linux-kernel - Re: [PATCH v1 07/12] serial: 8250_dma: adjust DMA address of the UART

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Date:	Thu, 7 Apr 2016 17:24:59 -0700
From:	Peter Hurley <peter@...leysoftware.com>
To:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:	Vinod Koul <vinod.koul@...el.com>, linux-kernel@...r.kernel.org,
	dmaengine@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	ismo.puustinen@...el.com,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	linux-serial@...r.kernel.org
Subject: Re: [PATCH v1 07/12] serial: 8250_dma: adjust DMA address of the UART

On 04/07/2016 01:37 PM, Andy Shevchenko wrote:
> Some UARTs, e.g. one is used in Intel Quark, have a different address base for
> DMA operations. Introduce an additional field in struct uart_8250_dma to cover
> those cases.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/tty/serial/8250/8250.h     | 2 ++
>  drivers/tty/serial/8250/8250_dma.c | 5 +++--
>  2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
> index 047a7ba..040deb2 100644
> --- a/drivers/tty/serial/8250/8250.h
> +++ b/drivers/tty/serial/8250/8250.h
> @@ -31,6 +31,8 @@ struct uart_8250_dma {
>  	struct dma_chan		*rxchan;
>  	struct dma_chan		*txchan;
>  
> +	phys_addr_t		dma_addr;
> +

Let's add separate rx and tx device addrs.


>  	dma_addr_t		rx_addr;
>  	dma_addr_t		tx_addr;
>  
> diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
> index b134bec..a314492 100644
> --- a/drivers/tty/serial/8250/8250_dma.c
> +++ b/drivers/tty/serial/8250/8250_dma.c
> @@ -164,16 +164,17 @@ int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
>  int serial8250_request_dma(struct uart_8250_port *p)
>  {
>  	struct uart_8250_dma	*dma = p->dma;
> +	phys_addr_t dma_addr = dma->dma_addr ? dma->dma_addr : p->port.mapbase;
>  	dma_cap_mask_t		mask;
>  
>  	/* Default slave configuration parameters */
>  	dma->rxconf.direction		= DMA_DEV_TO_MEM;
>  	dma->rxconf.src_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;
> -	dma->rxconf.src_addr		= p->port.mapbase + UART_RX;
> +	dma->rxconf.src_addr		= dma_addr + UART_RX;
>  
>  	dma->txconf.direction		= DMA_MEM_TO_DEV;
>  	dma->txconf.dst_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;
> -	dma->txconf.dst_addr		= p->port.mapbase + UART_TX;
> +	dma->txconf.dst_addr		= dma_addr + UART_TX;
>  
>  	dma_cap_zero(mask);
>  	dma_cap_set(DMA_SLAVE, mask);
>