Hello.
Brian Rhodes wrote:
I just got my audio working this evening with a TLV320DAC32 DAC on a
near-copy of the DM6446 EVM board (we use the TLV320DAC32 instead of
the TLV320AIC33 and drop the I2C port expanders). I've had USB host
mode working for a while, but now when I try to use audio after
mounting a flash disk, or mount a flashdisk after using audio, I'm
getting various errors as shown below.
I thought I read a post here somewhere about a problem along these
lines, but I can't seem to find it in the archives. Is this anything
new? This is 2.6.31-rc7. CPPI DMA is enabled.
I constantly see alike messages when running USB test #12 (testusb.c
can be found at http://www.linux-usb.org/usbtest/).
We recently had this problem with one of our boards, but it appears to
have been completely a circuitry issue, though the driver may also
have a couple issues when there are some problems with the signals.
The board layout had some issues where the impedance was not being
maintained properly either because of distance between traces, or
switching layers on the board. I believe the major problem was a
couple of right angle turns in the traces which were causing signal
reflection. I have not heard that it was reproduced since our layout
issues were fixed.
I think the impedance between the differential pairs should be 90
ohms. We had one spot where that was not maintained to avoid a
through hole and a couple right angles in the traces close to the
connector.
That's interesting point...
The git kernel version which I was using was 2.6.30-rc7. I was
thinking perhaps musb_h_tx_flush_fifo should simply clear
MUSB_TXCSR_FLUSHFIFO from MUSB_TXCSR if it failed
This bit is self-clearing, and the register readback show it as
cleared, so there's no point.
so that at least USB could become usable again.
It is usable regardless.
Trying to recreate it just now is not proving easy. Even before it
was a fairly rare occurrence.
Try to use the aforementioned test suite...
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WBR, Sergei
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