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spi: microchip-core: ensure TX and RX FIFOs are empty at start of a transfer

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While transmitting with rx_len == 0, the RX FIFO is not going to be
emptied in the interrupt handler. A subsequent transfer could then
read crap from the previous transfer out of the RX FIFO into the
start RX buffer. The core provides a register that will empty the RX and
TX FIFOs, so do that before each transfer.

Fixes: 9ac8d17694b6 ("spi: add support for microchip fpga spi controllers")
Signed-off-by: Steve Wilkins <steve.wilkins@raymarine.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://patch.msgid.link/20240715-flammable-provoke-459226d08e70@wendy
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Steve Wilkins 2024-07-15 12:13:56 +01:00 committed by Mark Brown
parent 3a5e762836
commit 9cf71eb0fa
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1 changed files with 4 additions and 0 deletions
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4
drivers/spi/spi-microchip-core.c
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@ -91,6 +91,8 @@
#define REG_CONTROL2 (0x28) #define REG_CONTROL2 (0x28)
#define REG_COMMAND (0x2c) #define REG_COMMAND (0x2c)
#define COMMAND_CLRFRAMECNT BIT(4) #define COMMAND_CLRFRAMECNT BIT(4)
#define COMMAND_TXFIFORST BIT(3)
#define COMMAND_RXFIFORST BIT(2)
#define REG_PKTSIZE (0x30) #define REG_PKTSIZE (0x30)
#define REG_CMD_SIZE (0x34) #define REG_CMD_SIZE (0x34)
#define REG_HWSTATUS (0x38) #define REG_HWSTATUS (0x38)
@ -496,6 +498,8 @@ static int mchp_corespi_transfer_one(struct spi_controller *host,
mchp_corespi_set_xfer_size(spi, (spi->tx_len > FIFO_DEPTH) mchp_corespi_set_xfer_size(spi, (spi->tx_len > FIFO_DEPTH)
? FIFO_DEPTH : spi->tx_len); ? FIFO_DEPTH : spi->tx_len);
mchp_corespi_write(spi, REG_COMMAND, COMMAND_RXFIFORST | COMMAND_TXFIFORST);
mchp_corespi_write(spi, REG_SLAVE_SELECT, spi->pending_slave_select); mchp_corespi_write(spi, REG_SLAVE_SELECT, spi->pending_slave_select);
while (spi->tx_len) while (spi->tx_len)