From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Harvey Subject: [PATCH] can: mcp251x: convert to half-duplex SPI Date: Tue, 25 Feb 2020 10:35:34 -0800 Message-ID: <1582655734-20890-1-git-send-email-tharvey@gateworks.com> Return-path: Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org, linux-can@vger.kernel.org, Wolfgang Grandegger , Marc Kleine-Budde Cc: =?UTF-8?q?Timo=20Schl=C3=BC=C3=9Fler?= , Andy Shevchenko , Tim Harvey List-Id: linux-can.vger.kernel.org Some SPI host controllers such as the Cavium Thunder do not support full-duplex SPI. Using half-duplex transfers allows the driver to work with those host controllers. Signed-off-by: Tim Harvey --- drivers/net/can/spi/mcp251x.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/net/can/spi/mcp251x.c b/drivers/net/can/spi/mcp251x.c index 5009ff2..840c31c 100644 --- a/drivers/net/can/spi/mcp251x.c +++ b/drivers/net/can/spi/mcp251x.c @@ -290,23 +290,23 @@ static u8 mcp251x_read_reg(struct spi_device *spi, u8 reg) priv->spi_tx_buf[0] = INSTRUCTION_READ; priv->spi_tx_buf[1] = reg; - mcp251x_spi_trans(spi, 3); - val = priv->spi_rx_buf[2]; + spi_write_then_read(spi, priv->spi_tx_buf, 2, &val, 1); return val; } static void mcp251x_read_2regs(struct spi_device *spi, u8 reg, u8 *v1, u8 *v2) { + u8 val[4] = {0}; struct mcp251x_priv *priv = spi_get_drvdata(spi); priv->spi_tx_buf[0] = INSTRUCTION_READ; priv->spi_tx_buf[1] = reg; - mcp251x_spi_trans(spi, 4); + spi_write_then_read(spi, priv->spi_tx_buf, 2, val, 2); - *v1 = priv->spi_rx_buf[2]; - *v2 = priv->spi_rx_buf[3]; + *v1 = val[0]; + *v2 = val[1]; } static void mcp251x_write_reg(struct spi_device *spi, u8 reg, u8 val) -- 2.7.4