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* [PATCH] spi: gpio: Add SPI_MASTER_GPIO_SS flag
@ 2019-07-16 20:46 Linus Walleij
  2019-07-17 17:58 ` Applied "spi: gpio: Add SPI_MASTER_GPIO_SS flag" to the spi tree Mark Brown
  0 siblings, 1 reply; 2+ messages in thread
From: Linus Walleij @ 2019-07-16 20:46 UTC (permalink / raw)
  To: Mark Brown, linux-spi; +Cc: linux-gpio, Linus Walleij, Andrey Smirnov

The GPIO SPI master has some code in its local CS
callback to set the initial sck GPIO value. This was
lost in the commit converting it to use SPI core
GPIO handling as this callback isn't called if the
internal GPIO handling is active.

Add the special SPI_MASTER_GPIO_SS to ascertain it
gets called anyway so we get the initial SCK setting
right. There is some platform provided GPIO handling
there as well but this will be skipped as the cs_gpios
will be NULL.

My test targets seem not to care about the initial
SCK value so I am uncertain if this is a regression,
but to preserve the previous semantic we better do

Cc: Andrey Smirnov <>
Fixes: 249e2632dcd0 ("spi: gpio: Don't request CS GPIO in DT use-case")
Signed-off-by: Linus Walleij <>
 drivers/spi/spi-gpio.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/spi/spi-gpio.c b/drivers/spi/spi-gpio.c
index eca9d52ecf65..9eb82150666e 100644
--- a/drivers/spi/spi-gpio.c
+++ b/drivers/spi/spi-gpio.c
@@ -410,6 +410,12 @@ static int spi_gpio_probe(struct platform_device *pdev)
 	bb = &spi_gpio->bitbang;
 	bb->master = master;
+	/*
+	 * There is some additional business, apart from driving the CS GPIO
+	 * line, that we need to do on selection. This makes the local
+	 * callback for chipselect always get called.
+	 */
+	master->flags |= SPI_MASTER_GPIO_SS;
 	bb->chipselect = spi_gpio_chipselect;
 	bb->set_line_direction = spi_gpio_set_direction;

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2019-07-17 17:58 UTC | newest]

Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
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2019-07-16 20:46 [PATCH] spi: gpio: Add SPI_MASTER_GPIO_SS flag Linus Walleij
2019-07-17 17:58 ` Applied "spi: gpio: Add SPI_MASTER_GPIO_SS flag" to the spi tree Mark Brown

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