On Mon, Apr 10, 2006 at 03:08:50PM -0600, Michael Downey wrote: > I am currently looking at using a MegTek USB insertion reader and I have > run into a problem with the current hiddev. The card reader returns a > 338 byte Input report on the interrupt in channel everytime a card is > inserted. The data contains basically all the information needed from > the card. The problem is that this one report is seen as 338 usage > references. So hiddev tries to build all the events for this report but > wraps it's buffer as it only allocates space for 64. I increased > HIDDEV_BUFFER_SIZE to 512 and everything worked correctly. > > My question is whether there would be any issue with increasing the > HIDDEV_BUFFER_SIZE to 512? I realize that this causes us to use 24 * > 512 bytes instead of 24 * 64 bytes. Is there any specific reason for > only allocating 64 or was it just a nice power of 2 number? The main > reason why we overflow this buffer is that we report a seperate event > for every report count on each usage. So in the case of this card > reader there are three usages with a report count of 110. So each of > these usages cause 110 seperate events to be generated. If we could > somehow pack all the similar data into a single buffer then this device > would only generate 11 events per insert instead of 338. This would > mean making changes to the file access structures which would likely > break things for other people. > > If no one has issues I will submit a patch to just up the > HIDDEV_BUFFER_SIZE to 512 from 64.
I don't see a problem with this, perhaps Vojtech remembers why the buffer size was set to 64. thanks, greg k-h ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
