From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sricharan R Subject: Re: [PATCH V4 3/4] ACPI/IORT: Ignore all errors except EPROBE_DEFER Date: Mon, 22 May 2017 18:32:29 +0530 Message-ID: <0c599944-5815-778b-57ae-5b3a6105c8d4@codeaurora.org> 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> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170522113116.GB10449@red-moon> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Lorenzo Pieralisi Cc: catalin.marinas-5wv7dgnIgG8@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, okaya-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org, frowand.list-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tn-nYOzD4b6Jr9Wk0Htik3J/w@public.gmane.org, magnus.damm-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-acpi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org, linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lenb-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, arnd-r2nGTMty4D4@public.gmane.org, linux-arm-msm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, j.neuschaefer-hi6Y0CQ0nG0@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, bhelgaas-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, rjw-LthD3rsA81gm4RdzfppkhA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, sudeep.holla-5wv7dgnIgG8@public.gmane.org List-Id: devicetree@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