On 2012-04-13 16:39, Michael Grzeschik wrote: > Hi Arvid, > > On Fri, Apr 13, 2012 at 01:58:25PM +0000, Arvid Brodin wrote: >> On 2012-04-13 12:59, Michael Grzeschik wrote: >>> The errata2 workaround is described in the Datasheet as follows: >>> >>> An SOF INT can be used instead of an ATL INT with polling on Done >>> bits. A time-out can be implemented and if a certain Done bit is never >>> set, verification of the PTD completion can be done by reading PTD >>> contents (valid bit). This is a proven workaround implemented in >>> software. >>> >>> Therefore, we should do so, and ignore the check >>> for the ACTIVE_BIT in DW3. Because it is possible >>> that this bit is still set when the issue accures. >> >> I believe you trust the datasheet too much! :) I've tried this before (in fact, most of >> your code seems to be from an earlier patch of mine). It doesn't work, as explained in the >> comment to errata2_function() (and as tested with the usbtest/testusb suite). > > Yes, i know the older patches struggling with that issue. But in both > cases there were some details which does not fit to the exact errata2 > fix description. > > In the first patch (USB: isp1760: Implement solution for erratum 2) > the content checking (Valid Bit: 0) was totaly left out of sight. > > The second patch (usb/isp1760: Use polling instead of SOF interrupts to > fix Errata 2) was checking too much. As described above, the check for > the ACTIVE_BIT must not be done. > > In the current implementation we still run into hanging unhandled urbs > because they sometimes doesn't get both bits toggled. (V==0 && A==0) > > After solving this, it is easy to change the polling function back to > always enabled interrupts. In fact the enabling of SOF Interrupts > doesn't have anything else in mind than to guarantee that we never run > out of interrupts. That actually is nothing else then polling in > hardware. Instead of doing it with a timer function. Aha, I missed the removal of the ACTIVE_BIT==0 check in the patch. Nice find! So your patch is really doing two things: 1) Remove the ACTIVE_BIT==0 check - this fixes the bug you are hitting. Great! 2) Switch from software timer checking at ~5 Hz to SOF interrupt checking at, was it 1 kHz? Is this really neccessary/useful? -- Arvid Brodin Enea Services Stockholm AB - since February 16 a part of Xdin in the Alten Group. Soon we will be working under the common brand name Xdin. Read more at www.xdin.com.-- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
