Re: [PATCH 08/18] dma-mapping: add a new dma_alloc_noncoherent API

2020-09-25 Thread Christoph Hellwig
On Fri, Sep 25, 2020 at 12:15:37PM +0100, Robin Murphy wrote: > On 2020-09-15 16:51, Christoph Hellwig wrote: > [...] >> +These APIs allow to allocate pages in the kernel direct mapping that are >> +guaranteed to be DMA addressable. This means that unlike >> dma_alloc_coherent, >> +virt_to_page

Re: [PATCH 08/18] dma-mapping: add a new dma_alloc_noncoherent API

2020-09-25 Thread Robin Murphy
On 2020-09-15 16:51, Christoph Hellwig wrote: [...] +These APIs allow to allocate pages in the kernel direct mapping that are +guaranteed to be DMA addressable. This means that unlike dma_alloc_coherent, +virt_to_page can be called on the resulting address, and the resulting Nit: if we

[PATCH 08/18] dma-mapping: add a new dma_alloc_noncoherent API

2020-09-15 Thread Christoph Hellwig
Add a new API to allocate and free memory that is guaranteed to be addressable by a device, but which potentially is not cache coherent for DMA. To transfer ownership to and from the device, the existing streaming DMA API calls dma_sync_single_for_device and dma_sync_single_for_cpu must be used.