octeontx: fix mcp251x can controller

Update the can-mcp251x-convert-to-half-duplex-SPI patch to fix reception

Some SPI host controllers such as the Cavium Thunder TX do not support
full-duplex SPI. Using half-duplex transfers allows the driver to work
with those host controllers.

This patch fixes the fact that mcp251x_hw_rx_frame was still relying on
a full-duplex transfer where bits were being shifted on MOSI at the same time
as MISO. After splitting the transaction into a spi_write_then_read() care
must be taken to ignore the first byte.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>

target/linux/octeontx/patches-5.4/0003-can-mcp251x-convert-to-half-duplex-SPI.patch

@@ -1,20 +1,22 @@
-From 6edfb172ff1dd3cfc84c19790c245a4005474bb7 Mon Sep 17 00:00:00 2001
+From 097cc81ee5c15913ad330baffff2e3dea09bdad0 Mon Sep 17 00:00:00 2001
 From: Tim Harvey <tharvey@gateworks.com>
-Date: Tue, 25 Feb 2020 12:01:36 -0800
-Subject: [PATCH 03/12] can: mcp251x: convert to half-duplex SPI
+Date: Thu, 30 Aug 2018 15:16:08 -0700
+Subject: [PATCH] can: mcp251x: convert driver to half-duplex SPI
 
-Some SPI host controllers such as the Cavium Thunder do not support
+Some SPI host controllers such as the Cavium Thunder TX do not support
 full-duplex SPI. Using half-duplex transfers allows the driver to work
 with those host controllers.
 
 Signed-off-by: Tim Harvey <tharvey@gateworks.com>
 ---
- drivers/net/can/spi/mcp251x.c | 10 +++++-----
- 1 file changed, 5 insertions(+), 5 deletions(-)
+ drivers/net/can/spi/mcp251x.c | 15 ++++++++-------
+ 1 file changed, 8 insertions(+), 7 deletions(-)
 
+diff --git a/drivers/net/can/spi/mcp251x.c b/drivers/net/can/spi/mcp251x.c
+index bb20a9b..dc0574a 100644
 --- a/drivers/net/can/spi/mcp251x.c
 +++ b/drivers/net/can/spi/mcp251x.c
-@@ -291,23 +291,23 @@ static u8 mcp251x_read_reg(struct spi_de
+@@ -291,23 +291,23 @@ static u8 mcp251x_read_reg(struct spi_device *spi, u8 reg)
  	priv->spi_tx_buf[0] = INSTRUCTION_READ;
  	priv->spi_tx_buf[1] = reg;
  
@@ -43,3 +45,18 @@ Signed-off-by: Tim Harvey <tharvey@gateworks.com>
  }
  
  static void mcp251x_write_reg(struct spi_device *spi, u8 reg, u8 val)
+@@ -398,8 +398,9 @@ static void mcp251x_hw_rx_frame(struct spi_device *spi, u8 *buf,
+ 			buf[i] = mcp251x_read_reg(spi, RXBCTRL(buf_idx) + i);
+ 	} else {
+ 		priv->spi_tx_buf[RXBCTRL_OFF] = INSTRUCTION_READ_RXB(buf_idx);
+-		mcp251x_spi_trans(spi, SPI_TRANSFER_BUF_LEN);
+-		memcpy(buf, priv->spi_rx_buf, SPI_TRANSFER_BUF_LEN);
++		spi_write_then_read(spi, priv->spi_tx_buf, 1, priv->spi_rx_buf,
++				    SPI_TRANSFER_BUF_LEN);
++		memcpy(buf + 1, priv->spi_rx_buf, SPI_TRANSFER_BUF_LEN - 1);
+ 	}
+ }
+ 
+-- 
+2.7.4
+