linux-kernel - [PATCH v1 2/4] spi: npcm-pspi: improve spi transfer performance

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Date:   Wed, 15 Jan 2020 18:22:59 +0200
From:   Tomer Maimon <tmaimon77@...il.com>
To:     broonie@...nel.org, robh+dt@...nel.org, mark.rutland@....com,
        avifishman70@...il.com, tali.perry1@...il.com, venture@...gle.com,
        yuenn@...gle.com, benjaminfair@...gle.com
Cc:     linux-spi@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, openbmc@...ts.ozlabs.org,
        Tomer Maimon <tmaimon77@...il.com>
Subject: [PATCH v1 2/4] spi: npcm-pspi: improve spi transfer performance

Improving spi 8 bit per word mode transfer performance
by using 16 bit per word transfer and receive when the data
length is even and larger than one.

Signed-off-by: Tomer Maimon <tmaimon77@...il.com>
---
 drivers/spi/spi-npcm-pspi.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/spi/spi-npcm-pspi.c b/drivers/spi/spi-npcm-pspi.c
index c74611abe2a9..eac7ba18b4b9 100644
--- a/drivers/spi/spi-npcm-pspi.c
+++ b/drivers/spi/spi-npcm-pspi.c
@@ -178,6 +178,13 @@ static void npcm_pspi_setup_transfer(struct spi_device *spi,
 		priv->mode = spi->mode;
 	}
 
+	/*
+	 * If transfer is even length, and 8 bits per word transfer,
+	 * then implement 16 bits-per-word transfer.
+	 */
+	if (priv->bits_per_word == 8 && !(t->len & 0x1))
+		t->bits_per_word = 16;
+
 	if (!priv->is_save_param || priv->bits_per_word != t->bits_per_word) {
 		npcm_pspi_set_transfer_size(priv, t->bits_per_word);
 		priv->bits_per_word = t->bits_per_word;
-- 
2.22.0