On August 26, 2024 thus sayeth Dhruva Gole:

Hi Bryan,

On Aug 23, 2024 at 16:54:30 -0500, Bryan Brattlof wrote:

quoted

ONe power management technique available to the Cortex-A53s is their

s/ONe/One

quoted

ability to dynamically scale their frequency across the device's
Operating Performance Points (OPP)

The OPPs available for the Cortex-A53s on the AM62Px can vary based on
the silicon variant used. The SoC variant is encoded into the
WKUP_MMR0_WKUP0_CTRL_MMR0_JTAG_USER_ID register which is used to limit
the OPP entries the SoC supports. A table of all these variants can be
found in its data sheet[0] for the AM62Px processor family.

Error 404! Not found [0] ;)

Oops. I'll fix these up

quoted

Add the OPP table into the SoC's ftdi file along with the syscon node to

What is ftdi?

FTDI is a chip, what I tried to type out was fdti or Flattened Device 
Tree Includes :)

quoted

describe the WKUP_MMR0_WKUP0_CTRL_MMR0_JTAG_USER_ID register to detect
the SoC variant.

Signed-off-by: Bryan Brattlof <redacted>
---
 .../boot/dts/ti/k3-am62p-j722s-common-wakeup.dtsi  |  5 +++
 arch/arm64/boot/dts/ti/k3-am62p5.dtsi              | 47 ++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/arch/arm64/boot/dts/ti/k3-am62p-j722s-common-wakeup.dtsi b/arch/arm64/boot/dts/ti/k3-am62p-j722s-common-wakeup.dtsi
index 315d0092e7366..6f32135f00a55 100644
--- a/arch/arm64/boot/dts/ti/k3-am62p-j722s-common-wakeup.dtsi
+++ b/arch/arm64/boot/dts/ti/k3-am62p-j722s-common-wakeup.dtsi

@@ -20,6 +20,11 @@ chipid: chipid@14 {
 			bootph-all;
 		};
 
+		opp_efuse_table: syscon@18 {
+			compatible = "ti,am62-opp-efuse-table", "syscon";

Huh, curious why I don't see this particular compatible in am62 itself..
Also, I am still not clear where this discussion got left off: (If it's
related)
https://lore.kernel.org/all/5chxjwybmsxq73pagtlw4zr2asbtxov7ezrpn5j37cr77bmepa@fejdlxomfgae/ (local)

In AM625, I see
k3-am625.dtsi:111: col 14: syscon = <&wkup_conf>;

But the approach you've used here seems different. Is there a
justification given on which one should be used/why somewhere that I can
refer?

Labeling the entire &wkup_conf as a syscon node is kinda abusing what 
the syscon node is used for. There are a lot of things inside that 
WKUP_CTRL_MMR that do not belong under the miscellaneous registers 
category. For the 62A and 62P we've chosen to label &wkup_conf as a bus 
with little syscon sub-nodes inside of it.  

I don't think the discussion[0] ever finalized but we started going that 
direction with new SoCs, looks like the older SoCs never received the 
cleanup.

~Bryan

[0] https://lore.kernel.org/all/e7114cb4-e24f-4e78-a89f-4e2e2e704b8a@ti.com/ (local)