Re: [PATCH v2 4/7] scatterlist: add sg_alloc_table_from_buf() helper
On Wed, Mar 30, 2016 at 05:39:51PM +0200, Boris Brezillon wrote: > sg_alloc_table_from_buf() provides an easy solution to create an sg_table > from a virtual address pointer. This function takes care of dealing with > vmallocated buffers, buffer alignment, or DMA engine limitations (maximum > DMA transfer size). This seems nice. Should we also have a further helper on top of this which will get constraints from a dmaengine, it seems like it'd be a common need? signature.asc Description: PGP signature
Re: [PATCH v2 4/7] scatterlist: add sg_alloc_table_from_buf() helper
On Wed, 30 Mar 2016 09:51:43 -0700 Mark Brown wrote: > On Wed, Mar 30, 2016 at 05:39:51PM +0200, Boris Brezillon wrote: > > sg_alloc_table_from_buf() provides an easy solution to create an sg_table > > from a virtual address pointer. This function takes care of dealing with > > vmallocated buffers, buffer alignment, or DMA engine limitations (maximum > > DMA transfer size). > > This seems nice. Should we also have a further helper on top of this > which will get constraints from a dmaengine, it seems like it'd be a > common need? Yep, we could create a wrapper extracting dma_slave caps info, converting it to sg_constraints and calling sg_alloc_table_from_buf(). But let's try to get this function accepted first, and I'll send another patch providing this wrapper. BTW, do you see other things that should be added in sg_constraints? -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v2 4/7] scatterlist: add sg_alloc_table_from_buf() helper
On Wed, Mar 30, 2016 at 08:18:31PM +0200, Boris Brezillon wrote: > BTW, do you see other things that should be added in sg_constraints? It looked to do everything SPI does which is everything I know about. signature.asc Description: PGP signature
Re: [PATCH v2 4/7] scatterlist: add sg_alloc_table_from_buf() helper
On 30/03/16 19:18, Boris Brezillon wrote: On Wed, 30 Mar 2016 09:51:43 -0700 Mark Brown wrote: On Wed, Mar 30, 2016 at 05:39:51PM +0200, Boris Brezillon wrote: sg_alloc_table_from_buf() provides an easy solution to create an sg_table from a virtual address pointer. This function takes care of dealing with vmallocated buffers, buffer alignment, or DMA engine limitations (maximum DMA transfer size). This seems nice. Should we also have a further helper on top of this which will get constraints from a dmaengine, it seems like it'd be a common need? Yep, we could create a wrapper extracting dma_slave caps info, converting it to sg_constraints and calling sg_alloc_table_from_buf(). But let's try to get this function accepted first, and I'll send another patch providing this wrapper. BTW, do you see other things that should be added in sg_constraints? You could compare with the things Solaris uses to describe the restrictions on a DMA binding ... http://docs.oracle.com/cd/E23824_01/html/821-1478/ddi-dma-attr-9s.html#REFMAN9Sddi-dma-attr-9s .Dave. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
