Commit ae6028a6 authored by Dmitry Osipenko's avatar Dmitry Osipenko Committed by Wolfram Sang
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i2c: tegra: Rename I2C_PIO_MODE_MAX_LEN to I2C_PIO_MODE_PREFERRED_LEN 



DMA is preferred for a larger transfers, while PIO is preferred for a
smaller transfers to avoid unnecessary DMA overhead. There is no strict
size limitations for the PIO-mode transfers, so let's rename the constant
for clarity.

Tested-by: default avatarThierry Reding <treding@nvidia.com>
Signed-off-by: default avatarDmitry Osipenko <digetx@gmail.com>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent ede2299f

drivers/i2c/busses/i2c-tegra.c

+6 −5
Original line number Diff line number Diff line
@@ -131,11 +131,12 @@ 
#define I2C_PACKET_HEADER_SIZE			12



/*

 * Upto I2C_PIO_MODE_MAX_LEN bytes, controller will use PIO mode,

 * above this, controller will use DMA to fill FIFO.

 * MAX PIO len is 20 bytes excluding packet header.

 * I2C Controller will use PIO mode for transfers up to 32 bytes in order to

 * avoid DMA overhead, otherwise external APB DMA controller will be used.

 * Note that the actual MAX PIO length is 20 bytes because 32 bytes include

 * I2C_PACKET_HEADER_SIZE.

 */

#define I2C_PIO_MODE_MAX_LEN			32

#define I2C_PIO_MODE_PREFERRED_LEN		32



/*

 * msg_end_type: The bus control which need to be send at end of transfer.
@@ -1110,7 +1111,7 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev, 
		xfer_size = msg->len + I2C_PACKET_HEADER_SIZE;



	xfer_size = ALIGN(xfer_size, BYTES_PER_FIFO_WORD);

	i2c_dev->is_curr_dma_xfer = (xfer_size > I2C_PIO_MODE_MAX_LEN) &&

	i2c_dev->is_curr_dma_xfer = (xfer_size > I2C_PIO_MODE_PREFERRED_LEN) &&

				    i2c_dev->dma_buf &&

				    !i2c_dev->is_curr_atomic_xfer;

	tegra_i2c_config_fifo_trig(i2c_dev, xfer_size);

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