Deucher, Alexander wrote: >> Even the latest driver lacks the PCI IDs of many HDMI HDA devices >> (aa50/aa58/aa60/aa68/aa80/aa88/aa90/aa98: Cypress/Juniper/Redwood/Cedar/ >> Cayman+Antilles/Barts/Turks/Caicos). >> >> Alex, are these devices that require disabling snooping? > > Sorry what does snooping mean in this context? Coherent memory accesses, i.e., not setting bit 18 in the stream descriptor control register; the HDA spec says: | Traffic Priority (TP): If set to a 1, the stream will be treated as | preferred traffic if the underlying bus supports it. If set to a 0, | the traffic will be handled on a “best effort” basis. [...] | On PCI Express, for example, setting the TP bit to a 1 might cause | the controller to generate non-snooped isochronous traffic, while | a PCI implementation may ignore this bit. | It is permitted to implement this bit as RO if there is no | controllability available. So "require" might be wrong, this is just an optimization. Anyway, devices up to aa48 use snooping, while from aaa0 (Tahiti XT) forward, the driver sets TP (<http://git.kernel.org/linus/1815b34a6267>). The question is, what was the first device to support this? Regards, Clemens ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
