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Subject[PATCH] firewire: Enable physical DMA above 4GB
Date
Quadlet reads to memory above 4GB is painfully slow when serviced
by the AR DMA context. In addition, the CPU(s) may be locked-up,
preventing any transfer at all.

Write the PhyUpperBound register with the end-of-memory value. If
end-of-memory is beyond the OHCI limit of 0x0000ffff00000000,
clamp to that value.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
drivers/firewire/ohci.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 044ace3..b4135a5 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -2249,6 +2249,7 @@ static int ohci_enable(struct fw_card *card,
struct pci_dev *dev = to_pci_dev(card->device);
u32 lps, version, irqs;
int i, ret;
+ u32 phys_upper;

if (software_reset(ohci)) {
dev_err(card->device, "failed to reset ohci card\n");
@@ -2323,7 +2324,10 @@ static int ohci_enable(struct fw_card *card,
reg_write(ohci, OHCI1394_FairnessControl, 0);
card->priority_budget_implemented = ohci->pri_req_max != 0;

- reg_write(ohci, OHCI1394_PhyUpperBound, 0x00010000);
+ phys_upper = min(0xffff0000ULL,
+ (dma_get_required_mask(card->device) >> 16) + 1);
+ reg_write(ohci, OHCI1394_PhyUpperBound, max(phys_upper, 0x00010000U));
+
reg_write(ohci, OHCI1394_IntEventClear, ~0);
reg_write(ohci, OHCI1394_IntMaskClear, ~0);

--
1.8.1.2


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