From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.domeneshop.no (smtp.domeneshop.no [194.63.252.55]) (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 91F8D5A65 for ; Sat, 10 Sep 2022 15:34:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=tronnes.org ; s=ds202112; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=Z+umsEgE+0BVdH31f6mmvIugV/Oo08OxjxooJr5Ldk0=; b=oOkKlFJg/widSzLx1kmtByViA7 iOPPJVXzhj9kBu4SsHbdIuC8ZvEUEWVuF7wtWK9NY1wDz3/5meiB92klu0LVN4Bm3K6+oo2Rbflxi xuhDbB9wgCuLMFKmNs4ZX3jsa8mX2XqIiqnuyGGBl4H6OSaQkIj1E6xZyyLBmYZurLWb31WizyZN+ O1jWvr/yubX+SzsqQLAKgCgR+wLUiayc0HOm6lizgh1Gaac2vu0rqaQKPtH1p4tEG0/zz8AByiMgj D4a4FsKWEWTK3jJgeBqj7gHvccozD0WQKEeJ7+NlQMxDBWJ/bcK/RIwj9La/k/u+OIFQRI7btv70F 1Ec0jrnA==; Received: from [2a01:799:961:d200:4519:292a:25da:963a] (port=63245) by smtp.domeneshop.no with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1oX2Uo-0006Kf-1D; Sat, 10 Sep 2022 17:34:14 +0200 Message-ID: <03d5a161-9bc9-3d04-acda-2e5ca5a19d71@tronnes.org> Date: Sat, 10 Sep 2022 17:34:04 +0200 Precedence: bulk X-Mailing-List: linux-sunxi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.13.0 Subject: Re: [PATCH v2 00/41] drm: Analog TV Improvements To: Stefan Wahren , Maxime Ripard , Dom Cobley Cc: Ben Skeggs , David Airlie , Chen-Yu Tsai , Thomas Zimmermann , Jani Nikula , Lyude Paul , Philipp Zabel , Maarten Lankhorst , Rodrigo Vivi , Tvrtko Ursulin , Jernej Skrabec , Samuel Holland , Karol Herbst , Emma Anholt , Daniel Vetter , Joonas Lahtinen , Hans de Goede , linux-arm-kernel@lists.infradead.org, Phil Elwell , intel-gfx@lists.freedesktop.org, Dave Stevenson , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, nouveau@lists.freedesktop.org, linux-sunxi@lists.linux.dev, Mateusz Kwiatkowski , Geert Uytterhoeven References: <20220728-rpi-analog-tv-properties-v2-0-459522d653a7@cerno.tech> <24e09a29-6d04-3b1e-63ce-cd3c31d350e2@tronnes.org> <020d44e6-884b-a817-8265-3461638cac71@tronnes.org> <20220905145729.ln675jko3aw6sgzs@houat> <965de5c0-bc6a-7210-c946-b916ae2219fc@i2se.com> From: =?UTF-8?Q?Noralf_Tr=c3=b8nnes?= In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Den 07.09.2022 18.44, skrev Noralf Trønnes: > > > Den 07.09.2022 12.36, skrev Stefan Wahren: >> Hi Maxime, >> >> Am 05.09.22 um 16:57 schrieb Maxime Ripard: >>> On Fri, Sep 02, 2022 at 01:28:16PM +0200, Noralf Trønnes wrote: >>>> >>>> Den 01.09.2022 21.35, skrev Noralf Trønnes: >>>>> >>>>> I have finally found a workaround for my kernel hangs. >>>>> >>>>> Dom had a look at my kernel and found that the VideoCore was fine, and >>>>> he said this: >>>>> >>>>>> That suggests cause of lockup was on arm side rather than VC side. >>>>>> >>>>>> But it's hard to diagnose further. Once you've had a peripheral not >>>>>> respond, the AXI bus locks up and no further operations are possible. >>>>>> Usual causes of this are required clocks being stopped or domains >>>>>> disabled and then trying to access the hardware. >>>>>> >>>>> So when I got this on my 64-bit build: >>>>> >>>>> [  166.702171] SError Interrupt on CPU1, code 0x00000000bf000002 -- >>>>> SError >>>>> [  166.702187] CPU: 1 PID: 8 Comm: kworker/u8:0 Tainted: G        W >>>>>      5.19.0-rc6-00096-gba7973977976-dirty #1 >>>>> [  166.702200] Hardware name: Raspberry Pi 4 Model B Rev 1.1 (DT) >>>>> [  166.702206] Workqueue: events_freezable_power_ >>>>> thermal_zone_device_check >>>>> [  166.702231] pstate: 200000c5 (nzCv daIF -PAN -UAO -TCO -DIT -SSBS >>>>> BTYPE=--) >>>>> [  166.702242] pc : regmap_mmio_read32le+0x10/0x28 >>>>> [  166.702261] lr : regmap_mmio_read+0x44/0x70 >>>>> ... >>>>> [  166.702606]  bcm2711_get_temp+0x58/0xb0 [bcm2711_thermal] >>>>> >>>>> I wondered if that reg read was stalled due to a clock being stopped. >>>>> >>>>> Lo and behold, disabling runtime pm and keeping the vec clock running >>>>> all the time fixed it[1]. >>>>> >>>>> I don't know what the problem is, but at least I can now test this >>>>> patchset. >>>>> >>>>> [1] https://gist.github.com/notro/23b984e7fa05cfbda2db50a421cac065 >>>>> >>>> It turns out I didn't have to disable runtime pm: >>>> https://gist.github.com/notro/0adcfcb12460b54e54458afe11dc8ea2 >>> If the bcm2711_thermal IP needs that clock to be enabled, it should grab >>> a reference itself, but it looks like even the device tree binding >>> doesn't ask for one. >> The missing clock in the device tree binding is expected, because >> despite of the code there is not much information about the BCM2711 >> clock tree. But i'm skeptical that the AVS IP actually needs the VEC >> clock, i think it's more likely that the VEC clock parent is changed and >> that cause this issue. I could take care of the bcm2711 binding & driver >> if i know which clock is really necessary. > > Seems you're right, keeping the parent always enabled is enough: > > clk_prepare_enable(clk_get_parent(vec->clock)); // pllc_per > > I tried enabling just the grandparent clock as well, but that didn't help. > > Without the clock hack it seems the hang occurs when switching between > NTSC and PAL, at most I've been able to do that 4-5 times before it hangs. > > For a while it looked like fbdev/fbcon had a play in this, but then I > realised that it just gave me a NTSC mode to start from and to go back > to when qutting modetest. > I've looked some more into this problem and I see that downstream is using a firmware clock for vec: clk: Move vec clock to clk-raspberrypi https://github.com/raspberrypi/linux/pull/4639 If I do the same my problem goes away. It's interesting to note that on downstream 5.10.103-v7l+ #1530, pllc_per is enabled even if tvout is not enabled: $ sudo cat /sys/kernel/debug/clk/pllc_per/regdump cm = 0x00000000 a2w = 0x00000004 (disable bit(8) is not set) It's when mainline vc4_vec disables this vec parent clock that the crash occurs. Sidenote: Another downstream fw clock change with a vec reference[1]: Another issue not related to the clock crash problem: I assumed that unloading the vc4 module would release the clocks, but this didn't happen. When I looked at it I remembered that there's a catch in the DRM unplug machinery when it comes to unloading a driver and the DRM disable hooks. static void vc4_drm_unbind(struct device *dev) { struct drm_device *drm = dev_get_drvdata(dev); drm_dev_unplug(drm); drm_atomic_helper_shutdown(drm); } Here the drm_device is first marked as unplugged and then the pipeline is disabled. Since vc4_vec_encoder_disable() is protected by drm_dev_enter() the VEC is not disabled, clocks are not released and PM is left on. In the drivers that I have written where the hardware is not expected to have gone away on device unbind (SPI), I've just left out the drm_dev_enter() check in the disable hook. Noralf. [1] https://github.com/raspberrypi/linux/pull/4706