From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:50543 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752328AbcLETB2 (ORCPT ); Mon, 5 Dec 2016 14:01:28 -0500 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id uB5IwvGg090962 for ; Mon, 5 Dec 2016 14:01:28 -0500 Received: from e24smtp05.br.ibm.com (e24smtp05.br.ibm.com [32.104.18.26]) by mx0b-001b2d01.pphosted.com with ESMTP id 2756tebun8-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 05 Dec 2016 14:01:27 -0500 Received: from localhost by e24smtp05.br.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 5 Dec 2016 17:01:25 -0200 Subject: Re: [PATCH v2] of/irq: improve error report on irq discovery process failure To: Rob Herring References: <1480946356-16778-1-git-send-email-gpiccoli@linux.vnet.ibm.com> Cc: "linux-pci@vger.kernel.org" , "devicetree@vger.kernel.org" , linuxppc-dev , Mark Rutland , Benjamin Herrenschmidt , Frank Rowand , Marc Zyngier From: "Guilherme G. Piccoli" Date: Mon, 5 Dec 2016 17:01:20 -0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Message-Id: <5845B980.2030609@linux.vnet.ibm.com> Sender: linux-pci-owner@vger.kernel.org List-ID: On 12/05/2016 12:28 PM, Rob Herring wrote: > On Mon, Dec 5, 2016 at 7:59 AM, Guilherme G. Piccoli > wrote: >> On PowerPC machines some PCI slots might not have level triggered >> interrupts capability (also know as level signaled interrupts), >> leading of_irq_parse_pci() to complain by presenting error messages >> on the kernel log - in this case, the properties "interrupt-map" and >> "interrupt-map-mask" are not present on device's node in the device >> tree. >> >> This patch introduces a different message for this specific case, >> and also reduces its level from error to warning. Besides, we warn >> (once) that possibly some PCI slots on the system have no level >> triggered interrupts available. >> We changed some error return codes too on function of_irq_parse_raw() >> in order other failure's cases can be presented in a more precise way. >> >> Before this patch, when an adapter was plugged in a slot without level >> interrupts capabilitiy on PowerPC, we saw a generic error message >> like this: >> >> [54.239] pci 002d:70:00.0: of_irq_parse_pci() failed with rc=-22 >> >> Now, with this applied, we see the following specific message: >> >> [16.154] pci 0014:60:00.1: of_irq_parse_pci: no interrupt-map found, >> INTx interrupts not available >> >> Finally, we standardize the error path in of_irq_parse_raw() by always >> taking the fail path instead of returning directly from the loop. >> >> Signed-off-by: Guilherme G. Piccoli >> --- >> >> v2: >> * Changed function return code to always return negative values; > > Are you sure this is safe? This is tricky because of differing values > of NO_IRQ (0 or -1). Thanks Rob, but this is purely bad wording from myself. I'm sorry - I meant to say that I changed only my positive return code (that was suggested to be removed in the prior revision) to negative return code! So, I changed only code I added myself in v1 =) > >> * Improved/simplified warning outputs; >> * Changed some return codes and some error paths in of_irq_parse_raw() >> in order to be more precise/consistent; > > This too could have some side effects on callers. > > Not saying don't do these changes, just need some assurances this has > been considered. Thanks for your attention. I performed a quick investigation before changing this, all the places that use the return values are just getting "true/false" information from that, meaning they just are comparing to 0 basically. So change -EINVAL to -ENOENT wouldn't hurt any user of these return values, it'll only become more informative IMHO. Now, regarding the only error path that was changed: for some reason, this was the only place in which we didn't goto fail label in case of failure - it was added by a legacy commit from Ben, dated from 2006: 006b64de60 ("[POWERPC] Make OF irq map code detect more error cases"). Then it was carried by Grant Likely's commit 7dc2e1134a ("of/irq: merge irq mapping code"), 6-year old commit. I wasn't able to imagine a scenario in which changing this would break something; I believe the change improve consistency, but I'd remove it if you or somebody else thinks it worth be removed. Cheers, Guilherme > > Rob >