Ming Lei wrote: > > Suppose hcd->driver->dma_align_shift is zero and HC is byte aligned DMA > enabled, this means DMA is doable between byte aligned memory and HC, > but this does __not__ mean it is safe to do dma mapping or unmapping between > CPU and byte aligned memory, which may cause sync issues between memory > and CPU cache. kmalloc() already ensures that the memory it allocates is suitably aligned and sized to be safe for DMA. Therefore, any DMA transfers to/from a subsection of a kmalloc()'d buffer are also safe. David -- David Vrabel, Senior Software Engineer, Drivers CSR, Churchill House, Cambridge Business Park, Tel: +44 (0)1223 692562 Cowley Road, Cambridge, CB4 0WZ http://www.csr.com/ Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom -- 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
