Re: [PATCH V5 8/9] PCI: OF: Move of_pci_dma_configure() to pci_dma_configure()

From: Suravee Suthikulanit
Date: Wed Nov 18 2015 - 11:55:17 EST

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@xxxxxxx>
Acked-by: Rob Herring <robh+dt@xxxxxxxxxx>
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Reviewed-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
CC: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
+ * 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.


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)?


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