Re: [PATCH v2 27/32] scsi: hisi_sas: add smp protocol support

[Arnd Bergmann]

On Monday 02 November 2015 17:03:58 John Garry wrote:
> >
> > Can do. Actually sg_req seems only ever has one element:
> > expander.c, smp_execute_task()
> > sg_init_one(&task->smp_task.smp_req, req, req_size);
> >
> >
> I tried replacing with dma_map_single, but I feel the code is not as 
> clean as I need to manually set sg_dma_len() and sg_dma_address():
>      req_len = sg_dma_len(sg_req) = sg_req->length;
>      sg_dma_address(sg_req) = dma_map_single(dev, sg_virt(sg_req),
>                                          req_len, DMA_TO_DEVICE);
>      if (dma_mapping_error(dev, sg_dma_address(sg_req)))
>           return -ENOMEM;
> sg_dma_address(sg_req) is used in another function for unmap.
> 
> opinion?
> 

What I meant was not using a struct scatterlist at all:
replace the 'sg_req' variable with a normal pointer, and then
do

	hdr->cmd_table_addr = cpu_to_le64(dma_map_single(dev, req, len, DMA_TO_DEVICE));

Any reason this won't work?

	Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/