From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-03.galae.net (smtpout-03.galae.net [185.246.85.4]) (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 4C7C333B6EA for ; Fri, 17 Apr 2026 07:12:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.85.4 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776409937; cv=none; b=P1hiWcsOxe8eDuNd8wJdcMK+rmlYWazb5uOOIA3OAMPojbwkFImWrL1ffSYKpW6RLUQx5HAjLLw6bZdHZsIYVZB+zVdJS3oHan+2WznTWQqiArGTdOfVHZI/SNSItgyU9lYsRaM3ZzpDA6/8BkkC6K+J7FU0hgNgmzsmmPLZqgQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776409937; c=relaxed/simple; bh=Glf6m3+Hn5qEjZ9pj5xG2qpDwZac+wqxTio6gk3uADk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=cxI98cd0ecHpjZJgO7F2HgGHb4EYdxa3LgJdvMXKP6mwVhIAs8KqM47EKbOKw9uRuF+xllR/xJFHO89he/02ivWwvC8RhgPz9m77SDjufZZpFhycoKkEeznPPjtqsaWJIlIiSC0ZRDdPWFS64TZQy6uQ7qfiZfNpoX43PFS+n2M= 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=1qZcnU3F; arc=none smtp.client-ip=185.246.85.4 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="1qZcnU3F" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-03.galae.net (Postfix) with ESMTPS id 34E7F4E42A22; Fri, 17 Apr 2026 07:12:12 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id F3C4F60497; Fri, 17 Apr 2026 07:12:11 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 722BA10460946; Fri, 17 Apr 2026 09:12:00 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1776409931; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:content-language:in-reply-to:references; bh=IBacLVtaDD+BG01rHO7esJaLs6bAfvaO0ht5I5JeJ5A=; b=1qZcnU3FfRAWiLLrD9RvQE+7jqFv5N4MZhKuMyPs+eKII4hMWEOQgP0ZKUhr7VlDVEQXQl +r63/8FS6j054YsoP9zacr6dF9+AX2D2U1plFSffabMCcn6XjMmjJx7SQ85e4sNdjhb72a Fd1NB40UEspXATaGNYE+s3Sbumr8TA7M0bwLbfy9rvwJUXc6jqko3Lv8fZZCqAfZJOso11 s8NAL8gvRFvyKD6KhFa9IdrxzYweb+RhIi37cX+rrpborQe1GGPL0mILxVpNLoX8OBph6g +FFRILrQPDXucWndO02cJI09Jvzk1QsnCHlrf8mUsxi7P6Wo5x/wl6CC0P7rJQ== Message-ID: <680c384c-135f-44cd-a2cd-7e4fd0ec4bf7@bootlin.com> Date: Fri, 17 Apr 2026 09:11:59 +0200 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-next 5/6] net: stmmac: move PHY handling out of __stmmac_open()/release() To: "Russell King (Oracle)" , Alexander Stein Cc: Andrew Lunn , Heiner Kallweit , Alexandre Torgue , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , linux-arm-kernel@lists.infradead.org, linux-stm32@st-md-mailman.stormreply.com, Maxime Coquelin , netdev@vger.kernel.org, Paolo Abeni References: <5987484.DvuYhMxLoT@steina-w> <2410317.ElGaqSPkdT@steina-w> 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 Hi, On 16/04/2026 14:13, Russell King (Oracle) wrote: > On Thu, Apr 16, 2026 at 02:02:53PM +0200, Alexander Stein wrote: >> Hi Russel, >> >> Am Donnerstag, 16. April 2026, 12:49:25 CEST schrieb Russell King (Oracle): >>> On Thu, Apr 16, 2026 at 08:20:13AM +0200, Alexander Stein wrote: >>>> Am Mittwoch, 15. April 2026, 14:59:32 CEST schrieb Russell King (Oracle): >>>>> On Wed, Apr 15, 2026 at 08:08:40AM +0200, Alexander Stein wrote: >>>>>> Hi, >>>>>> >>>>>> Am Dienstag, 23. September 2025, 13:26:19 CEST schrieb Russell King (Oracle): >>>>>>> Move the PHY attachment/detachment from the network driver out of >>>>>>> __stmmac_open() and __stmmac_release() into stmmac_open() and >>>>>>> stmmac_release() where these actions will only happen when the >>>>>>> interface is administratively brought up or down. It does not make >>>>>>> sense to detach and re-attach the PHY during a change of MTU. >>>>>> >>>>>> Sorry for coming up now. But I recently noticed this commit breaks changing >>>>>> the MTU on i.MX8MP. Once I simply change the MTU I run into some DMA error: >>>>>> $ ip link set dev end1 mtu 1400 >>>>>> imx-dwmac 30bf0000.ethernet end1: Register MEM_TYPE_PAGE_POOL RxQ-0 >>>>>> imx-dwmac 30bf0000.ethernet end1: Register MEM_TYPE_PAGE_POOL RxQ-1 >>>>>> imx-dwmac 30bf0000.ethernet end1: Register MEM_TYPE_PAGE_POOL RxQ-2 >>>>>> imx-dwmac 30bf0000.ethernet end1: Register MEM_TYPE_PAGE_POOL RxQ-3 >>>>>> imx-dwmac 30bf0000.ethernet end1: Register MEM_TYPE_PAGE_POOL RxQ-4 >>>>>> imx-dwmac 30bf0000.ethernet end1: Link is Down >>>>>> imx-dwmac 30bf0000.ethernet end1: Failed to reset the dma >>>>>> imx-dwmac 30bf0000.ethernet end1: stmmac_hw_setup: DMA engine initialization failed >>>>> >>>>> This basically means that a clock is missing. Please provide more >>>>> information: >>>>> >>>>> - what kernel version are you using? >>>> >>>> Currently I am using v6.18.22. >>>> $ ethtool -i end1 >>>> driver: st_gmac >>>> version: 6.18.22 >>>> firmware-version: >>>> expansion-rom-version: >>>> bus-info: 30bf0000.ethernet >>>> supports-statistics: yes >>>> supports-test: no >>>> supports-eeprom-access: no >>>> supports-register-dump: yes >>>> supports-priv-flags: no >>>> >>>>> - has EEE been negotiated? >>>> >>>> No. It is marked as not supported >>>> >>>> $ ethtool --show-eee end1 >>>> EEE settings for end1: >>>> EEE status: not supported >>>> >>>>> - does the problem persist when EEE is disabled? >>>> >>>> As EEE is not supported the problem occurs even with EEE disabled. >>>> >>>>> - which PHY is attached to stmmac? >>>> >>>> It is a TI DP83867. >>>> >>>> imx-dwmac 30bf0000.ethernet eth1: PHY [stmmac-1:03] driver [TI DP83867] (irq=136) >>>> >>>>> - which PHY interface mode is being used to connect the PHY to stmmac? >>>> >>>> For this interface >>>>> phy-mode = "rgmii-id"; >>>> is set. >>>> >>>> In case it is helpful. My platform is arch/arm64/boot/dts/freescale/imx8mp-tqma8mpql-mba8mpxl.dts >>>> Thanks for assisting. If there a further questions, don't hesitate to ask. >>> >>> Thanks. >>> >>> So, as best I can determine at the moment, we end up with the following >>> sequence: >>> >>> stmmac_change_mtu() >>> __stmmac_release() >>> phylink_stop() >>> phy_stop() >>> phy->state = PHY_HALTED >>> _phy_state_machine() returns PHY_STATE_WORK_SUSPEND >>> _phy_state_machine_post_work() >>> phy_suspend() >>> genphy_suspend() >>> phy_set_bits(phydev, MII_BMCR, BMCR_PDOWN) >>> >>> With the DP83867, this causes most of the PHY to be powered down, thus >>> stopping the clocks, and this causes the stmmac reset to time out. >>> >>> Prior to this commit, we would have called phylink_disconnect_phy() >>> immediately after phylink_stop(), but I can see nothing that would >>> be affected by this change there (since that also calls >>> phy_suspend(), but as the PHY is already suspended, this becomes a >>> no-op.) >>> >>> However, __stmmac_open() would have called stmmac_init_phy(), which >>> would reattach the PHY. This would have called phy_init_hw(), >>> resetting the PHY, and phy_resume() which would ensure that the >>> PDOWN bit is clear - thus clocks would be running. >>> >>> As a hack, please can you try calling phylink_prepare_resume() >>> between the __stmmac_release() and __stmmac_open() in >>> stmmac_change_mtu(). This should resume the PHY, thus restoring the >>> clocks necessary for stmmac to reset. >> >> I tried the following patch. This works as you suspected. > > Brilliant, thanks for proving the theory why it broke. > > I'll have a think about the best way to solve this, because > phylink_prepare_resume() is supposed to be paired with phylink_resume() > and that isn't the case here. > > Please bear with me as my availability for looking at the kernel is > very unpredictable at present (family health issues.) FWIW I am able to reproduce this with imx8mp + ksz9131 I can give this a try as Russell isn't available. Maxime >