linux-kernel - Re: [PATCH V5 8/9] PCI: OF: Move of_pci_dma_configure() to pci_dma

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Message-ID: <564CAD63.3020306@amd.com>
Date:	Wed, 18 Nov 2015 10:54:59 -0600
From:	Suravee Suthikulanit <suravee.suthikulpanit@....com>
To:	Arnd Bergmann <arnd@...db.de>, Robin Murphy <robin.murphy@....com>
CC:	<bhelgaas@...gle.com>, <rjw@...ysocki.net>, <lenb@...nel.org>,
	<catalin.marinas@....com>, <will.deacon@....com>,
	<thomas.lendacky@....com>, <herbert@...dor.apana.org.au>,
	<linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-acpi@...r.kernel.org>, <hanjun.guo@...aro.org>,
	<davem@...emloft.net>, <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH V5 8/9] PCI: OF: Move of_pci_dma_configure() to
 pci_dma_configure()

Hi All,

On 11/18/2015 6:41 AM, Arnd Bergmann wrote:
> On Wednesday 18 November 2015 12:00:32 Robin Murphy wrote:
>> On 17/11/15 15:00, Robin Murphy wrote:
>>> On 28/10/15 22:50, Suravee Suthikulpanit wrote:
>>>> Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
>>>> Acked-by: Rob Herring <robh+dt@...nel.org>
>>>> Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
>>>> Reviewed-by: Hanjun Guo <hanjun.guo@...aro.org>
>>>> CC: Rafael J. Wysocki <rjw@...ysocki.net>
>> [...]
>>>> +/**
>>>> + * pci_dma_configure - Setup DMA configuration
>>>> + * @dev: ptr to pci_dev struct of the PCI device
>>>> + *
>>>> + * Function to update PCI devices's DMA configuration using the same
>>>> + * info from the OF node of host bridge's parent (if any).
>>>> + */
>>>> +static void pci_dma_configure(struct pci_dev *dev)
>>>> +{
>>>> +    struct device *bridge = pci_get_host_bridge_device(dev);
>>>> +
>>>> +    if (IS_ENABLED(CONFIG_OF) && dev->dev.of_node) {
>>>
>>> Previously I was seeing of_dma_configure, and thus of_iommu_configure,
>>> called for every PCI device on Juno. The check above now prevents this
>>> happening, since the PCI devices are probed directly from the bus and
>>> don't have OF nodes of their own. They now get left in some
>>> half-configured state where arch_setup_dma_ops isn't called either.
>>
>> Just to follow up on that, Arnd's patch to tidy up dma_get_ops (now
>> queued[1]) makes this even worse, since preventing arch_setup_dma_ops
>> being called means the PCI devices now get the dummy DMA ops which leave
>> the drivers failing to probe at all, IOMMU hacks or not
>
> Ok, glad we found that with my patch then. We really have to
> configure the DMA (offset/size/coherency/iommu) for all devices that might
> be masters, otherwise things can randomly go wrong.
>
> 	ARnd

Robin is correct. Thanks for catching the bug. Rafael, do you want me to 
submit just the fixed-up patch on top of what we had earlier. Or do you 
want a new revision (V6)?

Thanks,
Suravee

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