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 753532253FF; Fri, 17 Oct 2025 13:45:56 +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=1760708756; cv=none; b=h0mbgcSgD0lYuwgzEZVhurnr9XLwBMkqLVK9EUlQ9lNzgRFyPs9yVsvlVvjgsLb1F0v7iOMZsXL4e0n2NZTrcfWoZcPktImUFOXMIFjcmaH7CmvF1wHJgVZUsXwF/MBxAtBi+2fXxjqShmZViIlf677w9fBErjQVOJDVZ5SOJiA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760708756; c=relaxed/simple; bh=tuwnSb9TH+cevkh2/f4qKgeRV6Xx5R3TxYUye1mrYXQ=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=garJXgz0veowjdvT0QYsWYEh6MZ7qXPb/4jUfW7aFQjf4xoi4svTGnScaj331iR1Q7/jk2MH+pR7gu2VrGvj1wKUsCBt10z1Fud72L4rEs5uQG9GXCSk03KEw4kXALTTiA7uJowb2dSkhsYsh2M4Y9Ql0UwLp+QTSJEXn2sQ92g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=srRHJW4n; 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="srRHJW4n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA58AC4CEE7; Fri, 17 Oct 2025 13:45:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760708756; bh=tuwnSb9TH+cevkh2/f4qKgeRV6Xx5R3TxYUye1mrYXQ=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=srRHJW4nQ1b0MVA9JNlW2F4ekn1+j9gKj63pFwk39saI8PUpq1ruf2WNlXSwTqumL 2Ex2TP2p1UFI0qI7Y3LwQ87X1aK/71pllKS3NaWNrGvd86HoT6LOCaeUkTBkHSdgYU 4+1bQGGUtWS2OHNWt4rw4VQDSHKfzM2AwTluewPyPZgmjoE7oqExowX+oK6V1+rPoN qauXtpkyTGw/DhLAtgINBExJmMY91MXlm4WofI2FeJBmOyQYJ7o+WZnlGCcoKCmsz2 D719sDFnCvDXzUFXZkQzp4VIGkoKN2Sy2wm73uZ92IUPsATzOl9Zd9lT/odA3JV1iG 9DIXzS1EXp56A== Date: Fri, 17 Oct 2025 08:45:54 -0500 From: Bjorn Helgaas To: Manivannan Sadhasivam Cc: Shawn Lin , Manivannan Sadhasivam , Niklas Cassel , Bjorn Helgaas , Lorenzo Pieralisi , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Rob Herring , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, "David E. Box" , Kai-Heng Feng , "Rafael J. Wysocki" , Heiner Kallweit , Chia-Lin Kao , Dragan Simic , linux-rockchip@lists.infradead.org, regressions@lists.linux.dev, FUKAUMI Naoki Subject: Re: [PATCH v2 1/2] PCI/ASPM: Override the ASPM and Clock PM states set by BIOS for devicetree platforms Message-ID: <20251017134554.GA1027663@bhelgaas> Precedence: bulk X-Mailing-List: linux-arm-msm@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: <4pm5tizc2c4c75h23izalhysuljnlfzpxuawhzezmnnqic2tdf@l2rcj24rmru3> On Fri, Oct 17, 2025 at 06:24:26PM +0530, Manivannan Sadhasivam wrote: > On Fri, Oct 17, 2025 at 08:19:11PM +0800, Shawn Lin wrote: > > 在 2025/10/17 星期五 18:04, Manivannan Sadhasivam 写道: > > > On Fri, Oct 17, 2025 at 05:47:44PM +0800, Shawn Lin wrote: > ... > > > > While we're on the topic of ASPM, may I ask a silly question? > > > > I saw the ASPM would only be configured once the function > > > > driver calling pci_enable_device. So if the modular driver > > > > hasn't been insmoded, the link will be in L0 even though there > > > > is no transcation on-going. What is the intention behind it? > > > > > > I don't see where ASPM is configured during pci_enable_device(). > > > It is currently configured for all devices during > > > pci_scan_slot(). > > > > This is the dump_stack() where I observed. If I compile NVMe > > driver as a module and never insmod it, the link is always in L0, > > namely ASPM Disabled. > > I guess this comment answers your question: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/pcie/aspm.c?h=v6.18-rc1#n1179 The comment is: * At this stage drivers haven't had an opportunity to change the * link policy setting. Enabling ASPM on broken hardware can cripple * it even before the driver has had a chance to disable ASPM, so * default to a safe level right now. If we're enabling ASPM beyond * the BIOS's expectation, we'll do so once pci_enable_device() is * called. I don't think relying on a driver to disable ASPM to avoid broken hardware is the right answer. If the driver is never loaded, we waste power. And if the user enables ASPM via sysfs, apparently the device may be crippled. I think it would be better to have an enumeration-time quirk to keep us from enabling ASPM. We might trip over some of this broken hardware, but I don't think there are very many drivers that fiddle with ASPM, so we should be able to be proactive about it. > But with the recent ASPM change, the ASPM settings for DT platforms > will be applied before pci_enable_device(). Also, the comment is > somewhat outdated as we generally do not want PCI client drivers to > enable/disable ASPM nowadays. They can however do it under specific > circumstances. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 83976CCD195 for ; Fri, 17 Oct 2025 13:46:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References: List-Owner; bh=eCMHFpOBnHk7i/M/Td5GSLA4CK5BJy8LfeJ4gWYKbZo=; b=lGmXFdCYmr585M 2f6Ve9UJGRVKogE4fF32UEbm3iifLOTHYKWlIgHKbI9utiWq6zrO2eCqa8/U6oe3KneYCGdkbR5vw p9bAmo85LNcLCgo3ajz6YzJmBShg4LUiTrB5UJoK5xy9jud+S/sGK2Ajekpnpvyx8OtVnSJhuGloH iHXsW62Lgr0uBr542yE+mOqIwzPKrjoFRfVNX4Hw+JliH675R4Zhw37NBj9V1TO8Xn2r+rdK/ZEfi sJn1c2Y+FYAFPwE288vqptwHS7GwHjWX9ZqloYrBQvEOlBxfA+dCTlk5BTVjujpIgT31QtjRE6Xll uhu82E/h/Z2OpN2UfUjg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v9kmM-00000007yCL-1F8F; Fri, 17 Oct 2025 13:45:58 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1v9kmK-00000007yBp-3WvH for linux-rockchip@lists.infradead.org; Fri, 17 Oct 2025 13:45:56 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 4A074602C0; Fri, 17 Oct 2025 13:45:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA58AC4CEE7; Fri, 17 Oct 2025 13:45:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760708756; bh=tuwnSb9TH+cevkh2/f4qKgeRV6Xx5R3TxYUye1mrYXQ=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=srRHJW4nQ1b0MVA9JNlW2F4ekn1+j9gKj63pFwk39saI8PUpq1ruf2WNlXSwTqumL 2Ex2TP2p1UFI0qI7Y3LwQ87X1aK/71pllKS3NaWNrGvd86HoT6LOCaeUkTBkHSdgYU 4+1bQGGUtWS2OHNWt4rw4VQDSHKfzM2AwTluewPyPZgmjoE7oqExowX+oK6V1+rPoN qauXtpkyTGw/DhLAtgINBExJmMY91MXlm4WofI2FeJBmOyQYJ7o+WZnlGCcoKCmsz2 D719sDFnCvDXzUFXZkQzp4VIGkoKN2Sy2wm73uZ92IUPsATzOl9Zd9lT/odA3JV1iG 9DIXzS1EXp56A== Date: Fri, 17 Oct 2025 08:45:54 -0500 From: Bjorn Helgaas To: Manivannan Sadhasivam Cc: Shawn Lin , Manivannan Sadhasivam , Niklas Cassel , Bjorn Helgaas , Lorenzo Pieralisi , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Rob Herring , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, "David E. Box" , Kai-Heng Feng , "Rafael J. Wysocki" , Heiner Kallweit , Chia-Lin Kao , Dragan Simic , linux-rockchip@lists.infradead.org, regressions@lists.linux.dev, FUKAUMI Naoki Subject: Re: [PATCH v2 1/2] PCI/ASPM: Override the ASPM and Clock PM states set by BIOS for devicetree platforms Message-ID: <20251017134554.GA1027663@bhelgaas> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <4pm5tizc2c4c75h23izalhysuljnlfzpxuawhzezmnnqic2tdf@l2rcj24rmru3> X-BeenThere: linux-rockchip@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Upstream kernel work for Rockchip platforms List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "Linux-rockchip" Errors-To: linux-rockchip-bounces+linux-rockchip=archiver.kernel.org@lists.infradead.org T24gRnJpLCBPY3QgMTcsIDIwMjUgYXQgMDY6MjQ6MjZQTSArMDUzMCwgTWFuaXZhbm5hbiBTYWRo YXNpdmFtIHdyb3RlOgo+IE9uIEZyaSwgT2N0IDE3LCAyMDI1IGF0IDA4OjE5OjExUE0gKzA4MDAs IFNoYXduIExpbiB3cm90ZToKPiA+IOWcqCAyMDI1LzEwLzE3IOaYn+acn+S6lCAxODowNCwgTWFu aXZhbm5hbiBTYWRoYXNpdmFtIOWGmemBkzoKPiA+ID4gT24gRnJpLCBPY3QgMTcsIDIwMjUgYXQg MDU6NDc6NDRQTSArMDgwMCwgU2hhd24gTGluIHdyb3RlOgo+IC4uLgoKPiA+ID4gPiBXaGlsZSB3 ZSdyZSBvbiB0aGUgdG9waWMgb2YgQVNQTSwgbWF5IEkgYXNrIGEgc2lsbHkgcXVlc3Rpb24/Cj4g PiA+ID4gSSBzYXcgdGhlIEFTUE0gd291bGQgb25seSBiZSBjb25maWd1cmVkIG9uY2UgdGhlIGZ1 bmN0aW9uCj4gPiA+ID4gZHJpdmVyIGNhbGxpbmcgcGNpX2VuYWJsZV9kZXZpY2UuIFNvIGlmIHRo ZSBtb2R1bGFyIGRyaXZlcgo+ID4gPiA+IGhhc24ndCBiZWVuIGluc21vZGVkLCB0aGUgbGluayB3 aWxsIGJlIGluIEwwIGV2ZW4gdGhvdWdoIHRoZXJlCj4gPiA+ID4gaXMgbm8gdHJhbnNjYXRpb24g b24tZ29pbmcuIFdoYXQgaXMgdGhlIGludGVudGlvbiBiZWhpbmQgaXQ/Cj4gPiA+IAo+ID4gPiBJ IGRvbid0IHNlZSB3aGVyZSBBU1BNIGlzIGNvbmZpZ3VyZWQgZHVyaW5nIHBjaV9lbmFibGVfZGV2 aWNlKCkuCj4gPiA+IEl0IGlzIGN1cnJlbnRseSBjb25maWd1cmVkIGZvciBhbGwgZGV2aWNlcyBk dXJpbmcKPiA+ID4gcGNpX3NjYW5fc2xvdCgpLgo+ID4gCj4gPiBUaGlzIGlzIHRoZSBkdW1wX3N0 YWNrKCkgd2hlcmUgSSBvYnNlcnZlZC4gSWYgSSBjb21waWxlIE5WTWUKPiA+IGRyaXZlciBhcyBh IG1vZHVsZSBhbmQgbmV2ZXIgaW5zbW9kIGl0LCB0aGUgbGluayBpcyBhbHdheXMgaW4gTDAsCj4g PiBuYW1lbHkgQVNQTSBEaXNhYmxlZC4KPiAKPiBJIGd1ZXNzIHRoaXMgY29tbWVudCBhbnN3ZXJz IHlvdXIgcXVlc3Rpb246Cj4gaHR0cHM6Ly9naXQua2VybmVsLm9yZy9wdWIvc2NtL2xpbnV4L2tl cm5lbC9naXQvdG9ydmFsZHMvbGludXguZ2l0L3RyZWUvZHJpdmVycy9wY2kvcGNpZS9hc3BtLmM/ aD12Ni4xOC1yYzEjbjExNzkKClRoZSBjb21tZW50IGlzOgoKICAgKiBBdCB0aGlzIHN0YWdlIGRy aXZlcnMgaGF2ZW4ndCBoYWQgYW4gb3Bwb3J0dW5pdHkgdG8gY2hhbmdlIHRoZQogICAqIGxpbmsg cG9saWN5IHNldHRpbmcuIEVuYWJsaW5nIEFTUE0gb24gYnJva2VuIGhhcmR3YXJlIGNhbiBjcmlw cGxlCiAgICogaXQgZXZlbiBiZWZvcmUgdGhlIGRyaXZlciBoYXMgaGFkIGEgY2hhbmNlIHRvIGRp c2FibGUgQVNQTSwgc28KICAgKiBkZWZhdWx0IHRvIGEgc2FmZSBsZXZlbCByaWdodCBub3cuIElm IHdlJ3JlIGVuYWJsaW5nIEFTUE0gYmV5b25kCiAgICogdGhlIEJJT1MncyBleHBlY3RhdGlvbiwg d2UnbGwgZG8gc28gb25jZSBwY2lfZW5hYmxlX2RldmljZSgpIGlzCiAgICogY2FsbGVkLgoKSSBk b24ndCB0aGluayByZWx5aW5nIG9uIGEgZHJpdmVyIHRvIGRpc2FibGUgQVNQTSB0byBhdm9pZCBi cm9rZW4KaGFyZHdhcmUgaXMgdGhlIHJpZ2h0IGFuc3dlci4gIElmIHRoZSBkcml2ZXIgaXMgbmV2 ZXIgbG9hZGVkLCB3ZSB3YXN0ZQpwb3dlci4gIEFuZCBpZiB0aGUgdXNlciBlbmFibGVzIEFTUE0g dmlhIHN5c2ZzLCBhcHBhcmVudGx5IHRoZSBkZXZpY2UKbWF5IGJlIGNyaXBwbGVkLgoKSSB0aGlu ayBpdCB3b3VsZCBiZSBiZXR0ZXIgdG8gaGF2ZSBhbiBlbnVtZXJhdGlvbi10aW1lIHF1aXJrIHRv IGtlZXAKdXMgZnJvbSBlbmFibGluZyBBU1BNLiAgV2UgbWlnaHQgdHJpcCBvdmVyIHNvbWUgb2Yg dGhpcyBicm9rZW4KaGFyZHdhcmUsIGJ1dCBJIGRvbid0IHRoaW5rIHRoZXJlIGFyZSB2ZXJ5IG1h bnkgZHJpdmVycyB0aGF0IGZpZGRsZQp3aXRoIEFTUE0sIHNvIHdlIHNob3VsZCBiZSBhYmxlIHRv IGJlIHByb2FjdGl2ZSBhYm91dCBpdC4KCj4gQnV0IHdpdGggdGhlIHJlY2VudCBBU1BNIGNoYW5n ZSwgdGhlIEFTUE0gc2V0dGluZ3MgZm9yIERUIHBsYXRmb3Jtcwo+IHdpbGwgYmUgYXBwbGllZCBi ZWZvcmUgcGNpX2VuYWJsZV9kZXZpY2UoKS4gQWxzbywgdGhlIGNvbW1lbnQgaXMKPiBzb21ld2hh dCBvdXRkYXRlZCBhcyB3ZSBnZW5lcmFsbHkgZG8gbm90IHdhbnQgUENJIGNsaWVudCBkcml2ZXJz IHRvCj4gZW5hYmxlL2Rpc2FibGUgQVNQTSBub3dhZGF5cy4gVGhleSBjYW4gaG93ZXZlciBkbyBp dCB1bmRlciBzcGVjaWZpYwo+IGNpcmN1bXN0YW5jZXMuCgpfX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fXwpMaW51eC1yb2NrY2hpcCBtYWlsaW5nIGxpc3QKTGlu dXgtcm9ja2NoaXBAbGlzdHMuaW5mcmFkZWFkLm9yZwpodHRwOi8vbGlzdHMuaW5mcmFkZWFkLm9y Zy9tYWlsbWFuL2xpc3RpbmZvL2xpbnV4LXJvY2tjaGlwCg==