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Tue, 10 Nov 2026 04:39:16 -0800 (PST) Received: from [192.168.0.15] ([2a02:a312:c59b:a180:251a:f25f:80fa:af1d]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-498363e0019sm5050033f8f.38.2026.11.10.04.39.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Nov 2026 04:39:15 -0800 (PST) From: Artur Kowalski Subject: [PATCH 0/6] watchdog: tegra_wdt: Add Tegra20 support Date: Tue, 10 Nov 2026 13:39:05 +0100 Message-Id: <20261110-t20-for-upstream-v1-0-5923449951fe@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAAAAAAAA/yXMQQrCMBAF0KsMf92BJGgbcxVx0capjmBbJqkIp XcXdfk2b0MRUylItMHkpUXnCYl8Q8j3froJ6xWJEFxovXeRa3A8zsbrUqpJ/+TDqRty1x59jBk NYTEZ9f0rz5e/yzo8JNfvg33/AB/jS+l0AAAA X-Change-ID: 20261108-t20-for-upstream-497bc765188c To: Daniel Lezcano , Thomas Gleixner , Thierry Reding , Jonathan Hunter , Wim Van Sebroeck , Guenter Roeck , Jonathan Corbet , Shuah Khan , Randy Dunlap , Philipp Zabel Cc: linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-doc@vger.kernel.org, clamor95@gmail.com, Artur Kowalski X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=4066; i=arturkow2000@gmail.com; s=default; h=from:subject:message-id; bh=T2iP2KMR8ZGTOcw9sKv5YtssoUQpg/rlCJarXcwIR1M=; b=owGbwMvMwCVmYeTc/TaVxZzxtFoSQ9ZngUKDBQlPouvfurE4vZo4c4ayHdOLveyN34S/hf1b5 vvjG9/GjlIWBjEuBlkxRRazh0JfeOZ5vd/wcmsnzBxWJpAhDFycAjCRCbMY/lkt7jy9ep5b//s5 13bo+Ty3sFBZl7xDW27x1P7A/4fyguUYGQ5JnmK9k3Owbsa6YpU8v4rilYZJK78fMlrlnDOzcrl 3ERMA X-Developer-Key: i=arturkow2000@gmail.com; a=openpgp; fpr=F60710C8D69E03A01A2801CD87A47D20C2709637 The motivation is to improve recovery from kernel hangs which have been steadily driving me to the doorsteps of psych ward for a few months. Those events are rare, some happen at boot, others while trying to use tablet for something real like reading PDFs, browsing web (to the extent possible without working GPU accel), or just using it as thin client for another device. As all my attempts to hunt down even slightest hints of what went down have fallen fouly (device just refuses hang with UART connected), therefore this patch series is born in the hope it will finally enable me and others to catch those bugs (use wdt and pstore). This series adds Tegra20 watchdog support to tegra_wdt. Tegra20's boot ROM hangs if VDE partition is off after warm reset (for normal reboots this is handled by 8f0c714ad9be). The series offers two mitigations: - By default, tegra_wdt stops the watchdog for good before the partition is powered off for the first time, using a new PMC power off notifier (patches 5 and 6). A watchdog started by the bootloader still covers the early boot (until PMC driver comes up). - Booting with tegra_pmc.vde_always_on=1 keeps the partition powered on, so watchdog is fully usable at the expense of higher power consumption. This has been tested on ASUS TF101: - with tegra_pmc.vde_always_on=1, watchdog stays on, the device has been idling for more than hour (heartbeat 10 s, pinged by userspace every 8 s), no issues encountered. Suspend/resume works. On timeout device reboots normally, u-boot still works after warm boot, Linux boots. Tested both with userspace opening watchdog device without pinging, and by crashing the kernel (panic=0). - with tegra_pmc.vde_always_on=0 watchdog is permanently turned off when the PMC driver powers off VDE partition for the first time, after that userspace is denied opening the device with -EBUSY. No issues encountered. Another series for fixing some other issues with warm reboots (not related to watchdog itself) will follow shortly. Patch 4 got flagged by checkpatch (WARNING: ENOSYS means 'invalid syscall nr' and nothing else). I kept it as-is to keep consistency with existing stubs. If this is not desirable just tell me. --- Patch 3 depends on patch 1 and should not be merged before or watchdog driver will conflict with clocksource driver. To: Daniel Lezcano To: Thomas Gleixner To: Thierry Reding To: Jonathan Hunter To: Wim Van Sebroeck To: Guenter Roeck To: Jonathan Corbet To: Shuah Khan To: Randy Dunlap To: Philipp Zabel Cc: linux-kernel@vger.kernel.org Cc: linux-tegra@vger.kernel.org Cc: linux-watchdog@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: clamor95@gmail.com Signed-off-by: Artur Kowalski --- Artur Kowalski (6): clocksource/drivers/timer-tegra: Keep Tegra20's watchdog timers free watchdog: tegra_wdt: Move SoC specific parts into match data watchdog: tegra_wdt: Support Tegra20 soc/tegra: pmc: Add an option to keep the VDE partition on soc/tegra: pmc: Add a partition power off notifier watchdog: tegra_wdt: Stop on Tegra20 VDE power off Documentation/admin-guide/kernel-parameters.txt | 12 + Documentation/watchdog/watchdog-parameters.rst | 5 + drivers/clocksource/timer-tegra.c | 40 ++- drivers/soc/tegra/pmc.c | 158 +++++++++++- drivers/watchdog/tegra_wdt.c | 330 +++++++++++++++++++++++- include/soc/tegra/pmc.h | 19 ++ 6 files changed, 540 insertions(+), 24 deletions(-) --- base-commit: 05441d697f7f9a927264f4058cbbc6a03dfcac9d change-id: 20261108-t20-for-upstream-497bc765188c Best regards, -- Artur Kowalski