Re: [PATCH v10 1/3] dmaengine: 8250_mtk_dma: add MediaTek uart DMA support

On Mon, 2019-02-04 at 12:51 +0530, Vinod Koul wrote:

Hi Vinod sir,

On 18-01-19, 11:10, Long Cheng wrote:

quoted

+static enum dma_status mtk_uart_apdma_tx_status(struct dma_chan *chan,
+					 dma_cookie_t cookie,
+					 struct dma_tx_state *txstate)
+{
+	struct mtk_chan *c = to_mtk_uart_apdma_chan(chan);
+	enum dma_status ret;
+	unsigned long flags;
+
+	if (!txstate)
+		return DMA_ERROR;

Why, it is not a mandatory arg!

Next version, I will remove it.

quoted

+	ret = dma_cookie_status(chan, cookie, txstate);
+	spin_lock_irqsave(&c->vc.lock, flags);
+	if (ret == DMA_IN_PROGRESS) {
+		c->rx_status = mtk_uart_apdma_read(c, VFF_RPT) & VFF_RING_SIZE;
+		dma_set_residue(txstate, c->rx_status);
+	} else if (ret == DMA_COMPLETE && c->dir == DMA_DEV_TO_MEM) {
+		dma_set_residue(txstate, c->rx_status);

what is the point is setting residue to comleted txn, it is zero!

quoted

+	} else {
+		dma_set_residue(txstate, 0);

naah that doesnt sound correct!

Next version, I will modify the function.

quoted

+static void mtk_uart_apdma_config_write(struct dma_chan *chan,
+			       struct dma_slave_config *cfg,
+			       enum dma_transfer_direction dir)
+{
+	struct mtk_chan *c = to_mtk_uart_apdma_chan(chan);
+	struct mtk_uart_apdmadev *mtkd =
+				to_mtk_uart_apdma_dev(c->vc.chan.device);
+	unsigned int tmp;
+
+	if (mtk_uart_apdma_read(c, VFF_EN) == VFF_EN_B)
+		return;
+
+	c->dir = dir;
+
+	if (dir == DMA_DEV_TO_MEM) {
+		tmp = cfg->src_addr_width * 1024;

why multiply by 1024?

Next version, I will modify the this, with 'src_port_window_size' &&
'dst_port_window_size'.

quoted

+static int mtk_uart_apdma_device_pause(struct dma_chan *chan)
+{
+	/* just for check caps pass */
+	return 0;
+}

please remove, this is not a mandatory fn

Can't remove it. Before the mail, i had explained it. in 8250 uart
framework, will check the function..

thanks.