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i2c: tegra: Rename I2C_PIO_MODE_MAX_LEN to I2C_PIO_MODE_PREFERRED_LEN

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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: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Dmitry Osipenko 2020-01-14 04:34:39 +03:00 committed by Wolfram Sang
parent ede2299f71
commit ae6028a655
1 changed files with 6 additions and 5 deletions
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11
drivers/i2c/busses/i2c-tegra.c
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@ -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);