Re: [PATCH] arm64: dts: mt8192: Add adsp power domain controller
From: Chen-Yu Tsai
Date: Thu Dec 01 2022 - 05:05:59 EST
On Thu, Dec 1, 2022 at 5:39 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@xxxxxxxxxxxxx> wrote:
>
> Il 01/12/22 10:10, Chen-Yu Tsai ha scritto:
> > On Thu, Dec 1, 2022 at 5:07 PM AngeloGioacchino Del Regno
> > <angelogioacchino.delregno@xxxxxxxxxxxxx> wrote:
> >>
> >> Il 01/12/22 08:33, Allen-KH Cheng ha scritto:
> >>> Add adsp power domain controller node for mt8192 SoC.
> >>>
> >>> Signed-off-by: Allen-KH Cheng <allen-kh.cheng@xxxxxxxxxxxx>
> >>> ---
> >>> Ref: https://lore.kernel.org/all/2ec80bd8-dfef-d2e6-eb41-6e6088043e33@xxxxxxxxxxxxx/
> >>> [Allen-KH Cheng <allen-kh.cheng@xxxxxxxxxxxx>]
> >>> ---
> >>> ---
> >>> arch/arm64/boot/dts/mediatek/mt8192.dtsi | 8 ++++++++
> >>> include/dt-bindings/power/mt8192-power.h | 1 +
> >>> 2 files changed, 9 insertions(+)
> >>>
> >>
> >> Allen, thanks for this one, but it's incomplete...
> >>
> >> First of all, you must add the power domain on the driver itself, specifically,
> >> in drivers/soc/mediatek/mt8192-pm-domains.h - otherwise this change will have no
> >> effect!
> >
> > Actually it's worse. The driver doesn't know about the new power domain,
> > and so it will fail to probe. We might need to make the power domain driver
> > fail gracefully and skip unknown power domains.
> >
>
> Right. It's worse. I don't know, though, if gracefully skipping unknown power
> domains in the driver would be a good decision... as sometimes error messages
> go unnoticed.
>
> When the platform "explodes" instead, you're forced to read that log carefully
> and get it working again... Anyway, I'm only thinking out loud, nothing less and
> nothing more than that :-)
Me too. :)
> By the way, we can probably expand on that topic a bit later, as it's outside of
> the scope of this specific change.
>
> Back to topic, if we get one series containing both changes (devicetree, bindings
> and driver) with the right Fixes tags and/or Cc stable, we shouldn't have such
> issue on backports so we can probably ignore that potential issue, I think? :-)
Everything goes through the soc tree, so they should appear in Linus's tree
and get picked by stable at more or less the same time. I think we would
want the driver change to appear before the dts change, for bisectability's
sake (because of header dependencies and driver errors).
So we probably want:
1. driver + binding header changes
2. dtsi changes
And have these merged through fixes so that the history between them is linear.
ChenYu
> Cheers,
> Angelo
>
> > ChenYu
> >
> >> ...Then, as Chen-Yu said, you should also add the power domain to the scp_adsp
> >> clock node as that's solving the lockup issue...
> >>
> >> .......and last, but not least: we need a Fixes tag to backport this fix, here
> >> and on the commit that adds the missing power domain in the driver.
> >>
> >> Thanks,
> >> Angelo
> >>
> >>> diff --git a/arch/arm64/boot/dts/mediatek/mt8192.dtsi b/arch/arm64/boot/dts/mediatek/mt8192.dtsi
> >>> index 424fc89cc6f7..e71afba871fc 100644
> >>> --- a/arch/arm64/boot/dts/mediatek/mt8192.dtsi
> >>> +++ b/arch/arm64/boot/dts/mediatek/mt8192.dtsi
> >>> @@ -514,6 +514,14 @@
> >>> };
> >>> };
> >>> };
> >>> +
> >>> + power-domain@MT8192_POWER_DOMAIN_ADSP {
> >>> + reg = <MT8192_POWER_DOMAIN_ADSP>;
> >>> + clocks = <&topckgen CLK_TOP_ADSP_SEL>;
> >>> + clock-names = "adsp";
> >>> + mediatek,infracfg = <&infracfg>;
> >>> + #power-domain-cells = <0>;
> >>> + };
> >>> };
> >>> };
> >>>
> >>> diff --git a/include/dt-bindings/power/mt8192-power.h b/include/dt-bindings/power/mt8192-power.h
> >>> index 4eaa53d7270a..63e81cd0d06d 100644
> >>> --- a/include/dt-bindings/power/mt8192-power.h
> >>> +++ b/include/dt-bindings/power/mt8192-power.h
> >>> @@ -28,5 +28,6 @@
> >>> #define MT8192_POWER_DOMAIN_CAM_RAWA 18
> >>> #define MT8192_POWER_DOMAIN_CAM_RAWB 19
> >>> #define MT8192_POWER_DOMAIN_CAM_RAWC 20
> >>> +#define MT8192_POWER_DOMAIN_ADSP 21
> >>>
> >>> #endif /* _DT_BINDINGS_POWER_MT8192_POWER_H */
> >>>
> >>
>
>