From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758066AbdEVNCu (ORCPT ); Mon, 22 May 2017 09:02:50 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:50708 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757311AbdEVNCq (ORCPT ); Mon, 22 May 2017 09:02:46 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 2267B6073B Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=sricharan@codeaurora.org Subject: Re: [PATCH V4 3/4] ACPI/IORT: Ignore all errors except EPROBE_DEFER To: Lorenzo Pieralisi Cc: robin.murphy@arm.com, will.deacon@arm.com, joro@8bytes.org, iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, m.szyprowski@samsung.com, bhelgaas@google.com, linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org, tn@semihalf.com, hanjun.guo@linaro.org, okaya@codeaurora.org, robh+dt@kernel.org, frowand.list@gmail.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, sudeep.holla@arm.com, rjw@rjwysocki.net, lenb@kernel.org, catalin.marinas@arm.com, arnd@arndb.de, linux-arch@vger.kernel.org, laurent.pinchart@ideasonboard.com, j.neuschaefer@gmx.net, geert@linux-m68k.org, magnus.damm@gmail.com References: <1495119257-26724-1-git-send-email-sricharan@codeaurora.org> <1495119257-26724-3-git-send-email-sricharan@codeaurora.org> <20170522103730.GB7553@red-moon> <20170522113116.GB10449@red-moon> From: Sricharan R Message-ID: <0c599944-5815-778b-57ae-5b3a6105c8d4@codeaurora.org> Date: Mon, 22 May 2017 18:32:29 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <20170522113116.GB10449@red-moon> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Lorenzo, On 5/22/2017 5:01 PM, Lorenzo Pieralisi wrote: > On Mon, May 22, 2017 at 04:35:43PM +0530, Sricharan R wrote: >> Hi Lorenzo, >> >> On 5/22/2017 4:07 PM, Lorenzo Pieralisi wrote: >>> Hi Sricharan, >>> >>> On Thu, May 18, 2017 at 08:24:16PM +0530, Sricharan R wrote: >>>> While deferring the probe of IOMMU masters, xlate and >>>> add_device callbacks called from iort_iommu_configure >>>> can pass back error values like -ENODEV, which means >>>> the IOMMU cannot be connected with that master for real >>>> reasons. Before the IOMMU probe deferral, all such errors >>>> were ignored. Now all those errors are propagated back, >>>> killing the master's probe for such errors. Instead ignore >>>> all the errors except EPROBE_DEFER, which is the only one >>>> of concern and let the master work without IOMMU, thus >>>> restoring the old behavior. >>>> >>>> Fixes: 5a1bb638d567 ("drivers: acpi: Handle IOMMU lookup failure with deferred probing or error") >>>> Signed-off-by: Sricharan R >>>> --- >>>> [V4] Added this patch newly. >>>> >>>> drivers/acpi/arm64/iort.c | 6 ++++++ >>>> 1 file changed, 6 insertions(+) >>>> >>>> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c >>>> index c5fecf9..16e101f 100644 >>>> --- a/drivers/acpi/arm64/iort.c >>>> +++ b/drivers/acpi/arm64/iort.c >>>> @@ -782,6 +782,12 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev) >>>> if (err) >>>> ops = ERR_PTR(err); >>>> >>>> + /* Ignore all other errors apart from EPROBE_DEFER */ >>>> + if (IS_ERR(ops) && (PTR_ERR(ops) != -EPROBE_DEFER)) { >>>> + dev_dbg(dev, "Adding to IOMMU failed: %ld\n", PTR_ERR(ops)); >>>> + ops = NULL; >>>> + } >>>> + >>>> return ops; >>>> } >>>> >>> >>> It is getting a bit convoluted. Is not it better to propagate the >>> error back and let acpi_dma_configure() make a decision accordingly ? >>> >> >> ok, I was trying to keep it in same way as DT, where of_dma_configure >> (here acpi_dma_configure) calls of_iommu_configure(here iort_iommu_configure) >> which ends up doing the check. So will have to be changed in both places >> for symmetry. >> >>> Something like: >>> >>> -- >8 -- >>> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c >>> index e39ec7b..3a10d757 100644 >>> --- a/drivers/acpi/scan.c >>> +++ b/drivers/acpi/scan.c >>> @@ -1371,8 +1371,8 @@ int acpi_dma_configure(struct device *dev, enum dev_dma_attr attr) >>> iort_set_dma_mask(dev); >>> >>> iommu = iort_iommu_configure(dev); >>> - if (IS_ERR(iommu)) >>> - return PTR_ERR(iommu); >>> + if (IS_ERR(iommu) && PTR_ERR(iommu) == -EPROBE_DEFER) >>> + return -EPROBE_DEFER; >> >> In case of other errors apart from EPROBE_DEFER, >> iommu = NULL should be set, before passing it on to >> arch_setup_dma_ops. > > Ah yes, sorry, that makes it uglier :( > > Point is, it does not make sense to me to have of/acpi_dma_configure() > check a return code with (IS_ERR()) whilst we know the only error > code you are allowed to handle is -EPROBE_DEFER, while at it it is > better to make the -EPROBE_DEFER check explicit (otherwise it may > seem that of/acpi_dma_configure() can handle an error code that > is different from -EPROBE_DEFER - but they don't), no big deal either > way though. > ok, in which case, the above check that you have shown to be added additionally to the original patch. Regards, Sricharan -- "QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation