linux-kernel - Re: [PATCH 4/4] serial: 8250-mtk: modify uart DMA rx

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Date:   Tue, 21 May 2019 19:27:25 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Long Cheng <long.cheng@...iatek.com>
Cc:     Randy Dunlap <rdunlap@...radead.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Ryder Lee <ryder.lee@...iatek.com>,
        Sean Wang <sean.wang@...nel.org>,
        Nicolas Boichat <drinkcat@...omium.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        Sean Wang <sean.wang@...iatek.com>, dmaengine@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-serial@...r.kernel.org, srv_heupstream@...iatek.com,
        Yingjoe Chen <yingjoe.chen@...iatek.com>,
        YT Shen <yt.shen@...iatek.com>,
        Zhenbao Liu <zhenbao.liu@...iatek.com>
Subject: Re: [PATCH 4/4] serial: 8250-mtk: modify uart DMA rx

On 27-04-19, 11:36, Long Cheng wrote:
> Modify uart rx and complete for DMA.
> 
> Signed-off-by: Long Cheng <long.cheng@...iatek.com>
> ---
>  drivers/tty/serial/8250/8250_mtk.c |   53 ++++++++++++++++--------------------
>  1 file changed, 23 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
> index c1fdbc0..04081a6 100644
> --- a/drivers/tty/serial/8250/8250_mtk.c
> +++ b/drivers/tty/serial/8250/8250_mtk.c
> @@ -30,7 +30,6 @@
>  #define MTK_UART_DMA_EN_TX	0x2
>  #define MTK_UART_DMA_EN_RX	0x5
>  
> -#define MTK_UART_TX_SIZE	UART_XMIT_SIZE
>  #define MTK_UART_RX_SIZE	0x8000
>  #define MTK_UART_TX_TRIGGER	1
>  #define MTK_UART_RX_TRIGGER	MTK_UART_RX_SIZE
> @@ -64,28 +63,30 @@ static void mtk8250_dma_rx_complete(void *param)
>  	struct mtk8250_data *data = up->port.private_data;
>  	struct tty_port *tty_port = &up->port.state->port;
>  	struct dma_tx_state state;
> +	int copied, cnt, tmp;
>  	unsigned char *ptr;
> -	int copied;
>  
> -	dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr,
> -				dma->rx_size, DMA_FROM_DEVICE);
> +	if (data->rx_status == DMA_RX_SHUTDOWN)
> +		return;
>  
>  	dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
> +	cnt = dma->rx_size - state.residue;
> +	tmp = cnt;
>  
> -	if (data->rx_status == DMA_RX_SHUTDOWN)
> -		return;
> +	if ((data->rx_pos + cnt) > dma->rx_size)
> +		tmp = dma->rx_size - data->rx_pos;
>  
> -	if ((data->rx_pos + state.residue) <= dma->rx_size) {
> -		ptr = (unsigned char *)(data->rx_pos + dma->rx_buf);
> -		copied = tty_insert_flip_string(tty_port, ptr, state.residue);
> -	} else {
> -		ptr = (unsigned char *)(data->rx_pos + dma->rx_buf);
> -		copied = tty_insert_flip_string(tty_port, ptr,
> -						dma->rx_size - data->rx_pos);
> +	ptr = (unsigned char *)(data->rx_pos + dma->rx_buf);
> +	copied = tty_insert_flip_string(tty_port, ptr, tmp);
> +	data->rx_pos += tmp;
> +
> +	if (cnt > tmp) {
>  		ptr = (unsigned char *)(dma->rx_buf);
> -		copied += tty_insert_flip_string(tty_port, ptr,
> -				data->rx_pos + state.residue - dma->rx_size);
> +		tmp = cnt - tmp;
> +		copied += tty_insert_flip_string(tty_port, ptr, tmp);
> +		data->rx_pos = tmp;
>  	}
> +
>  	up->port.icount.rx += copied;
>  
>  	tty_flip_buffer_push(tty_port);
> @@ -96,9 +97,7 @@ static void mtk8250_dma_rx_complete(void *param)
>  static void mtk8250_rx_dma(struct uart_8250_port *up)
>  {
>  	struct uart_8250_dma *dma = up->dma;
> -	struct mtk8250_data *data = up->port.private_data;
>  	struct dma_async_tx_descriptor	*desc;
> -	struct dma_tx_state	 state;
>  
>  	desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
>  					   dma->rx_size, DMA_DEV_TO_MEM,
> @@ -113,12 +112,6 @@ static void mtk8250_rx_dma(struct uart_8250_port *up)
>  
>  	dma->rx_cookie = dmaengine_submit(desc);
>  
> -	dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
> -	data->rx_pos = state.residue;
> -
> -	dma_sync_single_for_device(dma->rxchan->device->dev, dma->rx_addr,
> -				   dma->rx_size, DMA_FROM_DEVICE);
> -
>  	dma_async_issue_pending(dma->rxchan);
>  }
>  
> @@ -131,13 +124,13 @@ static void mtk8250_dma_enable(struct uart_8250_port *up)
>  	if (data->rx_status != DMA_RX_START)
>  		return;
>  
> -	dma->rxconf.direction		= DMA_DEV_TO_MEM;
> -	dma->rxconf.src_addr_width	= dma->rx_size / 1024;
> -	dma->rxconf.src_addr		= dma->rx_addr;
> +	dma->rxconf.direction				= DMA_DEV_TO_MEM;

Direction field is deprecated, please do not use this anymore...

> +	dma->rxconf.src_port_window_size	= dma->rx_size;
> +	dma->rxconf.src_addr				= dma->rx_addr;
>  
> -	dma->txconf.direction		= DMA_MEM_TO_DEV;
> -	dma->txconf.dst_addr_width	= MTK_UART_TX_SIZE / 1024;
> -	dma->txconf.dst_addr		= dma->tx_addr;
> +	dma->txconf.direction				= DMA_MEM_TO_DEV;
> +	dma->txconf.dst_port_window_size	= UART_XMIT_SIZE;
> +	dma->txconf.dst_addr				= dma->tx_addr;
>  
>  	serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR |
>  		UART_FCR_CLEAR_XMIT);
> @@ -217,7 +210,7 @@ static void mtk8250_shutdown(struct uart_port *port)
>  	 * Mediatek UARTs use an extra highspeed register (UART_MTK_HIGHS)
>  	 *
>  	 * We need to recalcualte the quot register, as the claculation depends
> -	 * on the vaule in the highspeed register.
> +	 * on the value in the highspeed register.
>  	 *
>  	 * Some baudrates are not supported by the chip, so we use the next
>  	 * lower rate supported and update termios c_flag.
> -- 
> 1.7.9.5

-- 
~Vinod