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rtc: armada38x: disable update interrupt feature#595

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fountzou:disable_uie_in_armada_driver
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rtc: armada38x: disable update interrupt feature#595
fountzou wants to merge 1 commit into
sonic-net:masterfrom
fountzou:disable_uie_in_armada_driver

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@fountzou

@fountzou fountzou commented Jul 1, 2026

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Stop advertising update interrupts for the armada38x RTC driver.

SONiC switched to chrony, which enables RTC update interrupts via the RTC_UIE_ON ioctl. On the armada38x RTC driver, big skew in time can lead to pinning the CPU and triggering the RCU stall and reboot.
We clear the RTC_FEATURE_UPDATE_INTERRUPT at probe time, so RTC_UIE_ON no longer takes the native periodic-timer path and instead routes to the UIE emulation path (dbd69ff).

Stop advertising update interrupts for the armada38x RTC driver

Signed-off-by: fountzou <ioannis.fountzoulas@nokia.com>
@fountzou fountzou requested a review from a team as a code owner July 1, 2026 16:13
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/azp run

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@Pavan-Nokia

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@lizhijianrd @saiarcot895 Please help review. This is an alternate fix for the RTC issue

@paulmenzel paulmenzel left a comment

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Thank you. Please send the patch upstream for review.

@@ -0,0 +1,25 @@
From 97dafb76ffc08cbac6bca2568e8d179d7f2f3632 Mon Sep 17 00:00:00 2001
From: fountzou <ioannis.fountzoulas@nokia.com>

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Please use your full name.

From: fountzou <ioannis.fountzoulas@nokia.com>
Date: Wed, 1 Jul 2026 11:50:21 -0400
Subject: [PATCH] Clear UIE bit from armada38x RTC driver

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Please add a commit message suitable for Linux upstream. (What is the problem? How is it fixed and tested? Please also detail why the CPU hangs, and if it’s an hardware issue.)

else
clear_bit(RTC_FEATURE_ALARM, rtc->rtc_dev->features);

+ clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->rtc_dev->features);

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4 participants