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

Long Cheng
2019-02-14T02:44:56Z

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

Hi Vinod sir,

> On 18-01-19, 11:10, Long Cheng wrote:
> > +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.
>
> > + 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!
>
> > + } else {
> > + dma_set_residue(txstate, 0);
>
> naah that doesnt sound correct!
>
Next version, I will modify the function.

> > +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'.

> > +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.