On Friday 19 June 2009, Alan Stern wrote:
> On second thought, maybe it is better for sysfs to continue exporting
> the raw value in hex. The script can do all the necessary processing.
Hmm. What about the discrepancy that remains between bMaxPacketSize0 and
ep_*/wMaxPacketSize in that case?
> Here is how the value is encoded: Bits 0 - 10 contain the actual
> maxpacket size (this corresponds to a mask of 0x7ff). Bits 11 - 12
> contain a multiplicity value, to which you should add 1. (Bits 13 - 15
> are reserved for future use.)
This does the right thing then:
maxps_hex="0x`cat $eppath/wMaxPacketSize`"
# Extract MaxPS size (bits 0-10) and multiplicity values (bits 11-12)
maxps=`printf "%s*%s\n" $(($maxps_hex & 0x7ff)) \
$((1 + (($maxps_hex >> 11) & 0x3)))`
I'll send a new version of the script once we've sorted out remaining
issues.
Cheers,
FJP
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