On Thu, Aug 31, 2017 at 06:58:17PM +0200, Alexander Steffen wrote: > The documentation says that DMA-safe memory is required for SPI transfers. > The I/O buffers passed in by the caller can be allocated anywhere, > including on the stack, which is not DMA-safe. So the data needs to be > copied to separate, DMA-safe buffers. > > We did not see any DMA-related issues on our test systems, even without > DMA-safe buffers. But this might simply be due to the fact that the SPI > transfer size is rather small, so our systems do not bother to set up DMA > transfers. Other systems might do so. > > v2: > - Updated commit message with more explanations. > > v3: > - Split into two patches, one for making the buffers DMA-safe and another > for using only a single buffer. > > Alexander Steffen (2): > tpm_tis_spi: Use DMA-safe memory for SPI transfers > tpm_tis_spi: Use a single buffer for SPI transfers > > drivers/char/tpm/tpm_tis_spi.c | 32 ++++++++++++++++++-------------- > 1 file changed, 18 insertions(+), 14 deletions(-) > > -- > 2.7.4 >
Great, I'll try to get means to test this! /Jarkko ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ tpmdd-devel mailing list tpmdd-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/tpmdd-devel
