From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-04.galae.net (smtpout-04.galae.net [185.171.202.116]) (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 EF4282C11E9 for ; Wed, 28 Jan 2026 10:02:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.171.202.116 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769594551; cv=none; b=bIIocPDzbJVgMndGrWCu06CqSETLkUNVZrtVmBZlHvBOG26UC6oVT2QmqS2WFTmHG+gYYBKtw/HMop9C5DT2SUyyDzBHn9ojSJ47cFKpkEKhNybBzB3qV7vmYQv5dsOwC+us3vvP1ce6hfTYiDvHrFhjMhlkS/KQ46QWsjM4HJM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769594551; c=relaxed/simple; bh=F72nBXVKIDY5tpWLPUxBk5sHSnJn/wGfp9bj9IxOdwQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=fry8HQKU9OxgYBTBB7Ly+hRmZg2nBfMYBPrgaqaHlWwH1pXSMdPC9lWcZCcADyiSXKDonUu/HswI7MZK2AHIaCY3FhBRnWZ/OAb5T6Uz+Bq+hjM8yCzg1MC83BAXoAGkILk1Gf6SykcI5R2gZDGe3CCJGbWo+P8o0VC+ezNcX/o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=sjd96eby; arc=none smtp.client-ip=185.171.202.116 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="sjd96eby" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-04.galae.net (Postfix) with ESMTPS id C2D29C211E3; Wed, 28 Jan 2026 10:02:23 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 49F6E6071A; Wed, 28 Jan 2026 10:02:21 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 17E2C119A8805; Wed, 28 Jan 2026 11:02:13 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1769594538; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:content-language:in-reply-to:references; bh=jl/qUj03yO9xDW1xqUwBwXsZCnYBNJNRMPOW11zOe6Y=; b=sjd96ebyrvCGdPERJq6YfDm4tCFtKy+a7g8m54wbglfV7iboWOEwY5SJmSfnInyV4QPBlY LzDO5YFZ1j+mGCmYTk8GCQjQy9wpAUCtaXmm2EfayCmHll9JgibdqvDTgkHpGSQQrFLAEO CdvX1tkRhD9D9Zhg56BJ+XIv+QG0dBdqwlApnNO4alZVBO14eCXTwOiZ9FI37MWwCfDwBc hU1eeKF1lmnHZw4ow541st0frBdOYlTx4xsD1wZe2NjwlKoRSebHvWKqYoGARtcvb2PH77 wupAyD/u1Edg7tK/FRyQjMJiFOJ/RriyV7US/aExvrfKYduY1o7agjt9LkGX7A== Message-ID: Date: Wed, 28 Jan 2026 11:02:13 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net] net: phy: micrel: fix clk warning when removing the driver To: Wei Fang , "andrew@lunn.ch" , "hkallweit1@gmail.com" , "linux@armlinux.org.uk" , "davem@davemloft.net" , "edumazet@google.com" , "kuba@kernel.org" , "pabeni@redhat.com" , "florian.fainelli@broadcom.com" Cc: "imx@lists.linux.dev" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <20260126081544.983517-1-wei.fang@nxp.com> <13f1599a-afd7-4350-a395-83c57ab91f18@bootlin.com> From: Maxime Chevallier Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Last-TLS-Session-Version: TLSv1.3 On 28/01/2026 10:36, Wei Fang wrote: >> On 26/01/2026 09:15, Wei Fang wrote: >>> Since the commit 25c6a5ab151f ("net: phy: micrel: Dynamically control >>> external clock of KSZ PHY"), the clock of Micrel PHY has been enabled >>> by phy_driver::resume() and disabled by phy_driver::suspend(). However, >>> devm_clk_get_optional_enabled() is used in kszphy_probe(), so the clock >>> will automatically be disabled when the device is unbound from the bus. >>> Therefore, this could cause the clock to be disabled twice, resulting >>> in clk driver warnings. >>> >>> For example, this issue can be reproduced on i.MX6ULL platform, and we >>> can see the following logs when removing the FEC MAC drivers. >>> >>> $ echo 2188000.ethernet > /sys/bus/platform/drivers/fec/unbind >>> $ echo 20b4000.ethernet > /sys/bus/platform/drivers/fec/unbind >>> [ 109.758207] ------------[ cut here ]------------ >>> [ 109.758240] WARNING: drivers/clk/clk.c:1188 at >> clk_core_disable+0xb4/0xd0, CPU#0: sh/639 >>> [ 109.771011] enet2_ref already disabled >>> [ 109.793359] Call trace: >>> [ 109.822006] clk_core_disable from clk_disable+0x28/0x34 >>> [ 109.827340] clk_disable from clk_disable_unprepare+0xc/0x18 >>> [ 109.833029] clk_disable_unprepare from devm_clk_release+0x1c/0x28 >>> [ 109.839241] devm_clk_release from devres_release_all+0x98/0x100 >>> [ 109.845278] devres_release_all from device_unbind_cleanup+0xc/0x70 >>> [ 109.851571] device_unbind_cleanup from >> device_release_driver_internal+0x1a4/0x1f4 >>> [ 109.859170] device_release_driver_internal from >> bus_remove_device+0xbc/0xe4 >>> [ 109.866243] bus_remove_device from device_del+0x140/0x458 >>> [ 109.871757] device_del from phy_mdio_device_remove+0xc/0x24 >>> [ 109.877452] phy_mdio_device_remove from >> mdiobus_unregister+0x40/0xac >>> [ 109.883918] mdiobus_unregister from >> fec_enet_mii_remove+0x40/0x78 >>> [ 109.890125] fec_enet_mii_remove from fec_drv_remove+0x4c/0x158 >>> [ 109.896076] fec_drv_remove from >> device_release_driver_internal+0x17c/0x1f4 >>> [ 109.962748] WARNING: drivers/clk/clk.c:1047 at >> clk_core_unprepare+0xfc/0x13c, CPU#0: sh/639 >>> [ 109.975805] enet2_ref already unprepared >>> [ 110.002866] Call trace: >>> [ 110.031758] clk_core_unprepare from clk_unprepare+0x24/0x2c >>> [ 110.037440] clk_unprepare from devm_clk_release+0x1c/0x28 >>> [ 110.042957] devm_clk_release from devres_release_all+0x98/0x100 >>> [ 110.048989] devres_release_all from device_unbind_cleanup+0xc/0x70 >>> [ 110.055280] device_unbind_cleanup from >> device_release_driver_internal+0x1a4/0x1f4 >>> [ 110.062877] device_release_driver_internal from >> bus_remove_device+0xbc/0xe4 >>> [ 110.069950] bus_remove_device from device_del+0x140/0x458 >>> [ 110.075469] device_del from phy_mdio_device_remove+0xc/0x24 >>> [ 110.081165] phy_mdio_device_remove from >> mdiobus_unregister+0x40/0xac >>> [ 110.087632] mdiobus_unregister from >> fec_enet_mii_remove+0x40/0x78 >>> [ 110.093836] fec_enet_mii_remove from fec_drv_remove+0x4c/0x158 >>> [ 110.099782] fec_drv_remove from >> device_release_driver_internal+0x17c/0x1f4 >>> >>> After analyzing the process of removing the FEC driver, as shown below, >>> it can be seen that the clock was disabled twice by the PHY driver. >>> >>> fec_drv_remove() >>> --> fec_enet_close() >>> --> phy_stop() >>> --> phy_suspend() >>> --> kszphy_suspend() #1 The clock is disabled >>> --> fec_enet_mii_remove() >>> --> mdiobus_unregister() >>> --> phy_mdio_device_remove() >>> --> device_del() >>> --> devm_clk_release() #2 The clock is disabled again >>> >>> Therefore, devm_clk_get_optional() is used to fix the above issue. And >>> to avoid the issue mentioned by the commit 985329462723 ("net: phy: >>> micrel: use devm_clk_get_optional_enabled for the rmii-ref clock"), the >>> clock is enabled by clk_prepare_enable() to get the correct clock rate. >>> >>> Fixes: 25c6a5ab151f ("net: phy: micrel: Dynamically control external clock of >> KSZ PHY") >>> Signed-off-by: Wei Fang >> >> This should fix the issue indeed. The dance of enabling/disabling then >> re-enabling at resume() again feels odd, but at least it's balanced. >> >> We may be able to avoid that entirely by dealing with the ref_mii_clk >> selection only in the .resume() path, as it's also called no long after >> config_init(). That would mean reading the clock rate in >> kszphy_config_reset(), then performing the kszphy_rmii_clk_sel() >> accordingly. >> > > It seems rather strange to get the clock rate every time the .resume() > is called. Otherwise, we would need to add some additional logic to > kszphy_rmii_clk_sel() to ensure that the clock rate is only obtained > once. IMO, it would be more reasonable to only get the clock rate in > the .probe() during the lifetime of the PHY driver. > > Furthermore, this seems to break the previous logic: when the clock > rate is incorrect, the .probe() will return an error, meaning the PHY > driver will not be loaded. > Makes sense to validate it early indeed :) All in all, this seems ok then. Maxime