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Date: Mon, 1 Mar 2010 10:46:00 -0800
From: Tony Lindgren <tony@atomide.com>
To: "Govindraj.R" <govindraj.raja@ti.com>
Cc: Greg KH <greg@kroah.com>, linux-serial@vger.kernel.org,
       linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org,
       Kevin Hilman <khilman@deeprootsystems.com>,
       Olof Johansson <olof@lixom.net>
Subject: Re: [PATCH] serial: Add OMAP high-speed UART driver.
Message-ID: <20100301184600.GC3389@atomide.com>
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* Govindraj.R <govindraj.raja@ti.com> [100301 06:40]:
> --- /dev/null
> +++ b/drivers/serial/omap-serial.c
> +
> +static void serial_omap_stop_tx(struct uart_port *port)
> +{
> +	struct uart_omap_port *up = (struct uart_omap_port *)port;
> +
> +	if (up->use_dma &&
> +		up->uart_dma.tx_dma_channel != OMAP_UART_DMA_CH_FREE) {
> +		/*
> +		 * Check if dma is still active . If yes do nothing,

Looks like an extra space here before the period above.

...

> +static int serial_omap_start_rxdma(struct uart_omap_port *up)
> +{
> +	int ret = 0;
> +
> +	if (up->uart_dma.rx_dma_channel == -1) {
> +		ret = omap_request_dma(up->uart_dma.uart_dma_rx,
> +				"UART Rx DMA",
> +				(void *)uart_rx_dma_callback, up,
> +				&(up->uart_dma.rx_dma_channel));
> +		if (ret < 0)
> +			return ret;
> +
> +		omap_set_dma_src_params(up->uart_dma.rx_dma_channel, 0,
> +				OMAP_DMA_AMODE_CONSTANT,
> +				up->uart_dma.uart_base, 0, 0);
> +		omap_set_dma_dest_params(up->uart_dma.rx_dma_channel, 0,
> +				OMAP_DMA_AMODE_POST_INC,
> +				up->uart_dma.rx_buf_dma_phys, 0, 0);
> +		omap_set_dma_transfer_params(up->uart_dma.rx_dma_channel,
> +				OMAP_DMA_DATA_TYPE_S8,
> +				up->uart_dma.rx_buf_size, 1,
> +				OMAP_DMA_SYNC_ELEMENT,
> +				up->uart_dma.uart_dma_rx, 0);
> +	}
> +	up->uart_dma.prev_rx_dma_pos = up->uart_dma.rx_buf_dma_phys;
> +	if (cpu_is_omap44xx())
> +		omap_writel(0, OMAP44XX_DMA4_BASE
> +			+ OMAP_DMA4_CDAC(up->uart_dma.rx_dma_channel));
> +	else
> +		omap_writel(0, OMAP34XX_DMA4_BASE
> +			+ OMAP_DMA4_CDAC(up->uart_dma.rx_dma_channel));

NAK. Please don't use omap_read/write for for new code. And do not
tinker with the omap hardware registers directly in the driver.

This needs to be done properly in arch/arm/plat-omap/dma.c instead.

We really don't want drivers tinkering with the omap hardware
registers directly except for the driver block registers.

Regards,

Tony