From c43082d284fa15079c3ca22583fd76f50fe4e5d4 Mon Sep 17 00:00:00 2001 From: Mirko Vogt Date: Mon, 14 Jun 2021 16:45:07 +0200 Subject: [PATCH] spi: spi-sun6i: Fix chipselect/clock bug [ Upstream commit 0d7993b234c9fad8cb6bec6adfaa74694ba85ecb ] The current sun6i SPI implementation initializes the transfer too early, resulting in SCK going high before the transfer. When using an additional (gpio) chipselect with sun6i, the chipselect is asserted at a time when clock is high, making the SPI transfer fail. This is due to SUN6I_GBL_CTL_BUS_ENABLE being written into SUN6I_GBL_CTL_REG at an early stage. Moving that to the transfer function, hence, right before the transfer starts, mitigates that problem. Fixes: 3558fe900e8af (spi: sunxi: Add Allwinner A31 SPI controller driver) Signed-off-by: Mirko Vogt Signed-off-by: Ralf Schlatterbeck Link: https://lore.kernel.org/r/20210614144507.y3udezjfbko7eavv@runtux.com Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- drivers/spi/spi-sun6i.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi-sun6i.c b/drivers/spi/spi-sun6i.c index 19238e1..803d92f 100644 --- a/drivers/spi/spi-sun6i.c +++ b/drivers/spi/spi-sun6i.c @@ -290,6 +290,10 @@ static int sun6i_spi_transfer_one(struct spi_master *master, } sun6i_spi_write(sspi, SUN6I_CLK_CTL_REG, reg); + /* Finally enable the bus - doing so before might raise SCK to HIGH */ + reg = sun6i_spi_read(sspi, SUN6I_GBL_CTL_REG); + reg |= SUN6I_GBL_CTL_BUS_ENABLE; + sun6i_spi_write(sspi, SUN6I_GBL_CTL_REG, reg); /* Setup the transfer now... */ if (sspi->tx_buf) @@ -398,7 +402,7 @@ static int sun6i_spi_runtime_resume(struct device *dev) } sun6i_spi_write(sspi, SUN6I_GBL_CTL_REG, - SUN6I_GBL_CTL_BUS_ENABLE | SUN6I_GBL_CTL_MASTER | SUN6I_GBL_CTL_TP); + SUN6I_GBL_CTL_MASTER | SUN6I_GBL_CTL_TP); return 0; -- 2.7.4