Hello Alex Smith,
The patch d894fc6046fe: "dmaengine: jz4780: add driver for the
Ingenic JZ4780 DMA controller" from Mar 18, 2015, leads to the
following static checker warning:
drivers/dma/dma-jz4780.c:400 jz4780_dma_prep_dma_memcpy()
warn: unsigned 'tsz' is never less than zero.
drivers/dma/dma-jz4780.c
386 struct dma_async_tx_descriptor *jz4780_dma_prep_dma_memcpy(
387 struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
388 size_t len, unsigned long flags)
389 {
390 struct jz4780_dma_chan *jzchan = to_jz4780_dma_chan(chan);
391 struct jz4780_dma_desc *desc;
392 uint32_t tsz;
393 int ord;
394
395 desc = jz4780_dma_desc_alloc(jzchan, 1, DMA_MEMCPY);
396 if (!desc)
397 return NULL;
398
399 tsz = jz4780_dma_transfer_size(dest | src | len, &ord);
400 if (tsz < 0)
401 return ERR_PTR(tsz);
This code has unsigned leprosy. If you do a search for uint32_t you
will uncover several other mistakes. Also this function should be
returning NULL on error instead of "ERR_PTR(tsz)" or it leads to an
Oops.
402
403 desc->desc[0].dsa = src;
404 desc->desc[0].dta = dest;
405 desc->desc[0].drt = JZ_DMA_DRT_AUTO;
406 desc->desc[0].dcm = JZ_DMA_DCM_TIE | JZ_DMA_DCM_SAI | JZ_DMA_DCM_DAI |
407 tsz << JZ_DMA_DCM_TSZ_SHIFT |
408 JZ_DMA_WIDTH_32_BIT << JZ_DMA_DCM_SP_SHIFT |
409 JZ_DMA_WIDTH_32_BIT << JZ_DMA_DCM_DP_SHIFT;
410 desc->desc[0].dtc = len >> ord;
411
412 return vchan_tx_prep(&jzchan->vchan, &desc->vdesc, flags);
413 }
Other static checker warnings:
drivers/dma/dma-jz4780.c:747 jz4780_dma_probe() warn: unsigned 'jzdma->irq' is never less than zero.
drivers/dma/dma-jz4780.c:748 jz4780_dma_probe() warn: passing uninitialized 'ret'
regards,
dan carpenter
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