On 30/01/2014 12:00 πμ, Sarah Sharp wrote:
On Wed, Jan 29, 2014 at 12:50:04PM +0200, Xenia Ragiadakou wrote:
On 29/01/2014 12:08 μμ, Rafał Miłecki wrote:
I've enabled some debugging in xhci-dbg.c, does it help?
xhci_hcd 0000:04:00.0: xHCI capability registers at ffffc90004e60000:
xhci_hcd 0000:04:00.0: CAPLENGTH AND HCIVERSION 0x960020:
xhci_hcd 0000:04:00.0: CAPLENGTH: 0x20
xhci_hcd 0000:04:00.0: HCIVERSION: 0x96
xhci_hcd 0000:04:00.0: HCSPARAMS 1: 0x4000820
xhci_hcd 0000:04:00.0: Max device slots: 32
xhci_hcd 0000:04:00.0: Max interrupters: 8
xhci_hcd 0000:04:00.0: Max ports: 4
xhci_hcd 0000:04:00.0: HCSPARAMS 2: 0x17f1
xhci_hcd 0000:04:00.0: Isoc scheduling threshold: 1
xhci_hcd 0000:04:00.0: Maximum allowed segments in event ring: 15
xhci_hcd 0000:04:00.0: HCSPARAMS 3 0x0:
xhci_hcd 0000:04:00.0: Worst case U1 device exit latency: 0
xhci_hcd 0000:04:00.0: Worst case U2 device exit latency: 0
xhci_hcd 0000:04:00.0: HCC PARAMS 0x200f180:
xhci_hcd 0000:04:00.0: HC generates 32 bit addresses
xhci_hcd 0000:04:00.0: FIXME: more HCCPARAMS debugging
xhci_hcd 0000:04:00.0: RTSOFF 0x1000:
Hi Rafał,
Like Bjørn already pointed out, I think too the problem is that the
USB3.0 host controller does not support 64 bit addressing (this can
be seen from the first bit of HCC PARAMS that is 0) but the patch
does not take it into account and blindly tries to perform 64bit
write accesses just because your system is 64bit. My mistake. I will
try to find a solution for that and send a patch when I ll return
home.
I think the solution should be to just revert the writeq patch, and
leave the xhci_write64 in place. We can always optimize that function
later to do a writeq if the host supports 64-bit writes, but we'll have
to analyze whether the performance impact of doing so makes sense.
Sarah Sharp
I think another solution could be to undefine writeq just before
including <asm-generic/io-64-nonatomic-lo-hi.h> header file, so that the
readq gets defined as two 32bit writes in low-high order.
If you think that that could be a solution, tell me and I can send a
patch to Rafał to test it when he has time.
regards,
ksenia
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