From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0C546EB64DA for ; Tue, 4 Jul 2023 06:58:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=hi36o5h2UgmBCCPDgqXe5OOkZPotAilxaG+rJBSWDoo=; b=Ap7LfKv2ZsCleq F8eQoE1Ge3drokhyWEkMTQKt9PzcakDwvrPL+NL1KEPxo1G1vBdPXCOoTElzZDF25x6iBwGOEzWNv KpOjJd9ajCXBMpKNbatXPilBZuXpNGVhkTfSQ4mchmezFriOKNFwzSdx2VJlQ//AGR24guYkY9Tfu PZXl2qXjrYTS+itKgG1ses8Mv5znVZULBet49pcNa22ei1fithpOM1tf2cNh/eNvUnyZciApchxx3 ZPlcymaZ+yDLgUi/2o7mgN2squlBJuz7ewogubzibv48mScVAsEtdOmqEOteOelSyoZT1v19xAnzU ZJ0vWxhg7LKGkRyecGMw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qGZza-00CNfz-2T; Tue, 04 Jul 2023 06:58:30 +0000 Received: from mx1.tq-group.com ([93.104.207.81]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qGZzW-00CNf0-0l for linux-arm-kernel@lists.infradead.org; Tue, 04 Jul 2023 06:58:28 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tq-group.com; i=@tq-group.com; q=dns/txt; s=key1; t=1688453906; x=1719989906; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=3mKvlJpyqrm8KLFesfDVIKrJmLCF5r0paQZpEMj5YGA=; b=EGx7mdsuCmq8Sdq+8xLAj0yyfp83ACZV9BMQSj8DMeLdcwTM193TS0iY jDzeajARqFJS4f3tAlUCiv7YyHZuIw0DBjGxjf81ATDEx7VJjo+9GsuOA qWZBIqI3KRLPQ4tJElOdyZ88ALX3LediKqSrvQJJPJyp8ZwmzKYIRrsO7 MnxvJmPA10aLKCldivA9mGLxaQEeh+2i15QSwJcs3QLmwD+tvuh8Om+6n sc9bS1cr6HIFN+RUpVwNrbYvwv3/Gz5TZNrKJB3K/M99vnHneM/z6zXRs 2GUkNtMgJNHemv2BZXk0enBBLngVKddIadUqfN2eCPNopPrx07a9BSec+ w==; X-IronPort-AV: E=Sophos;i="6.01,179,1684792800"; d="scan'208";a="31737652" Received: from vtuxmail01.tq-net.de ([10.115.0.20]) by mx1.tq-group.com with ESMTP; 04 Jul 2023 08:58:21 +0200 Received: from steina-w.localnet (unknown [10.123.53.21]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by vtuxmail01.tq-net.de (Postfix) with ESMTPSA id 33BCB280087; Tue, 4 Jul 2023 08:58:21 +0200 (CEST) From: Alexander Stein To: NXP Linux Team , "A. Sverdlin" Cc: Alexander Sverdlin , Dong Aisheng , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5] i2c: lpi2c: cache peripheral clock rate Date: Tue, 04 Jul 2023 08:58:20 +0200 Message-ID: <12242804.O9o76ZdvQC@steina-w> Organization: TQ-Systems GmbH In-Reply-To: <20230628115824.3470880-1-alexander.sverdlin@siemens.com> References: <20230628115824.3470880-1-alexander.sverdlin@siemens.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230703_235826_701088_579784B5 X-CRM114-Status: GOOD ( 28.22 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Am Mittwoch, 28. Juni 2023, 13:58:22 CEST schrieb A. Sverdlin: > From: Alexander Sverdlin > = > One of the reasons to do it is to save some CPU cycles on cpu_freq_get() > under mutex. The second reason if the (false-positive) lockdep splat caus= ed > by the recursive feature of the "prepare_lock" (one clock instance is I2C > peripheral clock and another is pcf85063 RTC as clock provider): > = > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D > WARNING: possible circular locking dependency detected > 5.15.71+... #1 Tainted: G O > ------------------------------------------------------ > .../2332 is trying to acquire lock: > ffff8000096cae08 (prepare_lock){+.+.}-{3:3}, at: clk_prepare_lock+0x50/0x= b0 > = > but task is already holding lock: > ffff000011021100 (i2c_register_adapter){+.+.}-{3:3}, at: > i2c_adapter_lock_bus+0x2c/0x3c > = > which lock already depends on the new lock. > = > the existing dependency chain (in reverse order) is: > = > -> #2 (i2c_register_adapter){+.+.}-{3:3}: > lock_acquire+0x68/0x8c > rt_mutex_lock_nested+0x88/0xe0 > i2c_adapter_lock_bus+0x2c/0x3c > i2c_transfer+0x58/0x130 > regmap_i2c_read+0x64/0xb0 > _regmap_raw_read+0x114/0x440 > _regmap_bus_read+0x4c/0x84 > _regmap_read+0x6c/0x270 > regmap_read+0x54/0x80 > pcf85063_probe+0xec/0x4cc > i2c_device_probe+0x10c/0x350 > really_probe+0xc4/0x470 > __driver_probe_device+0x11c/0x190 > driver_probe_device+0x48/0x110 > __device_attach_driver+0xc4/0x160 > bus_for_each_drv+0x80/0xe0 > __device_attach+0xb0/0x1f0 > device_initial_probe+0x1c/0x2c > bus_probe_device+0xa4/0xb0 > device_add+0x398/0x8ac > device_register+0x28/0x40 > i2c_new_client_device+0x144/0x290 > of_i2c_register_devices+0x18c/0x230 > i2c_register_adapter+0x1dc/0x6b0 > __i2c_add_numbered_adapter+0x68/0xbc > i2c_add_adapter+0xb0/0xe0 > lpi2c_imx_probe+0x354/0x5e0 > platform_probe+0x70/0xec > really_probe+0xc4/0x470 > __driver_probe_device+0x11c/0x190 > driver_probe_device+0x48/0x110 > __device_attach_driver+0xc4/0x160 > bus_for_each_drv+0x80/0xe0 > __device_attach+0xb0/0x1f0 > device_initial_probe+0x1c/0x2c > bus_probe_device+0xa4/0xb0 > deferred_probe_work_func+0xa0/0xfc > process_one_work+0x2ac/0x6f4 > worker_thread+0x7c/0x47c > kthread+0x150/0x16c > ret_from_fork+0x10/0x20 > = > -> #1 (rtc_pcf85063:560:(&config->regmap)->lock){+.+.}-{3:3}: > lock_acquire+0x68/0x8c > __mutex_lock+0x9c/0x4d0 > mutex_lock_nested+0x48/0x5c > regmap_lock_mutex+0x1c/0x30 > regmap_read+0x44/0x80 > pcf85063_clkout_recalc_rate+0x34/0x80 > __clk_register+0x520/0x880 > devm_clk_register+0x64/0xc4 > pcf85063_probe+0x24c/0x4cc > i2c_device_probe+0x10c/0x350 > really_probe+0xc4/0x470 > __driver_probe_device+0x11c/0x190 > driver_probe_device+0x48/0x110 > __device_attach_driver+0xc4/0x160 > bus_for_each_drv+0x80/0xe0 > __device_attach+0xb0/0x1f0 > device_initial_probe+0x1c/0x2c > bus_probe_device+0xa4/0xb0 > device_add+0x398/0x8ac > device_register+0x28/0x40 > i2c_new_client_device+0x144/0x290 > of_i2c_register_devices+0x18c/0x230 > i2c_register_adapter+0x1dc/0x6b0 > __i2c_add_numbered_adapter+0x68/0xbc > i2c_add_adapter+0xb0/0xe0 > lpi2c_imx_probe+0x354/0x5e0 > platform_probe+0x70/0xec > really_probe+0xc4/0x470 > __driver_probe_device+0x11c/0x190 > driver_probe_device+0x48/0x110 > __device_attach_driver+0xc4/0x160 > bus_for_each_drv+0x80/0xe0 > __device_attach+0xb0/0x1f0 > device_initial_probe+0x1c/0x2c > bus_probe_device+0xa4/0xb0 > deferred_probe_work_func+0xa0/0xfc > process_one_work+0x2ac/0x6f4 > worker_thread+0x7c/0x47c > kthread+0x150/0x16c > ret_from_fork+0x10/0x20 > = > -> #0 (prepare_lock){+.+.}-{3:3}: > __lock_acquire+0x1298/0x20d0 > lock_acquire.part.0+0xf0/0x250 > lock_acquire+0x68/0x8c > __mutex_lock+0x9c/0x4d0 > mutex_lock_nested+0x48/0x5c > clk_prepare_lock+0x50/0xb0 > clk_get_rate+0x28/0x80 > lpi2c_imx_xfer+0xb0/0xa9c > __i2c_transfer+0x174/0xa80 > i2c_transfer+0x68/0x130 > regmap_i2c_read+0x64/0xb0 > _regmap_raw_read+0x114/0x440 > regmap_raw_read+0x19c/0x28c > regmap_bulk_read+0x1b8/0x244 > at24_read+0x14c/0x2c4 > nvmem_reg_read+0x2c/0x54 > bin_attr_nvmem_read+0x8c/0xbc > sysfs_kf_bin_read+0x74/0x94 > kernfs_fop_read_iter+0xb0/0x1d0 > new_sync_read+0xf0/0x184 > vfs_read+0x154/0x1f0 > ksys_read+0x70/0x100 > __arm64_sys_read+0x24/0x30 > invoke_syscall+0x50/0x120 > el0_svc_common.constprop.0+0x68/0x124 > do_el0_svc+0x30/0x9c > el0_svc+0x54/0x110 > el0t_64_sync_handler+0xa4/0x130 > el0t_64_sync+0x1a0/0x1a4 > = > other info that might help us debug this: > = > Chain exists of: > prepare_lock --> rtc_pcf85063:560:(&config->regmap)->lock --> > i2c_register_adapter > = > Possible unsafe locking scenario: > = > CPU0 CPU1 > ---- ---- > lock(i2c_register_adapter); > = > lock(rtc_pcf85063:560:(&config->regmap)->lock); lock(i2c_register_adapter= ); > lock(prepare_lock); > = > *** DEADLOCK *** > = > 4 locks held by .../2332: > #0: ffff0000146eb288 (&of->mutex){+.+.}-{3:3}, at: > kernfs_fop_read_iter+0x74/0x1d0 #1: ffff000010fe4400 > (kn->active#72){.+.+}-{0:0}, at: kernfs_fop_read_iter+0x7c/0x1d0 #2: > ffff0000110168e8 (&at24->lock){+.+.}-{3:3}, at: at24_read+0x8c/0x2c4 #3: > ffff000011021100 (i2c_register_adapter){+.+.}-{3:3}, at: > i2c_adapter_lock_bus+0x2c/0x3c > = > stack backtrace: > CPU: 1 PID: 2332 Comm: ... Tainted: G O 5.15.71+... #1 > Hardware name: ... (DT) > Call trace: > dump_backtrace+0x0/0x1d4 > show_stack+0x20/0x2c > dump_stack_lvl+0x8c/0xb8 > dump_stack+0x18/0x34 > print_circular_bug+0x1f8/0x200 > check_noncircular+0x130/0x144 > __lock_acquire+0x1298/0x20d0 > lock_acquire.part.0+0xf0/0x250 > lock_acquire+0x68/0x8c > __mutex_lock+0x9c/0x4d0 > mutex_lock_nested+0x48/0x5c > clk_prepare_lock+0x50/0xb0 > clk_get_rate+0x28/0x80 > lpi2c_imx_xfer+0xb0/0xa9c > __i2c_transfer+0x174/0xa80 > i2c_transfer+0x68/0x130 > regmap_i2c_read+0x64/0xb0 > _regmap_raw_read+0x114/0x440 > regmap_raw_read+0x19c/0x28c > regmap_bulk_read+0x1b8/0x244 > at24_read+0x14c/0x2c4 > nvmem_reg_read+0x2c/0x54 > bin_attr_nvmem_read+0x8c/0xbc > sysfs_kf_bin_read+0x74/0x94 > kernfs_fop_read_iter+0xb0/0x1d0 > new_sync_read+0xf0/0x184 > vfs_read+0x154/0x1f0 > ksys_read+0x70/0x100 > __arm64_sys_read+0x24/0x30 > invoke_syscall+0x50/0x120 > el0_svc_common.constprop.0+0x68/0x124 > do_el0_svc+0x30/0x9c > el0_svc+0x54/0x110 > el0t_64_sync_handler+0xa4/0x130 > el0t_64_sync+0x1a0/0x1a4 > = > Fixes: a55fa9d0e42e ("i2c: imx-lpi2c: add low power i2c bus driver") > Reviewed-by: Alexander Stein > Signed-off-by: Alexander Sverdlin > --- > Changelog: > v5: rebased onto Wolfram's i2c/for-next > v4: switched to atomic_t > included clk_rate_exclusive_get()/clk_rate_exclusive_put() > v3: fixed build error reported by kernel test robot The rebase still works as intended. Thanks and best regards, alexander > https://lore.kernel.org/oe-kbuild-all/202303102010.pAv56wKs-lkp@intel.com/ > v2: added clk_notifier as Alexander suggested > drivers/i2c/busses/i2c-imx-lpi2c.c | 47 +++++++++++++++++++++++++++--- > 1 file changed, 43 insertions(+), 4 deletions(-) > = > diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c > b/drivers/i2c/busses/i2c-imx-lpi2c.c index c3287c887c6f..02d376096707 > 100644 > --- a/drivers/i2c/busses/i2c-imx-lpi2c.c > +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c > @@ -5,6 +5,7 @@ > * Copyright 2016 Freescale Semiconductor, Inc. > */ > = > +#include > #include > #include > #include > @@ -100,6 +101,8 @@ struct lpi2c_imx_struct { > __u8 *rx_buf; > __u8 *tx_buf; > struct completion complete; > + struct notifier_block clk_change_nb; > + atomic_t rate_per; > unsigned int msglen; > unsigned int delivered; > unsigned int block_data; > @@ -198,25 +201,39 @@ static void lpi2c_imx_stop(struct lpi2c_imx_struct > *lpi2c_imx) } while (1); > } > = > +static int lpi2c_imx_clk_change_cb(struct notifier_block *nb, > + unsigned long action, void *data) > +{ > + struct clk_notifier_data *ndata =3D data; > + struct lpi2c_imx_struct *lpi2c_imx =3D container_of(nb, > + struct = lpi2c_imx_struct, > + = clk_change_nb); > + > + if (action & POST_RATE_CHANGE) > + atomic_set(&lpi2c_imx->rate_per, ndata->new_rate); > + > + return NOTIFY_OK; > +} > + > /* CLKLO =3D I2C_CLK_RATIO * CLKHI, SETHOLD =3D CLKHI, DATAVD =3D CLKHI/= 2 */ > static int lpi2c_imx_config(struct lpi2c_imx_struct *lpi2c_imx) > { > u8 prescale, filt, sethold, datavd; > - unsigned int clk_rate, clk_cycle, clkhi, clklo; > + unsigned int clk_cycle, clkhi, clklo; > enum lpi2c_imx_pincfg pincfg; > unsigned int temp; > = > lpi2c_imx_set_mode(lpi2c_imx); > = > - clk_rate =3D clk_get_rate(lpi2c_imx->clks[0].clk); > if (lpi2c_imx->mode =3D=3D HS || lpi2c_imx->mode =3D=3D ULTRA_FAST) > filt =3D 0; > else > filt =3D 2; > = > for (prescale =3D 0; prescale <=3D 7; prescale++) { > - clk_cycle =3D clk_rate / ((1 << prescale) * lpi2c_imx- >bitrate) > - - 3 - (filt >> 1); > + clk_cycle =3D atomic_read(&lpi2c_imx->rate_per) / > + ((1 << prescale) * lpi2c_imx->bitrate) - 3 - > + (filt >> 1); > clkhi =3D DIV_ROUND_UP(clk_cycle, I2C_CLK_RATIO + 1); > clklo =3D clk_cycle - clkhi; > if (clklo < 64) > @@ -594,6 +611,28 @@ static int lpi2c_imx_probe(struct platform_device > *pdev) if (ret) > return ret; > = > + lpi2c_imx->clk_change_nb.notifier_call =3D lpi2c_imx_clk_change_cb; > + ret =3D devm_clk_notifier_register(&pdev->dev, lpi2c_imx->clks[0].clk, > + &lpi2c_imx->clk_change_nb); > + if (ret) > + return dev_err_probe(&pdev->dev, ret, > + "can't register peripheral clock = notifier\n"); > + /* > + * Lock the clock rate to avoid rate change between clk_get_rate() = and > + * atomic_set() > + */ > + ret =3D clk_rate_exclusive_get(lpi2c_imx->clks[0].clk); > + if (ret) { > + dev_err(&pdev->dev, "can't lock I2C peripheral clock = rate\n"); > + return ret; > + } > + atomic_set(&lpi2c_imx->rate_per, clk_get_rate(lpi2c_imx- >clks[0].clk)); > + clk_rate_exclusive_put(lpi2c_imx->clks[0].clk); > + if (!atomic_read(&lpi2c_imx->rate_per)) { > + dev_err(&pdev->dev, "can't get I2C peripheral clock = rate\n"); > + return -EINVAL; > + } > + > pm_runtime_set_autosuspend_delay(&pdev->dev, I2C_PM_TIMEOUT); > pm_runtime_use_autosuspend(&pdev->dev); > pm_runtime_get_noresume(&pdev->dev); -- = TQ-Systems GmbH | M=FChlstra=DFe 2, Gut Delling | 82229 Seefeld, Germany Amtsgericht M=FCnchen, HRB 105018 Gesch=E4ftsf=FChrer: Detlef Schneider, R=FCdiger Stahl, Stefan Schneider http://www.tq-group.com/ _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel