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 5A7A3426D0A for ; Mon, 14 Sep 2026 09:22:47 +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=1789377769; cv=none; b=rB7zyOAJilkMfj42UDdImBQLn5R30u5uI158mAAmxQSn8nGxyZc5YZ6rLP2M6zquI6sBQNsT9pRa0NzZN6nuWs4ua8XxweYGUjjyGQNi7imLww/FuZjmhsNIXnasvYKDMB40kWica/pM4tKhQNSgq70P223B0MOq5eVZvx37cCM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789377769; c=relaxed/simple; bh=73QlnaQCsgvzVtuZ6QGUlkNWbrbjwtABy1D5uYWfio0=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=RTT8YAVnpnYe8j0ouhm3Gzc+lBTX4Gwwc0tHEW6iXeF7E+YXlQ9LF3nbN+1jUSzPYOoQ7NoeLUIJb0/W1m12YMFZ601zY46g+6woCNm5fP8iZljgKCEFKrRJWOBXhuncoveneNRGJVq/sD7QLi//CysEbtzJhDeLGVW6FZTFlA0= 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=ff098847; 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="ff098847" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1789377765; bh=73QlnaQCsgvzVtuZ6QGUlkNWbrbjwtABy1D5uYWfio0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=ff098847j/8HbpgD0osP+HPAStE6yHiEhULC7sg5g3vg5GfaHoDsAwWNwjF1e2s5j pdv+LDFs/wkcEtV+8n0EdYdFUWC3QxTVm9OErLgm8HRHxyD1mHpzY0Qd6LqtZxkXR+ f3SP8Dq9rlWufRWBEyRuWV/AMvVsA6uS5OJNZaZtGo7OxUXYCIfaVRJYD0Gg4x730t e9Jp/A3JXk7wKXxBMQkloQnNpmYfIDhTQzfT01f29ycg9hpDOTz1FrC/1wPpxTgFU6 1pCxDe+a/AmVK1L41Rg6ELqYpMFDWmBApSPg8uuIPLthuFBn+UmA45UWICeOnI6Eb7 q5t/IJodMfn+g== Received: from fedora-21.home (unknown [100.64.0.11]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange secp256r1 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by bali.collaboradmins.com (Postfix) with ESMTPSA id 8248817E020C; Mon, 14 Sep 2026 11:22:44 +0200 (CEST) Date: Mon, 14 Sep 2026 11:22:37 +0200 From: Boris Brezillon To: =?UTF-8?B?QWRyacOhbg==?= Larumbe Cc: Rob Herring , Steven Price , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Faith Ekstrand , "Marty E. Plummer" , Tomeu Vizoso , Eric Anholt , Alyssa Rosenzweig , Robin Murphy , Philipp Zabel , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Collabora Kernel Team , Neil Armstrong Subject: Re: [PATCH v9 06/16] drm/panfrost: Fix PM refcnt and autosuspend issues at device probe/remove Message-ID: <20260914112237.70dedb9c@fedora-21.home> In-Reply-To: <20260912-claude-fixes-v9-6-e588feaa61ef@collabora.com> References: <20260912-claude-fixes-v9-0-e588feaa61ef@collabora.com> <20260912-claude-fixes-v9-6-e588feaa61ef@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 Sat, 12 Sep 2026 00:28:07 +0100 Adri=C3=A1n Larumbe wrote: > During device probe(), failure to do a PM get() will leave the usage_count > set to 0, which is the value assigned at device creation time. That means > when the autosuspend delay expires, runtime suspend callback won't be > invoked, so the device will remain powered on forever. >=20 > On top of that, failure to call PM put() during device unplug means > Panfrost device's PM usage_count increases monotonically for every new > module reload. >=20 > The outcome of both of the above meant that: >=20 > - Devfreq OPP transition notifications would be printed all the time, > even when no jobs are being submitted. This quickly fills the kernel > ring buffer with junk. > - Because MMU interrupts are only enabled when the device is reset, > the very first job targeting the tiler heap BO after device probe() > would always time out, since the driver's PM runtime resume callback > would not be invoked. >=20 > To fix the above: > - Manually adjust the PM refcnt at device probe and removal time. > - Ensure pm_runtime_dont_use_autosuspend is called in the wind-down path. > - Call pm_runtime_put_autosuspend() when device is ready to accept jobs > - Move pm_runtime_set_suspended() before panfrost_device_fini() so that > resource unwinding happens in the opposite order as initialisation. >=20 > Signed-off-by: Adri=C3=A1n Larumbe > Fixes: 635430797d3f ("drm/panfrost: Rework runtime PM initialization") > Fixes: 876b15d2c88d ("drm/panfrost: Fix module unload") > --- > drivers/gpu/drm/panfrost/panfrost_drv.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) >=20 > diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/pa= nfrost/panfrost_drv.c > index 55fc22e8d4d4..a3eff77add55 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_drv.c > +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c > @@ -854,6 +854,7 @@ static int panfrost_probe(struct platform_device *pde= v) > =20 > pm_runtime_set_active(pfdev->base.dev); > pm_runtime_mark_last_busy(pfdev->base.dev); > + pm_runtime_get_noresume(pfdev->base.dev); > pm_runtime_enable(pfdev->base.dev); > pm_runtime_set_autosuspend_delay(pfdev->base.dev, 50); /* ~3 frames */ > pm_runtime_use_autosuspend(pfdev->base.dev); > @@ -866,13 +867,16 @@ static int panfrost_probe(struct platform_device *p= dev) > if (err < 0) > goto err_out1; > =20 > + pm_runtime_put_autosuspend(pfdev->base.dev); > =20 > return 0; > =20 > err_out1: > + pm_runtime_dont_use_autosuspend(pfdev->base.dev); > pm_runtime_disable(pfdev->base.dev); > - panfrost_device_fini(pfdev); > + pm_runtime_put_noidle(pfdev->base.dev); > pm_runtime_set_suspended(pfdev->base.dev); > + panfrost_device_fini(pfdev); Not an issue per-se, because put_noidle() is a NOP, but I think it'd be easier to reason about with this order: pm_runtime_dont_use_autosuspend(pfdev->base.dev); pm_runtime_disable(pfdev->base.dev); panfrost_device_fini(pfdev); pm_runtime_set_suspended(pfdev->base.dev); pm_runtime_put_noidle(pfdev->base.dev); This makes it clear that panfrost_device_fini() assumes the device is resumed when it's called and suspended when it returns. > err_out0: > return err; > } > @@ -884,9 +888,11 @@ static void panfrost_remove(struct platform_device *= pdev) > drm_dev_unregister(&pfdev->base); > =20 > pm_runtime_get_sync(pfdev->base.dev); > + pm_runtime_dont_use_autosuspend(pfdev->base.dev); > + pm_runtime_put_noidle(pfdev->base.dev); > pm_runtime_disable(pfdev->base.dev); Let's keep the order consistent with the probe path: pm_runtime_dont_use_autosuspend(pfdev->base.dev); pm_runtime_disable(pfdev->base.dev); panfrost_device_fini(pfdev); pm_runtime_set_suspended(pfdev->base.dev); pm_runtime_put_noidle(pfdev->base.dev); I also think this deserves comments to explain the noresume/noidle dance (device_init/fini take care of clks internally, and when they return the device is resumed/suspended, so all we have to is update the state, and acquire a ref). > - panfrost_device_fini(pfdev); > pm_runtime_set_suspended(pfdev->base.dev); > + panfrost_device_fini(pfdev); > } > =20 > static ssize_t profiling_show(struct device *dev, >=20