam <festevam@gmail.com> wrote:
    > > > > > > > >
    > > > > > > > > Hi Adam,
    > > > > > > > >
    > > > > > > > > On Sun, Nov 21, 2021 at 11:17 AM Adam Ford <aford173@gmail.com> wrote:
    > > > > > > > >
    > > > > > > > > > I am using https://source.codeaurora.org/external/imx/imx-atf/log/?h=lf_v2.4
    > > > > > > > > >
    > > > > > > > > > Since the driver sending SMCC commands to ATF isn't doing that, I
    > > > > > > > > > assume it's safe to use the linux power-domain drivers with the ATF
    > > > > > > > > > from NXP's kernel.
    > > > > > > > > >
    > > > > > > > > > If you can point me to the repo you think I should be using, I'll give it a try.
    > > > > > > > >
    > > > > > > > > Do you know if the mainline TF-A repo v2.5 works too?
    > > > > > > > > https://github.com/ARM-software/arm-trusted-firmware/tree/v2.5
    > > > > > > >
    > > > > > > > That's good to know.
    > > > > > > >
    > > > > > > > I just built it into U-Boot:
    > > > > > > >
    > > > > > > > NOTICE: BL31: v2.5(release):v2.5
    > > > > > > > NOTICE: BL31: Built : 08:24:13, Nov 21 2021
    > > > > > > >
    > > > > > > > The Etnaviv driver is still loading without hanging
    > > > > > > >
    > > > > > > > root@beacon-imx8mn-kit:~# dmesg |grep -i etna
    > > > > > > > [ 12.393936] etnaviv etnaviv: bound 38000000.gpu (ops gpu_ops [etnaviv])
    > > > > > > > [ 12.400676] etnaviv-gpu 38000000.gpu: model: GC7000, revision: 6203
    > > > > > > > [ 12.641297] [drm] Initialized etnaviv 1.3.0 20151214 for etnaviv on minor 0
    > > > > > > >
    > > > > > > >
    > > > > > >
    > > > > > > Tim,
    > > > > > >
    > > > > > > Which version of Nano do you have? Not all Nano SoC's have a GPU from
    > > > > > > looking at the datasheet [1] . I am using MIMX8MN2CVTIZAA (Nano Solo)
    > > > > > >
    > > > > > > [1] - https://www.nxp.com/docs/en/data-sheet/IMX8MNIEC.pdf
    > > > > > >
    > > > > >
    > > > > > Adam,
    > > > > >
    > > > > > The board I have here has MIMX8MN5CVTIZAA so i.MX 8M Nano QuadLite
    > > > > > with 'No GPU' as you expected.
    > > > > >
    > > > > > So I have to add the following to keep my board from hanging after your series:
    > > > > > diff --git a/arch/arm64/boot/dts/freescale/imx8mn-venice-gw7902.dts
    > > > > > b/arch/arm64/boot/dts/freescale/imx8mn-venice-gw7902.dts
    > > > > > index 236f425e1570..0d256a607b7c 100644
    > > > > > --- a/arch/arm64/boot/dts/freescale/imx8mn-venice-gw7902.dts
    > > > > > +++ b/arch/arm64/boot/dts/freescale/imx8mn-venice-gw7902.dts
    > > > > > @@ -251,6 +251,10 @@
    > > > > > };
    > > > > > };
    > > > > >
    > > > > > +&gpu {
    > > > > > + status = "disabled";
    > > > > > +};
    > > > > > +
    > > > > > &i2c1 {
    > > > > > clock-frequency = <100000>;
    > > > > > pinctrl-names = "default";
    > > > > >
    > > > > > This situation is similar to the one I encountered with the
    > > > > > imx8mm-venice-gw7901 where adding the GPC node caused my board (which
    > > > > > did not power the GPU) to hang until I added disables to the
    > > > > > device-tree with commit 7973009235e2 ("arm64: dts:
    > > > > > imx8mm-venice-gw7901.dts: disable pgc_gpumix"). It feels painful to
    > > > > > have to add patches to keep things from hanging after additional
    > > > > > functionality is added to dt but perhaps that is more common than I
    > > > > > think esp for SoC's like IMX8M which have a lot of lingering support
    > > > > > still coming in.
    > > > > >
    > > > > Yea, it's unfortunate that those patches break your board, but I guess
    > > > > we need to accept this, while there is still a lot of feature work
    > > > > going on.
    > >
    > > There are a significant number of peripherals which are defined and
    > > marked as 'disabled' by default, so I don't think it's unreasonable to
    > > do that here.
    > > I'd like to propose we keep the default disabled and people who
    > > need/want the GPU enabled can turn it on. Why waste the power if it's
    > > not needed?
    > >
    > Sure, if a significant number of chips has the GPU disabled, we might
    > want to keep it disabled in the base dtsi. With those variants it's
    > always a tradeoff, for example there are SKUs of the i.MX6 that had the
    > VPU disabled, but very few of those were in the field, so the VPUs are
    > enabled in the SoC base dtsi and only users of those special SKUs would
    > need to disable them in the board DT.
    >
    > The power argument isn't valid, as the kernel driver will suspend the
    > device when not needed, so there is no wasted power (aside from the
    > sort moment while the driver probes) with the GPU enabled.
    >
    > The rule of thumb for when a device is default enabled in the SoC dsti
    > has always been (at least for i.MX) that the peripheral must not have a
    > board level dependency. While a i2c controller obviously needs a i2c
    > bus connected on the board to fulfill its purpose, a GPU can be used as
    > color space converter or something like that with no board level
    > interaction. Now the line is a bit blurred by having multiple power
    > rails into the SoC, so one could argue that the GPUs and VPUs now have
    > some board level dependency on the i.MX8M*.

    That makes sense.

    Do we defer to Shawn as the final arbiter as to whether or not it's
    enabled/disabled? It would be nice to get Nano caught up in
    functionality as much as possible.

    adam

    >
    > Regards,
    > Lucas
    >

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