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SubjectRe: [PATCH v3] dmaengine: xgene-dma: Fix sparse wannings and coccinelle warnings
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On Friday 17 April 2015 14:41:02 Rameshwar Sahu wrote:
> >>
> >> -static void *xgene_dma_lookup_ext8(u64 *desc, int idx)
> >> +static __le64 *xgene_dma_lookup_ext8(struct xgene_dma_desc_hw *desc, int idx)
> >> {
> >> - return (idx % 2) ? (desc + idx - 1) : (desc + idx + 1);
> >> + switch (idx) {
> >> + case 0:
> >> + return &desc->m1;
> >> + case 1:
> >> + return &desc->m0;
> >> + case 2:
> >> + return &desc->m3;
> >> + case 3:
> >> + return &desc->m2;
> >> + default:
> >> + pr_err("Invalid dma descriptor index\n");
> >> + }
> >> +
> >> + return NULL;
> >> }
> >>
> > ...
> >
> >> /* Set 1st to 5th source addresses */
> >> for (i = 0; i < src_cnt; i++) {
> >> len = *nbytes;
> >> - xgene_dma_set_src_buffer((i == 0) ? (desc1 + 8) :
> >> + xgene_dma_set_src_buffer((i == 0) ? &desc1->m1 :
> >> xgene_dma_lookup_ext8(desc2, i - 1),
> >> &len, &src[i]);
> >> - XGENE_DMA_DESC_MULTI_SET(desc1, scf[i], i);
> >> + desc1->m2 |= cpu_to_le64((scf[i] << ((i + 1) * 8)));
> >> }
> >
> > If you just unroll this loop, you get code that is smaller and easier to
> > understand:
> >
> > /* Set 1st to 5th source addresses */
> > xgene_dma_set_src_buffer(&desc1->m1, &len, &src[0]);
> > xgene_dma_set_src_buffer(&desc2->m0, &len, &src[1]);
> > xgene_dma_set_src_buffer(&desc2->m3, &len, &src[2]);
> > xgene_dma_set_src_buffer(&desc2->m2, &len, &src[3]);
> > desc1->m2 |= cpu_to_le64(scf[0] | scf[1] << 8 | scf[2] << 16 | scf[3] << 24);
>
> Actually here, in run time src_cnt value can be 2 or 3 upto 5, so we
> can't unroll it.

I see, sorry for misreading the code. The patch is good then as it is.

Arnd


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