Disable CM5's RTC to make Yellow's on-board RTC the primary one #3706
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With both RTCs enabled, the rpi_rtc is probed as the first one, making the on-board RTC unused by default. Since the CM5's RTC peripheral can't be used on Yellow, as the VBAT pin is not connected, disable it completely to fix RTC.
📝 WalkthroughWalkthroughThe changes involve a patch to the device tree source file for the Raspberry Pi Compute Module 5 (CM5) specific to the Yellow board. The modification disables the Real-Time Clock (RTC) associated with the Raspberry Pi by adding a status property set to "disabled" in the device tree. This adjustment is necessary because the Yellow board uses its own I2C RTC and lacks the capability to power the RTC peripheral on the CM5. Changes
Sequence Diagram(s)sequenceDiagram
participant YellowBoard
participant CM5
participant RTC
YellowBoard->>CM5: Request RTC status
CM5->>RTC: Check power capability
RTC-->>CM5: No power available
CM5-->>YellowBoard: RTC disabled
📜 Recent review detailsConfiguration used: CodeRabbit UI 📒 Files selected for processing (1)
🔇 Additional comments (2)buildroot-external/board/raspberrypi/yellow/patches/linux/0020-ARM-dts-bcm2712-yellow-Disable-rpi_rtc.patch (2)
The commit message clearly explains the rationale for disabling the RTC - Yellow has its own I2C RTC and CM5's RTC cannot be powered. The patch is properly signed-off.
The changes correctly disable the CM5's RTC:
Let's verify there are no other RTC-related configurations that might need adjustment: ✅ Verification successfulLGTM - RTC configuration is correct and consistent The changes are verified to be correct:
🏁 Scripts executedThe following scripts were executed for the analysis: Script: #!/bin/bash
# Search for any other RTC-related configurations in DTS files
rg -t dts "rpi_rtc|rtc@|compatible.*rtc" arch/arm64/boot/dts/
Length of output: 91 Script: #!/bin/bash
# Search for RTC configurations in all files (not limiting to .dts extension)
rg "rpi_rtc|rtc@|compatible.*rtc" buildroot-external/board/raspberrypi/
Length of output: 641 Script: #!/bin/bash
# Let's examine the content of these RTC-related patches to understand the full context
for file in buildroot-external/board/raspberrypi/yellow/patches/linux/0{008,016,020}-*.patch; do
echo "=== $file ==="
cat "$file"
echo -e "\n\n"
done
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agners
approved these changes
Dec 2, 2024
sairon
added a commit
that referenced
this pull request
Dec 2, 2024
With both RTCs enabled, the rpi_rtc is probed as the first one, making the on-board RTC unused by default. Since the CM5's RTC peripheral can't be used on Yellow, as the VBAT pin is not connected, disable it completely to fix RTC.
sairon
added a commit
that referenced
this pull request
Dec 2, 2024
With both RTCs enabled, the rpi_rtc is probed as the first one, making the on-board RTC unused by default. Since the CM5's RTC peripheral can't be used on Yellow, as the VBAT pin is not connected, disable it completely to fix RTC. (cherry picked from commit 9d643ed)
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With both RTCs enabled, the rpi_rtc is probed as the first one, making the on-board RTC unused by default. Since the CM5's RTC peripheral can't be used on Yellow, as the VBAT pin is not connected, disable it completely to fix RTC.
Summary by CodeRabbit
New Features
Bug Fixes