When should we be targeting merge? At this point this is a substantial improvement over currently shipping kernels for our systems, and we don't really want to have to ship a patched / custom OS kernel if we can avoid it.
On 06/24/2018 08:09 PM, Russell Currey wrote: > On Sat, 2018-06-23 at 18:52 -0500, Timothy Pearson wrote: > > There's still more to do and this shouldn't be merged yet - would > encourage anyone with suitable hardware to test though. > >> POWER9 (PHB4) requires all peripherals using DMA to be either >> restricted >> to 32-bit windows or capable of accessing the entire 64 bits of >> memory >> space. Some devices, such as most GPUs, can only address up to a >> certain >> number of bits (approximately 40, in many cases), while at the same >> time >> it is highly desireable to use a larger DMA space than the fallback >> 32 bits. >> >> This series adds something called "cognitive DMA", which is a form of >> dynamic >> TCE allocation. This allows the peripheral to DMA to host addresses >> mapped in >> 1G (PHB4) or 256M (PHB3) chunks, and is transparent to the peripheral >> and its >> driver stack. >> >> This series has been tested on a Talos II server with a Radeon WX4100 >> and >> a wide range of OpenGL applications. While there is still work, >> notably >> involving what happens if a peripheral attempts to DMA close to a TCE >> window boundary, this series greatly improves functionality for AMD >> GPUs >> on POWER9 devices over the existing 32-bit DMA support. >> >> Russell Currey (4): >> powerpc/powernv/pci: Track largest available TCE order per PHB >> powerpc/powernv: DMA operations for discontiguous allocation >> powerpc/powernv/pci: Track DMA and TCE tables in debugfs >> powerpc/powernv/pci: Safety fixes for pseudobypass TCE allocation >> >> Timothy Pearson (3): >> powerpc/powernv/pci: Export pnv_pci_ioda2_tce_invalidate_pe >> powerpc/powernv/pci: Invalidate TCE cache after DMA map setup >> powerpc/powernv/pci: Don't use the lower 4G TCEs in pseudo-DMA mode >> >> arch/powerpc/include/asm/dma-mapping.h | 1 + >> arch/powerpc/platforms/powernv/Makefile | 2 +- >> arch/powerpc/platforms/powernv/pci-dma.c | 320 >> ++++++++++++++++++++++ >> arch/powerpc/platforms/powernv/pci-ioda.c | 169 ++++++++---- >> arch/powerpc/platforms/powernv/pci.h | 11 + >> 5 files changed, 452 insertions(+), 51 deletions(-) >> create mode 100644 arch/powerpc/platforms/powernv/pci-dma.c >> -- Timothy Pearson Raptor Engineering +1 (415) 727-8645 (direct line) +1 (512) 690-0200 (switchboard) https://www.raptorengineering.com
