From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A2CBF70809 for ; Sun, 5 Jul 2026 01:06:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783213585; cv=none; b=Y/1/9YSbm4GKRtfYfxVaBlrIBahHoVMGb3vvTdMCRbItK0aFfyz7Zw4OYIffc6oDnWGMwiA2cgPMVRjtykqBfu7KLKmOXKxN9Y7ZSrMaSZZNxvef2YR1i0T8n5SNfcqGPub42RK72hTWmIudYDnCTJtnx7cVIU0fTkt3v/tIOQc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783213585; c=relaxed/simple; bh=5wqE2H94b2eAJ0crbFTbb00/F/9UxU1uAnvrYGaqnHc=; h=Date:To:From:Subject:Message-Id; b=h8nLdean/7cjQiGNG5w6eFlIzjs7plyRFNFM2hfiBETnk73YsugSk4CXlPPu3x35H/f+hdozbVJfVynEYAWeJxdm4ZuAChYzZKFJfWSN2Q1PE1a9MLb4xGe5uS1pi0t2JhINb7W67bkcoA9bV7xe9FdEXSmSg7qc7+mWQRsQ3iU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=2W7f7hqG; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="2W7f7hqG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2EC821F000E9; Sun, 5 Jul 2026 01:06:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1783213584; bh=AisfbAonOOvmfNNDDq41ZEU+ao5TFZlPfC3+YC2Ti5E=; h=Date:To:From:Subject; b=2W7f7hqGjonz2WKAmmFvjnqhS7+YcGeujIdT7N3YtAFW1BsRrpZwcMGHDVJ6mqCbY 1A2CeyxIf1GRapTmPKEkL2aShXoBP3tW/t5gTSdq+1h+3VsVTbDypaLnzfStL8jr6X 2ZpXZ+rNk+XIMQIxRPB+8RvFOSTSYdu51hz64Epk= Date: Sat, 04 Jul 2026 18:06:23 -0700 To: mm-commits@vger.kernel.org,giometti@enneenne.com,calvin@wbinvd.org,bigeasy@linutronix.de,by@by-online.de,akpm@linux-foundation.org From: Andrew Morton Subject: + pps-pps-gpio-split-irq-handler-into-hardirq-timestamper-threaded-handler.patch added to mm-nonmm-unstable branch Message-Id: <20260705010624.2EC821F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: pps: pps-gpio: split IRQ handler into hardirq timestamper + threaded handler has been added to the -mm mm-nonmm-unstable branch. Its filename is pps-pps-gpio-split-irq-handler-into-hardirq-timestamper-threaded-handler.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/pps-pps-gpio-split-irq-handler-into-hardirq-timestamper-threaded-handler.patch This patch will later appear in the mm-nonmm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Michael Byczkowski Subject: pps: pps-gpio: split IRQ handler into hardirq timestamper + threaded handler Date: Mon, 1 Jun 2026 17:44:09 -0700 Split the pps-gpio interrupt handler into a primary (hardirq) handler that captures the PPS timestamp at interrupt entry, and a threaded handler that processes the event. This produces the same two-part handler structure on both PREEMPT_RT and non-RT kernels. On non-RT kernels the threaded portion runs immediately after the primary, with no behavioral change compared to the previous single-handler implementation. On PREEMPT_RT, where interrupt handlers are force-threaded by default, the previous single-handler implementation captured the timestamp inside the threaded portion, after IRQ-thread scheduling delay. With the split, the timestamp is captured in true hardirq context as it is on non-RT kernels, eliminating a significant source of PPS jitter on RT systems. Link: https://lore.kernel.org/2e32729029fbf6977ecf04665eb00f2efd3e2c17.1780359378.git.calvin@wbinvd.org Signed-off-by: Michael Byczkowski Signed-off-by: Calvin Owens Reviewed-by: Sebastian Andrzej Siewior Tested-by: Michael Byczkowski Tested-by: Calvin Owens Acked-by: Rodolfo Giometti Signed-off-by: Andrew Morton --- drivers/pps/clients/pps-gpio.c | 37 ++++++++++++++++++++----------- 1 file changed, 25 insertions(+), 12 deletions(-) --- a/drivers/pps/clients/pps-gpio.c~pps-pps-gpio-split-irq-handler-into-hardirq-timestamper-threaded-handler +++ a/drivers/pps/clients/pps-gpio.c @@ -35,33 +35,44 @@ struct pps_gpio_device_data { bool capture_clear; unsigned int echo_active_ms; /* PPS echo active duration */ unsigned long echo_timeout; /* timer timeout value in jiffies */ + struct pps_event_time ts; /* timestamp captured in hardirq */ }; /* * Report the PPS event */ -static irqreturn_t pps_gpio_irq_handler(int irq, void *data) +/* + * Primary hardirq handler -- runs in hardirq context even on PREEMPT_RT. + * Only captures the timestamp; all other work is deferred to the thread. + */ +static irqreturn_t pps_gpio_irq_hardirq(int irq, void *data) { - const struct pps_gpio_device_data *info; - struct pps_event_time ts; - int rising_edge; + struct pps_gpio_device_data *info = data; + + pps_get_ts(&info->ts); - /* Get the time stamp first */ - pps_get_ts(&ts); + return IRQ_WAKE_THREAD; +} - info = data; +/* + * Threaded handler -- processes the PPS event using the timestamp + * captured in hardirq context above. + */ +static irqreturn_t pps_gpio_irq_thread(int irq, void *data) +{ + struct pps_gpio_device_data *info = data; + int rising_edge; - /* Small trick to bypass the check on edge's direction when capture_clear is unset */ rising_edge = info->capture_clear ? gpiod_get_value(info->gpio_pin) : !info->assert_falling_edge; if ((rising_edge && !info->assert_falling_edge) || (!rising_edge && info->assert_falling_edge)) - pps_event(info->pps, &ts, PPS_CAPTUREASSERT, data); + pps_event(info->pps, &info->ts, PPS_CAPTUREASSERT, data); else if (info->capture_clear && ((rising_edge && info->assert_falling_edge) || (!rising_edge && !info->assert_falling_edge))) - pps_event(info->pps, &ts, PPS_CAPTURECLEAR, data); + pps_event(info->pps, &info->ts, PPS_CAPTURECLEAR, data); else dev_warn_ratelimited(&info->pps->dev, "IRQ did not trigger any PPS event\n"); @@ -210,8 +221,10 @@ static int pps_gpio_probe(struct platfor } /* register IRQ interrupt handler */ - ret = request_irq(data->irq, pps_gpio_irq_handler, - get_irqf_trigger_flags(data), data->info.name, data); + ret = request_threaded_irq(data->irq, + pps_gpio_irq_hardirq, pps_gpio_irq_thread, + get_irqf_trigger_flags(data) | IRQF_ONESHOT, + data->info.name, data); if (ret) { pps_unregister_source(data->pps); dev_err(dev, "failed to acquire IRQ %d\n", data->irq); _ Patches currently in -mm which might be from by@by-online.de are pps-pps-gpio-split-irq-handler-into-hardirq-timestamper-threaded-handler.patch