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From:   Rob Herring <robh+dt@kernel.org>
Date:   Fri, 22 Sep 2023 15:09:06 -0500
Message-ID: <CAL_JsqLmv904+_2EOmsQ__y1yLDvsT+_02i85phuh0cpe7X8NQ@mail.gmail.com>
Subject: Re: [PATCH 2/2] arm64: dts: ti: am642-evm: Add overlay for NAND
 expansion card
To:     Roger Quadros <rogerq@kernel.org>
Cc:     Andrew Davis <afd@ti.com>, Nishanth Menon <nm@ti.com>,
        Tony Lindgren <tony@atomide.com>, david@gibson.dropbear.id.au,
        vigneshr@ti.com, krzysztof.kozlowski+dt@linaro.org,
        conor+dt@kernel.org, srk@ti.com,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Siddharth Vadapalli <s-vadapalli@ti.com>
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On Fri, Sep 22, 2023 at 4:03=E2=80=AFAM Roger Quadros <rogerq@kernel.org> w=
rote:
>
>
>
> On 21/09/2023 20:23, Andrew Davis wrote:
> > On 9/21/23 6:37 AM, Roger Quadros wrote:
> >> On 20/09/2023 20:06, Andrew Davis wrote:
> >>> On 9/20/23 11:44 AM, Nishanth Menon wrote:
> >>>> On 18:18-20230920, Roger Quadros wrote:
> >>>>>
> >>>>>
> >>>>> On 20/09/2023 16:58, Nishanth Menon wrote:
> >>>>>> On 16:34-20230920, Roger Quadros wrote:
> >>>>>>> The NAND expansion card plugs in over the HSE (High Speed Expansi=
on)
> >>>>>>> connector. Add support for it.
> >>>>>>>
> >>>>>>> Signed-off-by: Roger Quadros <rogerq@kernel.org>
> >>>>>>> ---
> >>>>>>>    arch/arm64/boot/dts/ti/Makefile               |   1 +
> >>>>>>>    arch/arm64/boot/dts/ti/k3-am642-evm-nand.dtso | 140 ++++++++++=
++++++++
> >>>>>>>    2 files changed, 141 insertions(+)
> >>>>>>>    create mode 100644 arch/arm64/boot/dts/ti/k3-am642-evm-nand.dt=
so
> >>>>>>>
> >>>>>>> diff --git a/arch/arm64/boot/dts/ti/Makefile b/arch/arm64/boot/dt=
s/ti/Makefile
> >>>>>>> index 06d6f264f292..ece74085a6be 100644
> >>>>>>> --- a/arch/arm64/boot/dts/ti/Makefile
> >>>>>>> +++ b/arch/arm64/boot/dts/ti/Makefile
> >>>>>>> @@ -29,6 +29,7 @@ dtb-$(CONFIG_ARCH_K3) +=3D k3-am62p5-sk.dtb
> >>>>>>>      # Boards with AM64x SoC
> >>>>>>>    dtb-$(CONFIG_ARCH_K3) +=3D k3-am642-evm.dtb
> >>>>>>> +dtb-$(CONFIG_ARCH_K3) +=3D k3-am642-evm-nand.dtbo
> >>>>>>>    dtb-$(CONFIG_ARCH_K3) +=3D k3-am642-phyboard-electra-rdk.dtb
> >>>>>>>    dtb-$(CONFIG_ARCH_K3) +=3D k3-am642-sk.dtb
> >>>>>>>    dtb-$(CONFIG_ARCH_K3) +=3D k3-am642-tqma64xxl-mbax4xxl.dtb
> >>>>>>
> >>>>>> Also see https://lore.kernel.org/all/20230911165610.GA1362932-robh=
@kernel.org/
> >>>>>>
> >>>>>> you may not get the dtbo installed when doing make dtbs_install
> >>>>>>
> >>>>>> [...]
> >>>>>>
> >>>>>
> >>>>> $ v8make dtbs_install INSTALL_DTBS_PATH=3D/tmp
> >>>>>     INSTALL /tmp/ti/k3-am625-beagleplay.dtb
> >>>>>     INSTALL /tmp/ti/k3-am625-phyboard-lyra-rdk.dtb
> >>>>>     INSTALL /tmp/ti/k3-am625-sk.dtb
> >>>>>     INSTALL /tmp/ti/k3-am625-verdin-nonwifi-dahlia.dtb
> >>>>>     INSTALL /tmp/ti/k3-am625-verdin-nonwifi-dev.dtb
> >>>>>     INSTALL /tmp/ti/k3-am625-verdin-nonwifi-yavia.dtb
> >>>>>     INSTALL /tmp/ti/k3-am625-verdin-wifi-dahlia.dtb
> >>>>>     INSTALL /tmp/ti/k3-am625-verdin-wifi-dev.dtb
> >>>>>     INSTALL /tmp/ti/k3-am625-verdin-wifi-yavia.dtb
> >>>>>     INSTALL /tmp/ti/k3-am62-lp-sk.dtb
> >>>>>     INSTALL /tmp/ti/k3-am62x-sk-hdmi-audio.dtbo
> >>>>>     INSTALL /tmp/ti/k3-am62a7-sk.dtb
> >>>>>     INSTALL /tmp/ti/k3-am62p5-sk.dtb
> >>>>>     INSTALL /tmp/ti/k3-am642-evm.dtb
> >>>>>     INSTALL /tmp/ti/k3-am642-evm-nand.dtbo
> >>>>> ^^^^
> >>>>>     INSTALL /tmp/ti/k3-am642-phyboard-electra-rdk.dtb
> >>>>>     INSTALL /tmp/ti/k3-am642-sk.dtb
> >>>>>
> >>>>>
> >>>>> What did I miss?
> >>>>
> >>>> I missed it, actually. See Rob's comment:
> >>>> https://lore.kernel.org/all/CAL_Jsq+GR3hP6hFvFn2z5aXvSXnh9butD3aKZ-y=
_XJgx0_YPTw@mail.gmail.com/
> >>>>
> >>>> Having orphan dtbo is apparently frowned upon
> >>>>
> >>>
> >>> And if you apply these overlays to the base DTB then it gets
> >>> symbols added automatically, no need for your patch [1/2] here.
> >>>
> >>
> >> Is this OK?
> >>
> >>     k3-am642-evm-nand-dtbs :=3D k3-am642-evm.dtb k3-am642-evm-nand.dtb=
o
> >>     dtb-$(CONFIG_ARCH_K3) +=3D k3-am642-evm-nand.dtb
> >>
> >> So patch 1 is not required in this case but we have an
> >> extra dtb file which is not really required.
> >>
> >
> > While I agree we will end up with several pre-overlayed DTB files
> > that are arguably not required as they could be later built/applied,
> > until we find a better way to check at build time these overlays
> > need applied to something as a test.
> >
> >> I have 2 more issues to point out
> >>
> >> 1)
> >> With existing examples e.g. J7200 EVM
> >> wouldn't  k3-j7200-evm.dtb include the k3-j7200-evm-quad-port-eth-exp.=
dtbo?
> >> Is this what we really want?
> >>
> >> likewise for k3-j721e-evm.dtb and k3-am654-gp-evm.dtb
> >>
> >
> > Yes, that is the idea, the base-board.dtb is just the raw main board, b=
ut
> > the "EVM" when you buy it comes with the quad-port daughtercard attache=
d.
> > That is what we consider the "EVM" and the DTB names match that.
> >
> >> 2)
> >> Another issue (unrelated to this change) is the below warning:
> >>
> >>     arch/arm64/boot/dts/ti/k3-am642-evm-nand.dtso:65.8-140.3: Warning =
(avoid_default_addr_size): /fragment@3/__overlay__: Relying on default #add=
ress-cells value
> >>     arch/arm64/boot/dts/ti/k3-am642-evm-nand.dtso:65.8-140.3: Warning =
(avoid_default_addr_size): /fragment@3/__overlay__: Relying on default #siz=
e-cells value
> >>
> >> This is because we use the 'ranges' property in the gpmc0 node
> >> and the compiler doesn't know the #address/size-cells of the
> >> parent node.
> >>
> >> Is there a trick to specify it in the dtso file?
> >>
> >
> > Hmm, seems like a tricky one. Do you really need to do the ranges here?
> > Could you use the default `ranges;` for gpmc0? Then do the range transl=
ation
> > down inside the nand node to keep the partition addresses sane.
>
> GPMC has separate address spaces per chip select.
>
> From Documentation/devicetree/bindings/memory-controllers/ti,gpmc.yaml
>   ranges:
>     minItems: 1
>     description: |
>       Must be set up to reflect the memory layout with four
>       integer values for each chip-select line in use,
>       <cs-number> 0 <physical address of mapping> <size>
>
> The ranges location in the device tree overlay is correct. The overlay is
> meaningless without the base tree.
>
> The correct solution would be to fix dtc so it doesn't print this warning
> for DT overlays.

https://www.spinics.net/lists/devicetree-compiler/msg04036.html