Re: [PATCH 2/2] arm64: dts: ti: am642-evm: Add overlay for NAND expansion card

[Andrew Davis <afd@ti.com>]

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 Expansion)
>>>>>> 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.dtso
>>>>>>
>>>>>> diff --git a/arch/arm64/boot/dts/ti/Makefile b/arch/arm64/boot/dts/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-$(CONFIG_ARCH_K3) += k3-am62p5-sk.dtb
>>>>>>      # Boards with AM64x SoC
>>>>>>    dtb-$(CONFIG_ARCH_K3) += k3-am642-evm.dtb
>>>>>> +dtb-$(CONFIG_ARCH_K3) += k3-am642-evm-nand.dtbo
>>>>>>    dtb-$(CONFIG_ARCH_K3) += k3-am642-phyboard-electra-rdk.dtb
>>>>>>    dtb-$(CONFIG_ARCH_K3) += k3-am642-sk.dtb
>>>>>>    dtb-$(CONFIG_ARCH_K3) += 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=/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 := k3-am642-evm.dtb k3-am642-evm-nand.dtbo
> 	dtb-$(CONFIG_ARCH_K3) += 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, but
the "EVM" when you buy it comes with the quad-port daughtercard attached.
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 #address-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 #size-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 translation
down inside the nand node to keep the partition addresses sane.

Andrew