From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 0EBF033122A; Mon, 23 Feb 2026 17:36:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771868165; cv=none; b=KK3SVvL0eUCFPDqcZ/Q+0sDU4J5eiajQfiMsz/qQooVOrTaugbR1dlUW1pnoIj5pGAX+93hxQ+uROwt8Lgi1yPGOdhyrxvN8Dy/mygdhd4iyPqlV4kHp88ZGIMzSHXZNIrcNwsk9ylZLpthC02kUuleObGFwvmlspktvWYzVbLE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771868165; c=relaxed/simple; bh=UzeMxeCSwdtGeC1IFbmAYXxyY2BAf+KHGNJVeFD5WIQ=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=U8PLx32BsVHU21rCMonUtzwmfPHA60I5/amT1U6ryJfZHwWl3ox7JOpzl3B2pIzNYajw0RhrM8I9y6hGDVEZryrxGxsqwEREpRlZzJsgc2TgHEfEBYtI1GZJSssHvW09IxSoRSjKcksHfIee5FKt6hrEseu0OZ9xpnBeiVXHU5w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=c+3sf/GB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="c+3sf/GB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 92B57C19421; Mon, 23 Feb 2026 17:36:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771868164; bh=UzeMxeCSwdtGeC1IFbmAYXxyY2BAf+KHGNJVeFD5WIQ=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=c+3sf/GBD7hRLO03G3THuSoxWUyLuZiNVcGveNHfPj+Wg7mWr08BSf3vADCAJpoDj Kw/Tx3MLaOZe336eaSlX6oKa0KOpfE/0rCX4NHfeSFuoNKzrcuDHqIo1dCczPe2Fpy uvDEiAVlbsXu930mhWDOPtYIWlA1vPUm6o+xoPQagbVuggk78Yyq4yxji7tG/fDIVQ LIXsJqEB64fyUEqlv7+ApB5UubLYPjir2xGs0F8M5yMIcyQDZYpclVBasxaHJI0iTY AtFKVDq6E7fxAVmCqJMo4OUpsM5fwYFzavA5O36XwBTPETm3eZGi1P+n8cDg+EbPB3 FQZlc4vlX3VrA== Date: Mon, 23 Feb 2026 11:36:03 -0600 From: Bjorn Helgaas To: "Maciej W. Rozycki" Cc: Matthew W Carlis , ahuang12@lenovo.com, alok.a.tiwari@oracle.com, ashishk@purestorage.com, Bjorn Helgaas , guojinhui.liam@bytedance.com, Ilpo =?utf-8?B?SsOkcnZpbmVu?= , jiwei.sun.bj@qq.com, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Lukas Wunner , msaggi@purestorage.com, sconnor@purestorage.com, sunjw10@lenovo.com Subject: Re: [PATCH] PCI: Always lift 2.5GT/s restriction in PCIe failed link retraining Message-ID: <20260223173603.GA3698515@bhelgaas> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Feb 20, 2026 at 12:03:17PM +0000, Maciej W. Rozycki wrote: > On Thu, 19 Feb 2026, Bjorn Helgaas wrote: > > > > Can we reconsider my patch that restricts the link retrain mechanism > > > to the specific device that created the work-around? > > > https://lore.kernel.org/all/20250702052430.13716-1-mattc@purestorage.com/ > > > > I think we already at least potentially meddle with the link on every > > device, and it definitely makes me nervous. I would like it much > > better if it's possible to limit it to devices with known defects. > > > > I'll defer these for now and we can see if a consensus emerges. > > As I say it's logically impossible to figure out whether or not to > apply such a workaround where the culprit is the downstream device, > because until you've succeeded establishing a link you have no way > to figure out what the downstream device actually is. IIUC Matthew [1] and Alok [2] have reported issues that only happen when we run pcie_failed_link_retrain(). The issues seem to be with NVMe devices, but I don't see a root cause or a solution (other than skipping pcie_failed_link_retrain()). [1] https://lore.kernel.org/all/20250702052430.13716-2-mattc@purestorage.com/ [2] https://lore.kernel.org/all/c296df33-f9c0-42f7-8add-6966d89d00c4@oracle.com/