From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) (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 00719356765 for ; Wed, 13 May 2026 08:09:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.251.105.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778659749; cv=none; b=u4Y0cBcC5FGjL/vRmq6vD5Yu07Bi3S0rENGxJoACRdVjCLy3dgSmwon4DX7aNDHMNkaHyNG3oABD63OCQ2F2wwXzifDncsYSEDhJgpm8TA9xkmsbuy24SjppqunmxRqmJ1xs/rS+L7RJNK2GVQZdleFpdAVchkefMvvFJi0saDE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778659749; c=relaxed/simple; bh=1HD83A4OZRnR0jOU/ml8g6QMXp0hWi547eD8+Be+NSw=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=boST40CE9F8LgUB45IFaurZxm2SUytlik72BgAZHRjSVeEtU3riSC0XruTEw1mYchS2lHf/jVoUTnGY/QJwgMa5y2SVWutbZHLxtqC29gk1+xdQbTzIipSOlCqQ5bmhc0vJFGPahgMdQ+8o1Ka9tAeL9V8CXNUcjkNJ5ke0mJkI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=M79WqQKP; arc=none smtp.client-ip=148.251.105.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="M79WqQKP" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1778659746; bh=1HD83A4OZRnR0jOU/ml8g6QMXp0hWi547eD8+Be+NSw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=M79WqQKPFH8pZWRRgFKieZqcob8DU2T9+KP/WE9s/p3FcN8s1KKHQw5UIJnJ2Wc/f +FH2JZM3nwQn31eMbUp7r8y+NmNK5hmJagR2b8+56uOIfoidVMADJE+8QT3uNrpwJN rqcbFe7T6lvSZdEXdbshGXL8/mxT3tIAK6G9fliVO5dB01nSlafVuHMdLFFwttU1HG 2kGNOQA9FZ3Bb6IH6rdRA6Yq/gjzXBBarOGyRkisCdtzi9dYHGbaSByLwNrzO+OyEN kAY+B5mS0yUbY3x3vHrumr30ZLs9QsWF9YN9z6SgqDLCbdEMwe5vcKoTVnq0F/aCYA d28UIllc/KX8g== Received: from fedora (unknown [100.64.0.11]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by bali.collaboradmins.com (Postfix) with ESMTPSA id D76FC17E0411; Wed, 13 May 2026 10:09:05 +0200 (CEST) Date: Wed, 13 May 2026 10:09:01 +0200 From: Boris Brezillon To: Chia-I Wu Cc: Steven Price , Liviu Dudau , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 04/11] drm/panthor: Extend the IRQ logic to allow fast/hard IRQ handlers Message-ID: <20260513100901.7b497929@fedora> In-Reply-To: References: <20260512-panthor-signal-from-irq-v2-0-95c614a739cb@collabora.com> <20260512-panthor-signal-from-irq-v2-4-95c614a739cb@collabora.com> Organization: Collabora X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Tue, 12 May 2026 12:11:08 -0700 Chia-I Wu wrote: > On Tue, May 12, 2026 at 4:54=E2=80=AFAM Boris Brezillon > wrote: > > > > All drivers except panthor signal their fences from their interrupt > > handler to minimize latency. We could do the same from the threaded > > handler, but the latency is still quite high in that case, so let's > > allow components to choose the context they want their IRQ handler > > to run in by exposing support for custom hard handlers. > > > > Reviewed-by: Liviu Dudau > > Reviewed-by: Steven Price > > Signed-off-by: Boris Brezillon > > --- > > drivers/gpu/drm/panthor/panthor_device.h | 11 ++++++++--- > > drivers/gpu/drm/panthor/panthor_fw.c | 1 + > > drivers/gpu/drm/panthor/panthor_gpu.c | 1 + > > drivers/gpu/drm/panthor/panthor_mmu.c | 1 + > > drivers/gpu/drm/panthor/panthor_pwr.c | 1 + > > 5 files changed, 12 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm= /panthor/panthor_device.h > > index 393fcda73d88..1aaf06df875b 100644 > > --- a/drivers/gpu/drm/panthor/panthor_device.h > > +++ b/drivers/gpu/drm/panthor/panthor_device.h > > @@ -672,6 +672,7 @@ static inline void panthor_irq_disable_events(struc= t panthor_irq *pirq, u32 mask > > static inline int > > panthor_irq_request(struct panthor_device *ptdev, struct panthor_irq *= pirq, > > int irq, u32 mask, void __iomem *iomem, const char = *name, > > + irqreturn_t (*raw_handler)(int, void *data), > > irqreturn_t (*threaded_handler)(int, void *data)) > > { > > const char *full_name; > > @@ -687,9 +688,13 @@ panthor_irq_request(struct panthor_device *ptdev, = struct panthor_irq *pirq, > > return -ENOMEM; > > > > panthor_irq_resume(pirq); > > - return devm_request_threaded_irq(ptdev->base.dev, irq, > > - panthor_irq_default_raw_handle= r, > > - threaded_handler, > > + > > + if (!threaded_handler) { > > + return devm_request_irq(ptdev->base.dev, irq, raw_handl= er, > > + IRQF_SHARED, full_name, pirq); > > + } =20 > devm_request_irq expands to devm_request_threaded_irq plus > IRQF_COND_ONESHOT. This appears redundant. I considered going for devm_request_threaded_irq(COND_ONESHOT), but I thought it was easier to reason about with a regular devm_request_irq() and an extra conditional since request_irq() is what people tend to use when they just have a hard handler (see [1], there's just one driver using it, and it's not even needed, because it's calling devm_request_irq() which adds this flag already) [1]https://elixir.bootlin.com/linux/v7.1-rc3/A/ident/IRQF_COND_ONESHOT