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 X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 27693C433E0 for ; Thu, 28 May 2020 16:38:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9C142084C for ; Thu, 28 May 2020 16:38:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590683901; bh=rYOzZYw6qVcWw1+Bgcj/D7ePhlH1Yu7bCEXs98o9kyQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=ou0HTFZPHJBPhczldxGIwDKE08FiE06aaAu8FCL8qvInRCY0kVPe2Pt0LGLHxhXFx EsLLgaw0e18z1GjMonzgoFYILmpbiyH9+i3wKV6/saEBxmnvF3eUML785CrM+ba+NC BovUt7+3tFdVBnrgq1TdEf3ItNLA6VdfzEyC13L0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405141AbgE1QiS (ORCPT ); Thu, 28 May 2020 12:38:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:40366 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405066AbgE1QiM (ORCPT ); Thu, 28 May 2020 12:38:12 -0400 Received: from pali.im (pali.im [31.31.79.79]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C30A1207F5; Thu, 28 May 2020 16:38:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590683891; bh=rYOzZYw6qVcWw1+Bgcj/D7ePhlH1Yu7bCEXs98o9kyQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KM4GsGGiBme8F3C1xykXFeOmV5RsIvJclB1FhdnudGbtu6HE7QAttcQ9C9wzj09yO UquC0s0Yti69s9yLYQ7Ii2DKASs4aCyPR4iyHiiSBUCsc1wgoCd6WcXVh1xiKkEWe+ rHtIXrxYPUbQszvc85RV9TksBsRhjb9YRRZSzF/g= Received: by pali.im (Postfix) id 6CB79865; Thu, 28 May 2020 18:38:09 +0200 (CEST) Date: Thu, 28 May 2020 18:38:09 +0200 From: Pali =?utf-8?B?Um9ow6Fy?= To: Bjorn Helgaas Cc: Thomas Petazzoni , Lorenzo Pieralisi , Andrew Murray , Bjorn Helgaas , Marek =?utf-8?B?QmVow7pu?= , Remi Pommarel , Tomasz Maciej Nowak , Xogium , linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] PCI: aardvark: Don't touch PCIe registers if no card connected Message-ID: <20200528163809.54f5ldvphrjg3zg3@pali> References: <20200528143141.29956-1-pali@kernel.org> <20200528162604.GA323482@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200528162604.GA323482@bjorn-Precision-5520> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 28 May 2020 11:26:04 Bjorn Helgaas wrote: > On Thu, May 28, 2020 at 04:31:41PM +0200, Pali Rohár wrote: > > When there is no PCIe card connected and advk_pcie_rd_conf() or > > advk_pcie_wr_conf() is called for PCI bus which doesn't belong to emulated > > root bridge, the aardvark driver throws the following error message: > > > > advk-pcie d0070000.pcie: config read/write timed out > > > > Obviously accessing PCIe registers of disconnected card is not possible. > > > > Extend check in advk_pcie_valid_device() function for validating > > availability of PCIe bus. If PCIe link is down, then the device is marked > > as Not Found and the driver does not try to access these registers. > > > > Signed-off-by: Pali Rohár > > --- > > drivers/pci/controller/pci-aardvark.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c > > index 90ff291c24f0..53a4cfd7d377 100644 > > --- a/drivers/pci/controller/pci-aardvark.c > > +++ b/drivers/pci/controller/pci-aardvark.c > > @@ -644,6 +644,9 @@ static bool advk_pcie_valid_device(struct advk_pcie *pcie, struct pci_bus *bus, > > if ((bus->number == pcie->root_bus_nr) && PCI_SLOT(devfn) != 0) > > return false; > > > > + if (bus->number != pcie->root_bus_nr && !advk_pcie_link_up(pcie)) > > + return false; > > I don't think this is the right fix. This makes it racy because the > link may go down after we call advk_pcie_valid_device() but before we > perform the config read. Yes, it is racy, but I do not think it cause problems. Trying to read PCIe registers when device is not connected cause just those timeouts, printing error message and increased delay in advk_pcie_wait_pio() due to polling loop. This patch reduce unnecessary access to PCIe registers when advk_pcie_wait_pio() polling just fail. I think it is a good idea to not call blocking advk_pcie_wait_pio() when it is not needed. We could have faster enumeration of PCIe buses when card is not connected. > I have no objection to removing the "config read/write timed out" > message. The "return PCIBIOS_SET_FAILED" in the read case probably > should be augmented by setting "*val = 0xffffffff". > > > return true; > > } > > > > -- > > 2.20.1 > > 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 X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C15EC433DF for ; Thu, 28 May 2020 16:38:16 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id C27E72084C for ; Thu, 28 May 2020 16:38:15 +0000 (UTC) Authentication-Results: mail.kernel.org; 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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590683891; bh=rYOzZYw6qVcWw1+Bgcj/D7ePhlH1Yu7bCEXs98o9kyQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KM4GsGGiBme8F3C1xykXFeOmV5RsIvJclB1FhdnudGbtu6HE7QAttcQ9C9wzj09yO UquC0s0Yti69s9yLYQ7Ii2DKASs4aCyPR4iyHiiSBUCsc1wgoCd6WcXVh1xiKkEWe+ rHtIXrxYPUbQszvc85RV9TksBsRhjb9YRRZSzF/g= Received: by pali.im (Postfix) id 6CB79865; Thu, 28 May 2020 18:38:09 +0200 (CEST) Date: Thu, 28 May 2020 18:38:09 +0200 From: Pali =?utf-8?B?Um9ow6Fy?= To: Bjorn Helgaas Subject: Re: [PATCH] PCI: aardvark: Don't touch PCIe registers if no card connected Message-ID: <20200528163809.54f5ldvphrjg3zg3@pali> References: <20200528143141.29956-1-pali@kernel.org> <20200528162604.GA323482@bjorn-Precision-5520> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200528162604.GA323482@bjorn-Precision-5520> User-Agent: NeoMutt/20180716 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200528_093812_782744_C2165DCB X-CRM114-Status: GOOD ( 24.71 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Tomasz Maciej Nowak , Lorenzo Pieralisi , linux-pci@vger.kernel.org, Xogium , linux-kernel@vger.kernel.org, Marek =?utf-8?B?QmVow7pu?= , Remi Pommarel , Thomas Petazzoni , Bjorn Helgaas , linux-arm-kernel@lists.infradead.org, Andrew Murray Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gVGh1cnNkYXkgMjggTWF5IDIwMjAgMTE6MjY6MDQgQmpvcm4gSGVsZ2FhcyB3cm90ZToKPiBP biBUaHUsIE1heSAyOCwgMjAyMCBhdCAwNDozMTo0MVBNICswMjAwLCBQYWxpIFJvaMOhciB3cm90 ZToKPiA+IFdoZW4gdGhlcmUgaXMgbm8gUENJZSBjYXJkIGNvbm5lY3RlZCBhbmQgYWR2a19wY2ll X3JkX2NvbmYoKSBvcgo+ID4gYWR2a19wY2llX3dyX2NvbmYoKSBpcyBjYWxsZWQgZm9yIFBDSSBi dXMgd2hpY2ggZG9lc24ndCBiZWxvbmcgdG8gZW11bGF0ZWQKPiA+IHJvb3QgYnJpZGdlLCB0aGUg YWFyZHZhcmsgZHJpdmVyIHRocm93cyB0aGUgZm9sbG93aW5nIGVycm9yIG1lc3NhZ2U6Cj4gPiAK PiA+ICAgYWR2ay1wY2llIGQwMDcwMDAwLnBjaWU6IGNvbmZpZyByZWFkL3dyaXRlIHRpbWVkIG91 dAo+ID4gCj4gPiBPYnZpb3VzbHkgYWNjZXNzaW5nIFBDSWUgcmVnaXN0ZXJzIG9mIGRpc2Nvbm5l Y3RlZCBjYXJkIGlzIG5vdCBwb3NzaWJsZS4KPiA+IAo+ID4gRXh0ZW5kIGNoZWNrIGluIGFkdmtf cGNpZV92YWxpZF9kZXZpY2UoKSBmdW5jdGlvbiBmb3IgdmFsaWRhdGluZwo+ID4gYXZhaWxhYmls aXR5IG9mIFBDSWUgYnVzLiBJZiBQQ0llIGxpbmsgaXMgZG93biwgdGhlbiB0aGUgZGV2aWNlIGlz IG1hcmtlZAo+ID4gYXMgTm90IEZvdW5kIGFuZCB0aGUgZHJpdmVyIGRvZXMgbm90IHRyeSB0byBh Y2Nlc3MgdGhlc2UgcmVnaXN0ZXJzLgo+ID4gCj4gPiBTaWduZWQtb2ZmLWJ5OiBQYWxpIFJvaMOh ciA8cGFsaUBrZXJuZWwub3JnPgo+ID4gLS0tCj4gPiAgZHJpdmVycy9wY2kvY29udHJvbGxlci9w Y2ktYWFyZHZhcmsuYyB8IDMgKysrCj4gPiAgMSBmaWxlIGNoYW5nZWQsIDMgaW5zZXJ0aW9ucygr KQo+ID4gCj4gPiBkaWZmIC0tZ2l0IGEvZHJpdmVycy9wY2kvY29udHJvbGxlci9wY2ktYWFyZHZh cmsuYyBiL2RyaXZlcnMvcGNpL2NvbnRyb2xsZXIvcGNpLWFhcmR2YXJrLmMKPiA+IGluZGV4IDkw ZmYyOTFjMjRmMC4uNTNhNGNmZDdkMzc3IDEwMDY0NAo+ID4gLS0tIGEvZHJpdmVycy9wY2kvY29u dHJvbGxlci9wY2ktYWFyZHZhcmsuYwo+ID4gKysrIGIvZHJpdmVycy9wY2kvY29udHJvbGxlci9w Y2ktYWFyZHZhcmsuYwo+ID4gQEAgLTY0NCw2ICs2NDQsOSBAQCBzdGF0aWMgYm9vbCBhZHZrX3Bj aWVfdmFsaWRfZGV2aWNlKHN0cnVjdCBhZHZrX3BjaWUgKnBjaWUsIHN0cnVjdCBwY2lfYnVzICpi dXMsCj4gPiAgCWlmICgoYnVzLT5udW1iZXIgPT0gcGNpZS0+cm9vdF9idXNfbnIpICYmIFBDSV9T TE9UKGRldmZuKSAhPSAwKQo+ID4gIAkJcmV0dXJuIGZhbHNlOwo+ID4gIAo+ID4gKwlpZiAoYnVz LT5udW1iZXIgIT0gcGNpZS0+cm9vdF9idXNfbnIgJiYgIWFkdmtfcGNpZV9saW5rX3VwKHBjaWUp KQo+ID4gKwkJcmV0dXJuIGZhbHNlOwo+IAo+IEkgZG9uJ3QgdGhpbmsgdGhpcyBpcyB0aGUgcmln aHQgZml4LiAgVGhpcyBtYWtlcyBpdCByYWN5IGJlY2F1c2UgdGhlCj4gbGluayBtYXkgZ28gZG93 biBhZnRlciB3ZSBjYWxsIGFkdmtfcGNpZV92YWxpZF9kZXZpY2UoKSBidXQgYmVmb3JlIHdlCj4g cGVyZm9ybSB0aGUgY29uZmlnIHJlYWQuCgpZZXMsIGl0IGlzIHJhY3ksIGJ1dCBJIGRvIG5vdCB0 aGluayBpdCBjYXVzZSBwcm9ibGVtcy4gVHJ5aW5nIHRvIHJlYWQKUENJZSByZWdpc3RlcnMgd2hl biBkZXZpY2UgaXMgbm90IGNvbm5lY3RlZCBjYXVzZSBqdXN0IHRob3NlIHRpbWVvdXRzLApwcmlu dGluZyBlcnJvciBtZXNzYWdlIGFuZCBpbmNyZWFzZWQgZGVsYXkgaW4gYWR2a19wY2llX3dhaXRf cGlvKCkgZHVlCnRvIHBvbGxpbmcgbG9vcC4gVGhpcyBwYXRjaCByZWR1Y2UgdW5uZWNlc3Nhcnkg YWNjZXNzIHRvIFBDSWUgcmVnaXN0ZXJzCndoZW4gYWR2a19wY2llX3dhaXRfcGlvKCkgcG9sbGlu ZyBqdXN0IGZhaWwuCgpJIHRoaW5rIGl0IGlzIGEgZ29vZCBpZGVhIHRvIG5vdCBjYWxsIGJsb2Nr aW5nIGFkdmtfcGNpZV93YWl0X3BpbygpIHdoZW4KaXQgaXMgbm90IG5lZWRlZC4gV2UgY291bGQg aGF2ZSBmYXN0ZXIgZW51bWVyYXRpb24gb2YgUENJZSBidXNlcyB3aGVuCmNhcmQgaXMgbm90IGNv bm5lY3RlZC4KCj4gSSBoYXZlIG5vIG9iamVjdGlvbiB0byByZW1vdmluZyB0aGUgImNvbmZpZyBy ZWFkL3dyaXRlIHRpbWVkIG91dCIKPiBtZXNzYWdlLiAgVGhlICJyZXR1cm4gUENJQklPU19TRVRf RkFJTEVEIiBpbiB0aGUgcmVhZCBjYXNlIHByb2JhYmx5Cj4gc2hvdWxkIGJlIGF1Z21lbnRlZCBi eSBzZXR0aW5nICIqdmFsID0gMHhmZmZmZmZmZiIuCj4gCj4gPiAgCXJldHVybiB0cnVlOwo+ID4g IH0KPiA+ICAKPiA+IC0tIAo+ID4gMi4yMC4xCj4gPiAKCl9fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fCmxpbnV4LWFybS1rZXJuZWwgbWFpbGluZyBsaXN0Cmxp bnV4LWFybS1rZXJuZWxAbGlzdHMuaW5mcmFkZWFkLm9yZwpodHRwOi8vbGlzdHMuaW5mcmFkZWFk Lm9yZy9tYWlsbWFuL2xpc3RpbmZvL2xpbnV4LWFybS1rZXJuZWwK