J.C. Wren 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.
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.
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 so that at least USB could become usable
again. Trying to recreate it just now is not proving easy. Even before
it was a fairly rare occurrence.
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