On Thu, Jul 06, 2017 at 02:25:39PM +0200, Pierre-Yves MORDRET wrote:

+config STM32_MDMA
+	bool "STMicroelectronics STM32 master dma support"
+	depends on ARCH_STM32  || COMPILE_TEST

			    ^^^
why multiple spaces

+static enum dma_slave_buswidth stm32_mdma_get_max_width(u32 buf_len, u32 tlen)
+{
+	enum dma_slave_buswidth max_width = DMA_SLAVE_BUSWIDTH_8_BYTES;
+
+	while (((buf_len % max_width) || (tlen < max_width)) &&
+	       (max_width > DMA_SLAVE_BUSWIDTH_1_BYTE))
+		max_width = max_width >> 1;

ok, this is a bit hard to read...

+static int stm32_mdma_set_xfer_param(struct stm32_mdma_chan *chan,
+				     enum dma_transfer_direction direction,
+				     u32 *mdma_ccr, u32 *mdma_ctcr,
+				     u32 *mdma_ctbr, u32 buf_len)
+{
+	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
+	struct stm32_mdma_chan_config *chan_config = &chan->chan_config;
+	enum dma_slave_buswidth src_addr_width, dst_addr_width;
+	phys_addr_t src_addr, dst_addr;
+	int src_bus_width, dst_bus_width;
+	u32 src_maxburst, dst_maxburst, src_best_burst, dst_best_burst;
+	u32 ccr, ctcr, ctbr, tlen;
+
+	src_addr_width = chan->dma_config.src_addr_width;
+	dst_addr_width = chan->dma_config.dst_addr_width;
+	src_maxburst = chan->dma_config.src_maxburst;
+	dst_maxburst = chan->dma_config.dst_maxburst;
+	src_addr = chan->dma_config.src_addr;
+	dst_addr = chan->dma_config.dst_addr;

this doesn't seem right to me, only the periphral address would come from
slave_config, the memory address is passed as an arg to transfer..

...

+static int stm32_mdma_setup_xfer(struct stm32_mdma_chan *chan,
+				 struct stm32_mdma_desc *desc,
+				 struct scatterlist *sgl, u32 sg_len,
+				 enum dma_transfer_direction direction)
+{
+	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
+	struct dma_slave_config *dma_config = &chan->dma_config;
+	struct scatterlist *sg;
+	dma_addr_t src_addr, dst_addr;
+	u32 ccr, ctcr, ctbr;
+	int i, ret = 0;
+
+	for_each_sg(sgl, sg, sg_len, i) {
+		if (sg_dma_len(sg) > STM32_MDMA_MAX_BLOCK_LEN) {
+			dev_err(chan2dev(chan), "Invalid block len\n");
+			return -EINVAL;
+		}
+
+		ret = stm32_mdma_set_xfer_param(chan, direction, &ccr, &ctcr,
+						&ctbr, sg_dma_len(sg));
+		if (ret < 0)
+			return ret;
+
+		if (direction == DMA_MEM_TO_DEV) {
+			src_addr = sg_dma_address(sg);
+			dst_addr = dma_config->dst_addr;

and this seems correct, but then why are we doing it in
stm32_mdma_set_xfer_param()

+static struct dma_async_tx_descriptor *stm32_mdma_prep_slave_sg(
+	struct dma_chan *c, struct scatterlist *sgl,
+	u32 sg_len, enum dma_transfer_direction direction,
+	unsigned long flags, void *context)

right justfied these please, it makes a terrible read

+{
+	struct stm32_mdma_chan *chan = to_stm32_mdma_chan(c);
+	struct stm32_mdma_desc *desc;
+	int ret;
+
+	desc = stm32_mdma_alloc_desc(chan, sg_len);
+	if (!desc)
+		return NULL;
+
+	ret = stm32_mdma_setup_xfer(chan, desc, sgl, sg_len, direction);
+	if (ret < 0)
+		goto xfer_setup_err;
+
+	desc->cyclic = false;
+
+	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
+
+xfer_setup_err:
+	dma_pool_free(chan->desc_pool, &desc->hwdesc, desc->hwdesc_phys);
+	kfree(desc);
+	return NULL;
+}
+
+static struct dma_async_tx_descriptor *stm32_mdma_prep_dma_cyclic(
+	struct dma_chan *c, dma_addr_t buf_addr, size_t buf_len,
+	size_t period_len, enum dma_transfer_direction direction,
+	unsigned long flags)

here too and few other places

+static int stm32_mdma_probe(struct platform_device *pdev)
+{
+	struct stm32_mdma_chan *chan;
+	struct stm32_mdma_device *dmadev;
+	struct dma_device *dd;
+	struct device_node *of_node;
+	struct resource *res;
+	u32 nr_channels, nr_requests;
+	int i, count, ret;
+
+	of_node = pdev->dev.of_node;
+	if (!of_node)
+		return -ENODEV;
+
+	ret = of_property_read_u32(of_node, "dma-channels", &nr_channels);
+	if (ret)
+		nr_channels = STM32_MDMA_MAX_CHANNELS;
+
+	ret = of_property_read_u32(of_node, "dma-requests", &nr_requests);
+	if (ret)
+		nr_requests = STM32_MDMA_MAX_REQUESTS;

wouldn't it make sense to print error about these properties not being
present and continuing w/ defaults..?

and can we have device_property_xxx instead of of_ variants?

+static int __init stm32_mdma_init(void)
+{
+	return platform_driver_probe(&stm32_mdma_driver, stm32_mdma_probe);
+}
+
+subsys_initcall(stm32_mdma_init);

Where are the MODULE_xx tags, license is mandatory. You should add author
too.
 

-- 
~Vinod