Re: [PATCH v4 2/5] scsi: hisi_sas: Relocate some code to reduce complexity

[John Garry <john.garry@xxxxxxxxxx>]

On 06/12/2018 14:17, Johannes Thumshirn wrote:
> On 06/12/2018 14:34, John Garry wrote:
> [...]
> > +static void hisi_sas_dma_unmap(struct hisi_hba *hisi_hba,
> > +			       struct sas_task *task, int n_elem,
> > +			       int n_elem_req, int n_elem_resp)
> > +{
> > +	struct device *dev = hisi_hba->dev;
> > +
> > +	if (!sas_protocol_ata(task->task_proto)) {
> > +		if (task->num_scatter) {
> > +			if (n_elem)
> > +				dma_unmap_sg(dev, task->scatter,
> > +					     task->num_scatter,
> > +					     task->data_dir);
> > +		} else if (task->task_proto & SAS_PROTOCOL_SMP) {
> > +			if (n_elem_req)
> > +				dma_unmap_sg(dev, &task->smp_task.smp_req,
> > +					     1, DMA_TO_DEVICE);
> > +			if (n_elem_resp)
> > +				dma_unmap_sg(dev, &task->smp_task.smp_resp,
> > +					     1, DMA_FROM_DEVICE);
> > +		}
> > +	}
>
> 	if (sas_protocol_ata(task->task_proto))
> 		return;
>
> Would save you a level of indentation and make the above more readable.

Hi Johannes,

Whilst I agree with the idea, the current approach makes the function 
more symmetic with its mapping buddy, hisi_sas_dma_map():

static void hisi_sas_dma_unmap(struct hisi_hba *hisi_hba,
                   struct sas_task *task, int n_elem,
                   int n_elem_req, int n_elem_resp)
{
    struct device *dev = hisi_hba->dev;

    if (!sas_protocol_ata(task->task_proto)) {
        if (task->num_scatter) {
            if (n_elem)
                dma_unmap_sg(dev, task->scatter,

	...
}

static int hisi_sas_dma_map(struct hisi_hba *hisi_hba,
                struct sas_task *task, int *n_elem,
                int *n_elem_req, int *n_elem_resp)
{
    struct device *dev = hisi_hba->dev;
    int rc;

    if (sas_protocol_ata(task->task_proto)) {
        *n_elem = task->num_scatter;
    } else {
        unsigned int req_len, resp_len;

        if (task->num_scatter) {
            *n_elem = dma_map_sg(dev, task->scatter,
                         task->num_scatter, task->data_dir);
   		...

}

which is important. Let me know if you disagree and I can change it.

Thanks,
John