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| author | Eli Billauer <eli.billauer@gmail.com> | 2015-08-05 12:03:26 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-08-05 21:27:09 +0200 |
| commit | 6497a8757361a88b73fc3814d2ee9b9fc105fa42 (patch) | |
| tree | e29d833675458e61aecda860d94c753137351de4 /drivers/char/xillybus | |
| parent | Drivers: hv: vmbus: use cpu_hotplug_enable/disable (diff) | |
| download | linux-6497a8757361a88b73fc3814d2ee9b9fc105fa42.tar.xz linux-6497a8757361a88b73fc3814d2ee9b9fc105fa42.zip | |
char: xillybus: Allow 64-bit DMA on PCIe interface
Until now, only 32-bit DMA addressing was allowed, following a report on
some old Intel machine that dropped 64-bit PCIe packets, even though
pci_set_dma_mask() was successful with DMA_BIT_MASK(64).
But then came TI's Keystone II chip (ARM Cortex A15 + DSPs), which refuses
32-bit DMA addressing (for good reasons). So 64-bit DMA is allowed as a
fallback option.
Signed-off-by: Eli Billauer <eli.billauer@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/char/xillybus')
| -rw-r--r-- | drivers/char/xillybus/xillybus_pcie.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/drivers/char/xillybus/xillybus_pcie.c b/drivers/char/xillybus/xillybus_pcie.c index d8266bc2ae35..9418300214e9 100644 --- a/drivers/char/xillybus/xillybus_pcie.c +++ b/drivers/char/xillybus/xillybus_pcie.c @@ -193,14 +193,16 @@ static int xilly_probe(struct pci_dev *pdev, } /* - * In theory, an attempt to set the DMA mask to 64 and dma_using_dac=1 - * is the right thing. But some unclever PCIe drivers report it's OK - * when the hardware drops those 64-bit PCIe packets. So trust - * nobody and use 32 bits DMA addressing in any case. + * Some (old and buggy?) hardware drops 64-bit addressed PCIe packets, + * even when the PCIe driver claims that a 64-bit mask is OK. On the + * other hand, on some architectures, 64-bit addressing is mandatory. + * So go for the 64-bit mask only when failing is the other option. */ if (!pci_set_dma_mask(pdev, DMA_BIT_MASK(32))) { endpoint->dma_using_dac = 0; + } else if (!pci_set_dma_mask(pdev, DMA_BIT_MASK(64))) { + endpoint->dma_using_dac = 1; } else { dev_err(endpoint->dev, "Failed to set DMA mask. Aborting.\n"); return -ENODEV; |