device initialization
The situation has been observed that on the RPI after a reboot the
GPIOs used for chip-selects are set to low when pinctl finishes setting
up the direction of the pins.
This can negatively impact the spi-bus and inhibit propper device
detection.
This (incomplete) code pulls the CS high to avoid the situation in the
common case of "normal" CS-priority - it still needs a revisit to get
the reverse polarity cases right as well.
A variation of this probably should get moved into spi_register_master
to fix this for other spi-controller as well.
Signed-off-by: Martin Sperl <ker...@martin.sperl.org>
Tested-by: Martin Sperl <ker...@martin.sperl.org>
---
drivers/spi/spi-bcm2835.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
Applies against spi - topic/bcm2835.
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 1d731b8..b6825a4 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -349,6 +349,26 @@ static int bcm2835_spi_setup(struct spi_device *spi)
return -EINVAL;
}
+static void bcm2835_spi_initialsetup_gpio(struct spi_master *master)
+{
+ int i;
+ bool level;
+
+ if (!master->cs_gpios)
+ return;
+
+ for (i = 0; i < master->num_chipselect; i++) {
+ if (gpio_is_valid(master->cs_gpios[i])) {
+ /* actually we need to figure out the
+ * configured CSPOL of that device here,
+ * not sure how to do that...
+ */
+ level = true;
+ gpio_set_value(master->cs_gpios[i], level);
+ }
+ }
+}
+
static int bcm2835_spi_probe(struct platform_device *pdev)
{
struct spi_master *master;
@@ -414,6 +434,9 @@ static int bcm2835_spi_probe(struct platform_device *pdev)
goto out_clk_disable;
}
+ /* set GPIO-CS to disabled */
+ bcm2835_spi_initialsetup_gpio(master);
+
return 0;
out_clk_disable:
--
1.7.10.4
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