From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [78.32.30.218]) (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 5838A522F for ; Fri, 3 Jan 2025 09:16:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=78.32.30.218 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735895779; cv=none; b=Cudnebj39k3/nY7psY5HEzN5om7CnynFk2rlcz7xKyypKA8uRtUYcabs7WtbNq+6lOoKkWeHulc2X3WzKYgfb3q7eilPoyiOHGEzNOsLyOoUWD8Ni3R4NwWiMZEtt0/VRtD2jRqjDh50Aon60nlKKe/pZ5mshBBMT7/m5X4dqC4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735895779; c=relaxed/simple; bh=FUxttziUoVlO1t1o5GG7z/HrmLYZLxNctRkuBUXbHUs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=G2MYG7i/rfN3Vna2hpnL84AvIkVUB3G5kuUntUdS/oZipKrJrpa8hHE8YmHxIEZydhOcoD+cLTq4V9OiytMWJyR1R2HwK29ZZqBVjuHqDRddniEE9Z/b5UrU9ZLzsxfdI1Q1oFAbEZwXrjWpz3rQuNl7Vn0N630aHXJDDYsVnG8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk; spf=none smtp.mailfrom=armlinux.org.uk; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b=RK5zSwnx; arc=none smtp.client-ip=78.32.30.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="RK5zSwnx" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding: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=im15aEd2s/l2Puqf4hv4eGYyhlEhZU9l0dK6FNwO9Nw=; b=RK5zSwnxMPlw+jX3ebBKkF/p0m J3UxGFptAEf6AZRsMuJVHShDQ0rfFFvAJyM6nqfgI/ONz5t39pOTE+wpdRA+wziEKKNyFO7VxhQnG sqGEVA1ZtkzwCIsxBi8vRUNI11RZQEqmz2Wvzfn/SKu+EESQcUUJGpZ/KczGVoDhdA0SpN3WbnhIi GJID8bfy1ckbkLPNSgKrex7gkARqs6pmTfWYeMv6lwZP19XG7z3PFTaUQogkjCmpHDJqLCBS5fe9I EDrIWu+y0mAoWxO5KOiuAXnf/HhQ3LxbkMkqwd1LQ/XFjPcazifGpX1A1Y0AkvGKg81DwGN9vWz0K StUPLPPw==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:43592) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1tTdms-0002tK-1u; Fri, 03 Jan 2025 09:16:10 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.96) (envelope-from ) id 1tTdmr-0001C0-0X; Fri, 03 Jan 2025 09:16:09 +0000 Date: Fri, 3 Jan 2025 09:16:08 +0000 From: "Russell King (Oracle)" To: Richard Cochran Cc: Andrew Lunn , Heiner Kallweit , Marcin Wojtas , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Subject: Re: [PATCH net-next v3] net: mvpp2: tai: warn once if we fail to update our timestamp Message-ID: References: Precedence: bulk X-Mailing-List: netdev@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: Sender: Russell King (Oracle) On Fri, Jan 03, 2025 at 09:08:22AM +0000, Russell King (Oracle) wrote: > On Fri, Jan 03, 2025 at 12:43:56AM -0800, Richard Cochran wrote: > > On Thu, Jan 02, 2025 at 04:26:04PM +0000, Russell King (Oracle) wrote: > > > > > If we fail to read the clock, that will be because the hardware didn't > > > respond to our request to read it, which means the hardware broke in > > > some way. We could make mvpp22_tai_tstamp() fail and not provide > > > timestamps until we have successfully read the HW clock, but we would > > > still want to print a warning to explain why HW timestamps vanish. > > > > Sure, keep the warning, but also block time stamp delivery. > > > > > This is to catch a spurious failure that may only affects an occasoinal > > > attempt to read the HW PTP time. Currently, we would never know, > > > because the kernel is currently completely silent if that were to ever > > > happen. > > > > Is the failure spurious, or is the hardware broken and won't recover? > > I have absolutely no idea. I've never seen it happen. > > That's why I think going further than I have (and as you are suggesting) > is totally overkill. However, I should point out that I don't use PTP as a general rule for multiple reasons: 1. PTP is not as easy to deploy as NTP 2. Not everything has PTP support, whereas anything can support NTP. 3. PHY-based PTP support (where we need to read system time, read the PHY's PTP clock, re-read the system time and interpolate) seems to lead to a lot of noise making the stability of PHY based PTP inferior to NTP. Given this, I don't run PTP except for testing. Therefore, I think I'll drop this patch - it's clearly an approach that isn't wanted, and we'll just have silent *and* *wrong* hardware timestamps if this occurs. It seems it's better that users live in ignorance that their system has a problem. Thanks. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!