From: Michael K. <ka...@ph...> - 2006-10-16 18:02:25
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Hello, With a Thinkpad T20 after applying the fix I posted in https://bugs.freedesktop.org/show_bug.cgi?id=8662 I noticed following problems with vertex DMA enabled: Vertex DMA hangs (i.e. no triangle is painted at all, 3D engine hangs, tested using a simple handmade program that sends a draw-request for the front-buffer to the DRM) after the processor entering C3 state or after an suspend-to-ram/resume cycle (with vanilla 2.6.18 ACPI), independant of C3 usage. The settings used are "DmaType AGP", "BusType AGP", "AGPMode 2", "ShadowStatus Off". This looks like a bus mastering problem, especially the C3 state problem (vertex dma works like a charm with max_cstate=2), but lspci -H1 -vv still shows the master bit on the graphics card set. Any further ideas how to track this bug down? Furthermore, the problem disappears (incurring a performance drop from 380 fps (AGP/VDMA) to 300 fps for gears, standard window size, 16bpp) when using PCI DMA instead of AGP DMA. (The 300 fps for PCI are independent of vertex DMA enabled or disabled. AGP with vertex DMA disabled is also 300 fps), so it might be an agpgart problem (this computer uses the Intel 440BX chipset and thus the intel_agp driver) Michael Karcher |
From: Alex D. <ale...@gm...> - 2006-10-23 01:39:26
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On 10/16/06, Michael Karcher <ka...@ph...> wrote: > Hello, > > With a Thinkpad T20 after applying the fix I posted in > https://bugs.freedesktop.org/show_bug.cgi?id=8662 I noticed following > problems with vertex DMA enabled: Vertex DMA hangs (i.e. no triangle is > painted at all, 3D engine hangs, tested using a simple handmade program > that sends a draw-request for the front-buffer to the DRM) after the > processor entering C3 state or after an suspend-to-ram/resume cycle > (with vanilla 2.6.18 ACPI), independant of C3 usage. The settings used > are "DmaType AGP", "BusType AGP", "AGPMode 2", "ShadowStatus Off". > > This looks like a bus mastering problem, especially the C3 state problem > (vertex dma works like a charm with max_cstate=2), but lspci -H1 -vv > still shows the master bit on the graphics card set. Any further ideas > how to track this bug down? > > Furthermore, the problem disappears (incurring a performance drop from > 380 fps (AGP/VDMA) to 300 fps for gears, standard window size, 16bpp) > when using PCI DMA instead of AGP DMA. (The 300 fps for PCI are > independent of vertex DMA enabled or disabled. AGP with vertex DMA > disabled is also 300 fps), so it might be an agpgart problem (this > computer uses the Intel 440BX chipset and thus the intel_agp driver) This is a known problem. AGP is not properly re-initalized after resume. the work around at the moment is to use PCI DMA. There was some discussion about this a couple years ago on one of the DRI lists. Alex > > Michael Karcher > |