Messages in this thread | | | Date | Fri, 22 Sep 2023 22:13:05 +0100 | Subject | Re: [PATCH 0/2] arm64: dts: qcom: apq8016-sbc-d3-camera: Convert to DT overlay | From | Bryan O'Donoghue <> |
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On 22/09/2023 21:58, Stephan Gerhold wrote: > On Fri, Sep 22, 2023 at 09:47:07PM +0100, Bryan O'Donoghue wrote: >> On 22/09/2023 16:11, Stephan Gerhold wrote: >>> Follow the example of the recently added apq8016-sbc-usb-host.dtso and >>> convert apq8016-sbc-d3-camera-mezzanine.dts to a DT overlay that can be >>> applied on top of the apq8016-sbc.dtb. This makes it more clear that >>> this is not a special type of DB410c but just an addon board that can >>> be added on top. >>> >>> I also prepended a patch that cleans up the node names a bit. >>> >>> Signed-off-by: Stephan Gerhold <stephan@gerhold.net> >>> --- >>> Stephan Gerhold (2): >>> arm64: dts: qcom: apq8016-sbc-d3-camera: Use more generic node names >>> arm64: dts: qcom: apq8016-sbc-d3-camera: Convert to DT overlay >>> >>> arch/arm64/boot/dts/qcom/Makefile | 5 +++-- >>> ...nine.dts => apq8016-sbc-d3-camera-mezzanine.dtso} | 20 ++++++++++++++------ >>> 2 files changed, 17 insertions(+), 8 deletions(-) >>> --- >>> base-commit: 7236e86ce5c8198b01c30933c2334d07d877cf48 >>> change-id: 20230922-apq8016-sbc-camera-dtso-f247bea40f99 >>> >>> Best regards, >> >> db410c doesn't ship with a bootloader that is capable of applying a dtbo >> though, so this conversion mandates an updated or chainloaded bootloader or >> out-of-tree kernel patch to support. >> >> __adding__ is fine but, converting implies imposes a new requirement on the >> bootchain. >> >> Perhaps a middle road solution is to >> >> - Add, not convert a standalone dtbo or >> - Add a dtbo that includes the mezzanine dts but amends it >> >> Option 2 for preference but, I'm not sure the dts syntax can be meaningfully >> made to do that. >> > > With these patches the apq8016-sbc-d3-camera-mezzanine.dtb is still > magically built, by running fdtoverlay on apq8016-sbc.dtb and applying > the dtbo. It's applied during the build process so you don't need a > bootloader that supports DTBOs. > > There is literally *no change* for you in terms of usage. :-)
Ah I see
+apq8016-sbc-d3-camera-mezzanine-dtbs := apq8016-sbc.dtb apq8016-sbc-d3-camera-mezzanine.dtbo
I guess I like the idea of having the base board dtb a mezzanine.dtb and a dtbo that could be applied as an overlay to the base board dtb, optionally.
Our model then for mezzanine enablement wouild be
1. baseboard.dtb 2. baseboard-mezzanine.dtb 3. baseboard-mezzanine.dtbo
With booting #2 or #1+#3 resulting in the same image but, potentially allowing for
1. baseboard.dtb 2. baseboard-mezzanine.dtb 3. baseboard-mezzanine.dtbo 4. baseboard-some-other-mezzanine.dtb 5. baseboard-some-other-mezzanine.dtbo
#1 + #3 + #5 which would represent a hypothetical stacking of mezzanine boards.
As a model, I think that has merit.
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
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