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Wed, 15 Oct 2025 23:41:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760571661; bh=7ZVXV77W0d05bk/8gSWIHFEpHIZsQ9H36dwcXGXNqro=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=h3+qsstLdZgrMKrIYjUUZJ3SpvHx3e+0csZghHbFI8vZbxfVK/12Zf+LUjJPRCy6Y pohFdY1HaBTMKdKHwutLvPO+PtHZB0hLTuyDrsWj/t7xUmSLjNJjHNT0I2ZIhtDR+u SNCw6SfnHhStgY9NVmZSJANBBGWFHP/KPTU71RmsroxJA8pWIrmyakAMOGhd0gRKGH 5GqgIy5P0cM1GHzA/SrSJOh3mhTWiqAJSqeKl1fAE45R/L4uXugJaIhti/x6XFG7Eu hCtg7UOPklPh/aO/TMXEk16iIYXrlwCfDfrjc+TAsQ/fv5Lsk8bp2yBVAQBsIKmwzi MA/Cqt6Jnyc+g== Date: Wed, 15 Oct 2025 18:40:59 -0500 From: Bjorn Helgaas To: Herve Codina Cc: Manivannan Sadhasivam , Lukas Wunner , Christian Zigotzky , Manivannan Sadhasivam , Ilpo =?utf-8?B?SsOkcnZpbmVu?= , "linux-pci@vger.kernel.org" , mad skateman , "R.T.Dickinson" , Christian Zigotzky , linuxppc-dev , hypexed@yahoo.com.au, Darren Stevens , "debian-powerpc@lists.debian.org" , Thomas Petazzoni Subject: Re: [PPC] Boot problems after the pci-v6.18-changes Message-ID: <20251015234059.GA961901@bhelgaas> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251015101304.3ec03e6b@bootlin.com> On Wed, Oct 15, 2025 at 10:13:04AM +0200, Herve Codina wrote: > ... > I also observed issues with the commit f3ac2ff14834 ("PCI/ASPM: Enable all > ClockPM and ASPM states for devicetree platforms") > > My system is an ARM board (Marvel Armada 3720 DDB) > https://elixir.bootlin.com/linux/v6.17.1/source/arch/arm64/boot/dts/marvell/armada-3720-db.dts > > I use an LAN966x PCI board > https://elixir.bootlin.com/linux/v6.17.1/source/drivers/misc/lan966x_pci.c > > Usually, when I did a ping using the PCI board, I have more or less the > following timings: > # ping 192.168.32.100 > PING 192.168.32.100 (192.168.32.100): 56 data bytes > 64 bytes from 192.168.32.100: seq=0 ttl=64 time=3.328 ms > 64 bytes from 192.168.32.100: seq=1 ttl=64 time=2.636 ms > 64 bytes from 192.168.32.100: seq=2 ttl=64 time=2.928 ms > 64 bytes from 192.168.32.100: seq=3 ttl=64 time=2.649 ms > > But with a vanilla v6.18-rc1 kernel, those timings become awful: > # ping 192.168.32.100 > PING 192.168.32.100 (192.168.32.100): 56 data bytes > 64 bytes from 192.168.32.100: seq=0 ttl=64 time=656.634 ms > 64 bytes from 192.168.32.100: seq=1 ttl=64 time=551.812 ms > 64 bytes from 192.168.32.100: seq=2 ttl=64 time=702.966 ms > 64 bytes from 192.168.32.100: seq=3 ttl=64 time=725.904 ms > > Reverting commit f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and > ASPM states for devicetree platforms") fixes my timing issues. We expect *some* performance impact from enabling ASPM, but this seems excessive. You should be able to control the ASPM settings for an individual device via sysfs: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/ABI/testing/sysfs-bus-pci?id=v6.17-rc1#n431 My guess is that L1.2 is enabled and the threshold values in the L1 PM Substates control registers are bogus. I don't know how to fix those, especially on a devicetree system. But it might be possible to fiddle with them using setpci (while ASPM is disabled). Not for the faint of heart. Bjorn