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linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, kernelnewbies X-BeenThere: kernelnewbies@kernelnewbies.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Learn about the Linux kernel List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: kernelnewbies-bounces@kernelnewbies.org T24gVHVlLCBGZWIgMjUsIDIwMjUgYXQgMDY6NDY6MDJQTSArMDUzMCwgTmF2ZWVuIEt1bWFyIFAg d3JvdGU6Cj4gT24gVHVlLCBGZWIgMjUsIDIwMjUgYXQgMToyNOKAr0FNIEJqb3JuIEhlbGdhYXMg PGhlbGdhYXNAa2VybmVsLm9yZz4gd3JvdGU6Cj4gPiBPbiBUdWUsIEZlYiAyNSwgMjAyNSBhdCAx MjoyOTowMEFNICswNTMwLCBOYXZlZW4gS3VtYXIgUCB3cm90ZToKPiA+ID4gT24gTW9uLCBGZWIg MjQsIDIwMjUgYXQgMTE6MDPigK9QTSBCam9ybiBIZWxnYWFzIDxoZWxnYWFzQGtlcm5lbC5vcmc+ IHdyb3RlOgo+ID4gPiA+IE9uIE1vbiwgRmViIDI0LCAyMDI1IGF0IDA1OjQ1OjM1UE0gKzA1MzAs IE5hdmVlbiBLdW1hciBQIHdyb3RlOgo+ID4gPiA+ID4gT24gV2VkLCBGZWIgMTksIDIwMjUgYXQg 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(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 39FF313B5B6; Tue, 25 Feb 2025 20:38:20 +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=1740515901; cv=none; b=ZZB7hSU6yfl29DQsAwC06IMJOrVkOo+yBPVUC5LIT7eZDhaXaYu1hbAReln0Zx3Nz1557z8FV72qiS1vR3Y9BsrAYexcpo0R3e0mMU7MwCUVOnJ5m/ySUBSEp40pB170VaK84epsfrvaDgnN4oTYb/6QfJpsPJH1BAbozoJ4Vz8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740515901; c=relaxed/simple; bh=J2rkB2PHUhOcdIxRiQMlCkNw1+TaIn4gTsxuIvAhsoo=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=MNF9zy/xMWOTDn+ivTdSw3hW4Bek0JvoZgu9TR6nFl8qI/npKLMT7VvwnD3jDZnb+eMHpCIXGFrw8JQqDAx3mnXUrz9ey3GIUvjJqpSRvMsacpvgTEJ7NSGh7jTKuWi7VHOa/tYC6Wr4beu7FLIbqIhtvY4HJ9qkroDgr/gsBQU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GGrtdVth; 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="GGrtdVth" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8051FC4CEDD; Tue, 25 Feb 2025 20:38:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740515900; bh=J2rkB2PHUhOcdIxRiQMlCkNw1+TaIn4gTsxuIvAhsoo=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=GGrtdVthoxLVMlEI/fF8VwHYL/Yw7TMYgSCbDxAM7dUxLvnktgJFAcBNpBxvOZZ/M bIN9kq4blyIwTx+m3XVuXnGOh3iMLQ5IkK+eRCNVL4J8OzpzHnDzywLlyWYKZAj+R8 zvcP75LCQUidbJaQ0wvtMu1m1KIMalzVJhmHhLP86DyoMpQBwlidgtTPjBbWXT0tFG ivY846gbSAMcjYa9OuBLh3DDZ0/yX/XM6Xx8s5IvVWidW1yL3t/7CSB1hhWPep73+x JO/N/J6XjENKEgwNDFm18UNX2mzY6Ylo2cPOcJAb3Luo+O/QIXqqki64UDBINWUGoN hU6tkRHgi5qMQ== Date: Tue, 25 Feb 2025 14:38:18 -0600 From: Bjorn Helgaas To: Naveen Kumar P Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, kernelnewbies , linux-acpi@vger.kernel.org Subject: Re: PCI: hotplug_event: PCIe PLDA Device BAR Reset Message-ID: <20250225203818.GA516645@bhelgaas> Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Tue, Feb 25, 2025 at 06:46:02PM +0530, Naveen Kumar P wrote: > On Tue, Feb 25, 2025 at 1:24 AM Bjorn Helgaas wrote: > > On Tue, Feb 25, 2025 at 12:29:00AM +0530, Naveen Kumar P wrote: > > > On Mon, Feb 24, 2025 at 11:03 PM Bjorn Helgaas wrote: > > > > On Mon, Feb 24, 2025 at 05:45:35PM +0530, Naveen Kumar P wrote: > > > > > On Wed, Feb 19, 2025 at 10:36 PM Bjorn Helgaas wrote: > > > > > > On Wed, Feb 19, 2025 at 05:52:47PM +0530, Naveen Kumar P wrote: > > > > > > > Hi all, > > > > > > > > > > > > > > I am writing to seek assistance with an issue we are experiencing with > > > > > > > a PCIe device (PLDA Device 5555) connected through PCI Express Root > > > > > > > Port 1 to the host bridge. > > > > > > > > > > > > > > We have observed that after booting the system, the Base Address > > > > > > > Register (BAR0) memory of this device gets reset to 0x0 after > > > > > > > approximately one hour or more (the timing is inconsistent). This was > > > > > > > verified using the lspci output and the setpci -s 01:00.0 > > > > > > > BASE_ADDRESS_0 command. > > > > > ... > > > I booted with the pcie_aspm=off kernel parameter, which means that > > > PCIe Active State Power Management (ASPM) is disabled. Given this > > > context, should I consider removing this setting to see if it affects > > > the occurrence of the Bus Check notifications and the BAR0 reset > > > issue? > > > > Doesn't seem likely to be related. Once configured, ASPM operates > > without any software intervention. But note that "pcie_aspm=off" > > means the kernel doesn't touch ASPM configuration at all, and any > > configuration done by firmware remains in effect. > > > > You can tell whether ASPM has been enabled by firmware with "sudo > > lspci -vv" before the problem occurs. > > > > > > > During the ACPI_NOTIFY_BUS_CHECK event, the lspci output initially > > > > > showed all FF's, and then the next run of the same command showed > > > > > BASE_ADDRESS_0 reset to zero: > > > > > $ sudo lspci -xxx -s 01:00.0 | grep "10:" > > > > > 10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > > > > > > > > Looks like the device isn't responding at all here. Could happen if > > > > the device is reset or powered down. > > > > > > From the kernel driver or user space tools, is it possible to > > > determine whether the device has been reset or powered down? Are > > > there any power management settings or configurations that could be > > > causing the device to reset or power down unexpectedly? > > > > Not really. By "powered down", I meant D3cold, where the main power > > is removed. Config space is readable in all other power states. > > > > > > What is this device? What driver is bound to it? I don't see > > > > anything in dmesg that identifies a driver. > > > > > > The PCIe device in question is a Xilinx FPGA endpoint, which is > > > flashed with RTL code to expose several host interfaces to the system > > > via the PCIe link. > > > > > > We have an out-of-tree driver for this device, but to eliminate the > > > driver's role in this issue, I renamed the driver to prevent it from > > > loading automatically after rebooting the machine. Despite not using > > > the driver, the issue still occurred. > > > > Oh, right, I forgot that you mentioned this before. > > > > > > You're seeing the problem on v5.4 (Nov 2019), which is much newer than > > > > v4.4 (Jan 2016). But v5.4 is still really too old to spend a lot of > > > > time on unless the problem still happens on a current kernel. > > > > This part is important. We don't want to spend a lot of time > > debugging an issue that may have already been fixed upstream. > > Sure, I started building the 6.13 kernel and will post more > information if I notice the issue on the 6.13 kernel. > > Regarding the CommClk- (Common Clock Configuration) bit, it indicates > whether the common clock configuration is enabled or disabled. When it > is set to CommClk-, it means that the common clock configuration is > disabled. > > LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk- > ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt- > > For my device, I noticed that the common clock configuration is > disabled. Could this be causing the BAR reset issue? Not to my knowledge. > How is the CommClk bit determined(to set or clear)? and is it okay to > enable this bit after booting the kernel? It is somewhere in drivers/pci/pcie/aspm.c, i.e., https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/pcie/aspm.c?id=v6.13#n383