Applied "spi: sh-msiof: Reduce the number of times write to and perform the transmission from FIFO" to the spi tree

[Mark Brown <broonie@xxxxxxxxxx>]

The patch

   spi: sh-msiof: Reduce the number of times write to and perform the transmission from FIFO

has been applied to the spi tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 916d9802e4b0723c1e4650e58e04c0259c14b85c Mon Sep 17 00:00:00 2001
From: Hoan Nguyen An <na-hoan@xxxxxxxxxxx>
Date: Thu, 20 Dec 2018 17:48:42 +0900
Subject: [PATCH] spi: sh-msiof: Reduce the number of times write to and
 perform the transmission from FIFO

The current state of the spi-sh-msiof, in master transfer mode: if t-> bits_per_word <= 8,
if the data length is divisible by 4 ((len & 3) = 0), the length of each word will be 32 bits
In case of data length can not be divisible by 4 ((len & 3) != 0), always set each word to be
8 bits, this will increase the number of times that write to FIFO, increasing the number of
times it should be transmitted. Assume that the number of bytes of data length more than 64 bytes,
each transmission will write 64 times into the TFDR then transmit, a maximum one-time
transmission will transmit 64 bytes if each word is 8 bits long.

Switch to setting if t->bits_per_word <= 8, the word length will be 32 bits although the data
length is not divisible by 4, then if leftover, will transmit the balance and the length of each
words is 1 byte. The maximum each can transmit up to 64 x 4 (Data Size = 32 bits (4 bytes)) = 256 bytes.
TMDR2 : Bits 28 to 24  BITLEN1[4:0] Data Size (8 to 32 bits)
        Bits 23 to 16  WDLEN1[7:0]  Word Count (1 to 64 words)

Signed-off-by: Hoan Nguyen An <na-hoan@xxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
 drivers/spi/spi-sh-msiof.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index d495d8604397..d14b407cc800 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -977,7 +977,7 @@ static int sh_msiof_transfer_one(struct spi_master *master,
 			return 0;
 	}
 
-	if (bits <= 8 && len > 15 && !(len & 3)) {
+	if (bits <= 8 && len > 15) {
 		bits = 32;
 		swab = true;
 	} else {
@@ -1038,6 +1038,14 @@ static int sh_msiof_transfer_one(struct spi_master *master,
 		if (rx_buf)
 			rx_buf += n * bytes_per_word;
 		words -= n;
+
+		if (words == 0 && (len % bytes_per_word)) {
+			words = len % bytes_per_word;
+			bits = t->bits_per_word;
+			bytes_per_word = 1;
+			tx_fifo = sh_msiof_spi_write_fifo_8;
+			rx_fifo = sh_msiof_spi_read_fifo_8;
+		}
 	}
 
 	return 0;
-- 
2.20.1