Subject: [PATCH 3/7] dmaengine: st_fdma: Add STMicroelectronics FDMA engine driver support

From: [email-masked] (Vinod Koul)
Date: Wed, 19 Aug 2015 21:10:07 +0530

On Wed, Jul 08, 2015 at 05:11:24PM +0100, Peter Griffin wrote:
> +static int
> +st_fdma_elf_sanity_check(struct st_fdma_dev *fdev, const struct firmware *fw)
> +{
> +	const char *fw_name = fdev->pdata->fw_name;
> +	struct elf32_hdr *ehdr;
> +	char class;
> +
> +	if (!fw) {
> +		dev_err(fdev->dev, "failed to load %s\n", fw_name);
> +		return -EINVAL;
> +	}
> +
> +	if (fw->size < sizeof(struct elf32_hdr)) {
sizeof(*ehdr) ?

> +		dev_err(fdev->dev, "Image is too small\n");
> +		return -EINVAL;
> +	}
> +
> +	ehdr = (struct elf32_hdr *)fw->data;
> +
> +	/* We only support ELF32 at this point */
> +	class = ehdr->e_ident[EI_CLASS];
> +	if (class != ELFCLASS32) {
> +		dev_err(fdev->dev, "Unsupported class: %d\n", class);
> +		return -EINVAL;
> +	}
> +
> +	if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB) {
> +		dev_err(fdev->dev, "Unsupported firmware endianness\n");
would be worth printing the value for debug

> +		return -EINVAL;
> +	}
> +
> +	if (fw->size < ehdr->e_shoff + sizeof(struct elf32_shdr)) {
> +		dev_err(fdev->dev, "Image is too small\n");
Again printing size helps when you get a log trace and have no idea why size
was small. Similar one other places

> +		dst = st_fdma_seg_to_mem(fdev, da, memsz);
> +		if (!dst) {
> +			dev_err(dev, "bad phdr da 0x%x mem 0x%x\n", da, memsz);
> +			break;
> +		}
> +
> +		if (phdr->p_filesz)
> +			memcpy(dst, elf_data + phdr->p_offset, filesz);
> +
> +		if (memsz > filesz)
> +			memset(dst + filesz, 0, memsz - filesz);
> +
> +		mem_loaded++;
> +	}
> +
> +	return (mem_loaded != fdev->drvdata->num_mem) ? -EINVAL : 0;
so you are not expecting any segment with PT_LOAD otherwise this check will
fail as num_mem is assigned from e_phnum.
Also perhaps EIO will be better return?

> +}
> +
> +static void st_fdma_enable(struct st_fdma_dev *fdev)
> +{
> +	unsigned long hw_id, hw_ver, fw_rev;
> +	u32 val;
> +
> +	/* disable CPU pipeline clock & reset cpu pipeline */
> +	val = FDMA_CLK_GATE_DIS | FDMA_CLK_GATE_RESET;
> +	fdma_write(fdev, val, CLK_GATE);

empty line here

> +	/* disable SLIM core STBus sync */
> +	fdma_write(fdev, FDMA_STBUS_SYNC_DIS, STBUS_SYNC);
> +	/* enable cpu pipeline clock */
> +	fdma_write(fdev, !FDMA_CLK_GATE_DIS, CLK_GATE);
> +
> +	/* clear int & cmd mailbox */
> +	fdma_write(fdev, ~0UL, INT_CLR);
> +	fdma_write(fdev, ~0UL, CMD_CLR);

here too

> +static int st_fdma_get_fw(struct st_fdma_dev *fdev)
> +{
> +	int ret;
> +
> +	init_completion(&fdev->fw_ack);
> +	atomic_set(&fdev->fw_loaded, 0);
> +
> +	ret = request_firmware_nowait(THIS_MODULE, FW_ACTION_HOTPLUG,
> +				      fdev->pdata->fw_name, fdev->dev,
> +				      GFP_KERNEL, fdev, st_fdma_fw_cb);

Isn't doing this in device probe too stringent and holding up load...

> +	fdesc = st_fdma_alloc_desc(fchan, sg_len);
> +	if (!fdesc) {
> +		dev_err(fchan->fdev->dev, "no memory for desc\n");
> +		return NULL;
> +	}
> +
> +	fdesc->iscyclic = false;
> +
> +	for_each_sg(sgl, sg, sg_len, i) {
> +		hw_node = fdesc->node[i].desc;
> +
> +		hw_node->next = fdesc->node[(i + 1) % sg_len].pdesc;
> +		hw_node->control = NODE_CTRL_REQ_MAP_DREQ(fchan->dreq_line);
> +
> +		if (direction == DMA_MEM_TO_DEV) {
> +			hw_node->control |= NODE_CTRL_SRC_INCR;
> +			hw_node->control |= NODE_CTRL_DST_STATIC;
> +			hw_node->saddr = sg_dma_address(sg);
> +			hw_node->daddr = fchan->cfg.dev_addr;
> +		} else {
> +			hw_node->control |= NODE_CTRL_SRC_STATIC;
> +			hw_node->control |= NODE_CTRL_DST_INCR;
> +			hw_node->saddr = fchan->cfg.dev_addr;
> +			hw_node->daddr = sg_dma_address(sg);
> +		}
> +
> +		hw_node->nbytes = sg_dma_len(sg);
> +		hw_node->generic.length = sg_dma_len(sg);
> +		hw_node->generic.sstride = 0;
> +		hw_node->generic.dstride = 0;

This looks quite similar to previous one, I think some bits can be reused

> +static int st_fdma_slave_config(struct dma_chan *chan,
> +				struct dma_slave_config *slave_cfg)
> +{
> +	u32 maxburst = 0, addr = 0;
> +	enum dma_slave_buswidth width;
> +	struct st_fdma_chan *fchan = to_st_fdma_chan(chan);
> +	int ch_id = fchan->vchan.chan.chan_id;
> +	struct st_fdma_dev *fdev = fchan->fdev;
> +
> +	if (slave_cfg->direction == DMA_DEV_TO_MEM) {

This is depreciated, you can't use direction here. Please save the fields and
then use them in prep_ call

Also this is quite big patch, consider splitting it up for faster review

-- 
~Vinod