[v2,14/19] spi: mpc8xxx: Document LEN setting better
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Message ID 20190428202854.8590-15-jagan@amarulasolutions.com
State New
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Series
  • [v2,01/19] spi: mpc8xxx: Use short type names
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Commit Message

Jagan Teki April 28, 2019, 8:28 p.m. UTC 
From: Mario Six <mario.six@gdsys.cc>

Instead of having a table right before the code implementing the length
setting for documentation, have inline comments for the if branches
actually implementing the length setting described table's entries
(which is readable thanks to the set_char_len function).

Signed-off-by: Mario Six <mario.six@gdsys.cc>
---
 drivers/spi/mpc8xxx_spi.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

Patch
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diff --git a/drivers/spi/mpc8xxx_spi.c b/drivers/spi/mpc8xxx_spi.c
index 63d956a295..1dd5bd9799 100644
--- a/drivers/spi/mpc8xxx_spi.c
+++ b/drivers/spi/mpc8xxx_spi.c
@@ -119,21 +119,15 @@  int spi_xfer(struct spi_slave *slave, uint bitlen, const void *dout, void *din,
 		/* Shift data so it's msb-justified */
 		tmpdout = *(u32 *)dout >> (32 - xfer_bitlen);
 
-		/* The LEN field of the SPMODE register is set as follows:
-		 *
-		 * Bit length             setting
-		 * len <= 4               3
-		 * 4 < len <= 16          len - 1
-		 * len > 16               0
-		 */
-
 		clrbits_be32(&spi->mode, SPI_MODE_EN);
 
-		if (bitlen <= 4)
+		/* Set up length for this transfer */
+
+		if (bitlen <= 4) /* 4 bits or less */
 			set_char_len(spi, 3);
-		else if (bitlen <= 16)
+		else if (bitlen <= 16) /* at most 16 bits */
 			set_char_len(spi, bitlen - 1);
-		else
+		else /* more than 16 bits -> full 32 bit transfer */
 			set_char_len(spi, 0);
 
 		if (bitlen > 16) {