From mboxrd@z Thu Jan 1 00:00:00 1970 From: msalter@redhat.com (Mark Salter) Date: Fri, 19 Sep 2014 11:51:26 -0400 Subject: [PATCH] arm64/pci: fix dma coherency inheritance for PCI devices Message-ID: <1411141886-11310-1-git-send-email-msalter@redhat.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org The default dma_ops for devices on arm64 systems are noncoherent in nature and rely upon special operations and bounce buffers to perform a device DMA operation to/from memory. Some drivers rely upon coherent operations involving suitably capable hardware. In this case, a "dma-coherent" property will exist on the corresponding Device Tree node for the bridge device, or one of its ancestors. This patch adds support for applying a DMA coherent dma_ops for PCI devices in the case of such a property. Signed-off-by: Jon Masters [added search for device with of_node] Signed-off-by: Mark Salter --- arch/arm64/mm/dma-mapping.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index 4164c5a..0e26bd7 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -23,10 +23,12 @@ #include #include #include +#include #include #include #include #include +#include #include @@ -316,8 +318,18 @@ static int dma_bus_notifier(struct notifier_block *nb, if (event != BUS_NOTIFY_ADD_DEVICE) return NOTIFY_DONE; - if (of_property_read_bool(dev->of_node, "dma-coherent")) - set_dma_ops(dev, &coherent_swiotlb_dma_ops); + /* + * Some devices won't have an of_node but a bus controller/bridge will. + * Search up the device chain until we find an of_node to check. + */ + while (dev) { + if (dev->of_node) { + if (of_dma_is_coherent(dev->of_node)) + set_dma_ops(_dev, &coherent_swiotlb_dma_ops); + break; + } + dev = dev->parent; + } return NOTIFY_OK; } @@ -330,6 +342,10 @@ static struct notifier_block amba_bus_nb = { .notifier_call = dma_bus_notifier, }; +static struct notifier_block pci_bus_nb = { + .notifier_call = dma_bus_notifier, +}; + extern int swiotlb_late_init_with_default_size(size_t default_size); static int __init swiotlb_late_init(void) @@ -341,6 +357,7 @@ static int __init swiotlb_late_init(void) */ bus_register_notifier(&platform_bus_type, &platform_bus_nb); bus_register_notifier(&amba_bustype, &amba_bus_nb); + bus_register_notifier(&pci_bus_type, &pci_bus_nb); dma_ops = &noncoherent_swiotlb_dma_ops; -- 1.9.3