linux-kernel - [PATCH v1 2/3] i2c: tegra: Rename I2C_PIO_MODE_MAX_LEN to I2C_PIO_MODE_PREFERRED

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Date:   Fri, 13 Dec 2019 02:34:27 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Wolfram Sang <wsa@...-dreams.de>
Cc:     linux-i2c@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v1 2/3] 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.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 drivers/i2c/busses/i2c-tegra.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 799c343571bc..b3ecdd87e91f 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -130,11 +130,10 @@
 #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.
+ * Up to 32 bytes, controller will use PIO mode, above this, controller will
+ * use DMA to fill FIFO. MAX PIO length is 20 bytes (excluding packet header).
  */
-#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.
@@ -1105,7 +1104,7 @@ 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);
-- 
2.24.0