On Tue, Sep 15, 2015 at 02:14:14PM -0500, Felipe Balbi wrote: > On Tue, Sep 15, 2015 at 03:04:58PM -0400, Alan Stern wrote: > > On Tue, 15 Sep 2015, Felipe Balbi wrote: > > > > > Instead of allowing a range of 2 to 4 requests, > > > let's allow the user choose up to 32 requests > > > as that will give us a better chance of keeping > > > controller busy. > > > > > > We still maintain default of 2 so users shouldn't > > > be affected. > > > > Was this change inspired by testing? What were the test results? > > yeah, this one yeah. With the changes to dwc3 above, I have a much > better chance of keeping the controller's queue busy with a deeper > usb_request queue length. That means that we will be avoid XferComplete > and a subsequent XferNotReady which translates directly to less NAK/NYET > handshakes in the bus. Also less POLLs. oh yeah, and this is probably more important for USB3 controllers which can add more transfers to the controller's queue while the controller is processing something currently. -- balbi
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