From a7ba70f1787f977f970cd116076c6fce4b9e01cc Mon Sep 17 00:00:00 2001 From: Nicolas Saenz Julienne Date: Thu, 21 Nov 2019 10:26:44 +0100 Subject: dma-mapping: treat dev->bus_dma_mask as a DMA limit Using a mask to represent bus DMA constraints has a set of limitations. The biggest one being it can only hold a power of two (minus one). The DMA mapping code is already aware of this and treats dev->bus_dma_mask as a limit. This quirk is already used by some architectures although still rare. With the introduction of the Raspberry Pi 4 we've found a new contender for the use of bus DMA limits, as its PCIe bus can only address the lower 3GB of memory (of a total of 4GB). This is impossible to represent with a mask. To make things worse the device-tree code rounds non power of two bus DMA limits to the next power of two, which is unacceptable in this case. In the light of this, rename dev->bus_dma_mask to dev->bus_dma_limit all over the tree and treat it as such. Note that dev->bus_dma_limit should contain the higher accessible DMA address. Signed-off-by: Nicolas Saenz Julienne Reviewed-by: Robin Murphy Signed-off-by: Christoph Hellwig --- arch/mips/pci/fixup-sb1250.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) (limited to 'arch/mips') diff --git a/arch/mips/pci/fixup-sb1250.c b/arch/mips/pci/fixup-sb1250.c index 8a41b359cf90..40efc990cdce 100644 --- a/arch/mips/pci/fixup-sb1250.c +++ b/arch/mips/pci/fixup-sb1250.c @@ -21,22 +21,22 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIBYTE, PCI_DEVICE_ID_BCM1250_PCI, /* * The BCM1250, etc. PCI host bridge does not support DAC on its 32-bit - * bus, so we set the bus's DMA mask accordingly. However the HT link + * bus, so we set the bus's DMA limit accordingly. However the HT link * down the artificial PCI-HT bridge supports 40-bit addressing and the * SP1011 HT-PCI bridge downstream supports both DAC and a 64-bit bus * width, so we record the PCI-HT bridge's secondary and subordinate bus - * numbers and do not set the mask for devices present in the inclusive + * numbers and do not set the limit for devices present in the inclusive * range of those. */ -struct sb1250_bus_dma_mask_exclude { +struct sb1250_bus_dma_limit_exclude { bool set; unsigned char start; unsigned char end; }; -static int sb1250_bus_dma_mask(struct pci_dev *dev, void *data) +static int sb1250_bus_dma_limit(struct pci_dev *dev, void *data) { - struct sb1250_bus_dma_mask_exclude *exclude = data; + struct sb1250_bus_dma_limit_exclude *exclude = data; bool exclude_this; bool ht_bridge; @@ -55,7 +55,7 @@ static int sb1250_bus_dma_mask(struct pci_dev *dev, void *data) exclude->start, exclude->end); } else { dev_dbg(&dev->dev, "disabling DAC for device"); - dev->dev.bus_dma_mask = DMA_BIT_MASK(32); + dev->dev.bus_dma_limit = DMA_BIT_MASK(32); } return 0; @@ -63,9 +63,9 @@ static int sb1250_bus_dma_mask(struct pci_dev *dev, void *data) static void quirk_sb1250_pci_dac(struct pci_dev *dev) { - struct sb1250_bus_dma_mask_exclude exclude = { .set = false }; + struct sb1250_bus_dma_limit_exclude exclude = { .set = false }; - pci_walk_bus(dev->bus, sb1250_bus_dma_mask, &exclude); + pci_walk_bus(dev->bus, sb1250_bus_dma_limit, &exclude); } DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_SIBYTE, PCI_DEVICE_ID_BCM1250_PCI, quirk_sb1250_pci_dac); -- cgit v1.2.3