diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c index fc933a268986..7af886fc47af 100644 --- a/drivers/dma/dma-jz4780.c +++ b/drivers/dma/dma-jz4780.c @@ -214,11 +214,25 @@ static void jz4780_dma_desc_free(struct virt_dma_desc *vdesc) kfree(desc); } -static uint32_t jz4780_dma_transfer_size(unsigned long val, int *ord) +static uint32_t jz4780_dma_transfer_size(unsigned long val, uint32_t *shift) { - *ord = ffs(val) - 1; + int ord = ffs(val) - 1; - switch (*ord) { + /* + * 8 byte transfer sizes unsupported so fall back on 4. If it's larger + * than the maximum, just limit it. It is perfectly safe to fall back + * in this way since we won't exceed the maximum burst size supported + * by the device, the only effect is reduced efficiency. This is better + * than refusing to perform the request at all. + */ + if (ord == 3) + ord = 2; + else if (ord > 7) + ord = 7; + + *shift = ord; + + switch (ord) { case 0: return JZ_DMA_SIZE_1_BYTE; case 1: @@ -231,10 +245,8 @@ static uint32_t jz4780_dma_transfer_size(unsigned long val, int *ord) return JZ_DMA_SIZE_32_BYTE; case 6: return JZ_DMA_SIZE_64_BYTE; - case 7: - return JZ_DMA_SIZE_128_BYTE; default: - return -EINVAL; + return JZ_DMA_SIZE_128_BYTE; } } @@ -244,7 +256,6 @@ static uint32_t jz4780_dma_setup_hwdesc(struct jz4780_dma_chan *jzchan, { struct dma_slave_config *config = &jzchan->config; uint32_t width, maxburst, tsz; - int ord; if (direction == DMA_MEM_TO_DEV) { desc->dcm = JZ_DMA_DCM_SAI; @@ -271,8 +282,8 @@ static uint32_t jz4780_dma_setup_hwdesc(struct jz4780_dma_chan *jzchan, * divisible by the transfer size, and we must not use more than the * maximum burst specified by the user. */ - tsz = jz4780_dma_transfer_size(addr | len | (width * maxburst), &ord); - jzchan->transfer_shift = ord; + tsz = jz4780_dma_transfer_size(addr | len | (width * maxburst), + &jzchan->transfer_shift); switch (width) { case DMA_SLAVE_BUSWIDTH_1_BYTE: @@ -289,7 +300,7 @@ static uint32_t jz4780_dma_setup_hwdesc(struct jz4780_dma_chan *jzchan, desc->dcm |= width << JZ_DMA_DCM_SP_SHIFT; desc->dcm |= width << JZ_DMA_DCM_DP_SHIFT; - desc->dtc = len >> ord; + desc->dtc = len >> jzchan->transfer_shift; } static struct dma_async_tx_descriptor *jz4780_dma_prep_slave_sg( @@ -391,15 +402,13 @@ struct dma_async_tx_descriptor *jz4780_dma_prep_dma_memcpy( struct jz4780_dma_chan *jzchan = to_jz4780_dma_chan(chan); struct jz4780_dma_desc *desc; uint32_t tsz; - int ord; desc = jz4780_dma_desc_alloc(jzchan, 1, DMA_MEMCPY); if (!desc) return NULL; - tsz = jz4780_dma_transfer_size(dest | src | len, &ord); - if (tsz < 0) - return ERR_PTR(tsz); + tsz = jz4780_dma_transfer_size(dest | src | len, + &jzchan->transfer_shift); desc->desc[0].dsa = src; desc->desc[0].dta = dest;