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

From: John Garry
Date: Tue Nov 03 2015 - 06:48:19 EST

On 02/11/2015 20:29, Arnd Bergmann wrote:
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.


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

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

Any reason this won't work?



There seems to be some misunderstanding. Are you suggesting I change sas_smp_task?
struct sas_smp_task {
struct scatterlist smp_req;
struct scatterlist smp_resp;


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