From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/drivers/spi/spi-gpio.c | 16 +++++++++++++---
1 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/kernel/drivers/spi/spi-gpio.c b/kernel/drivers/spi/spi-gpio.c
index 0584f4d..3ffdab6 100644
--- a/kernel/drivers/spi/spi-gpio.c
+++ b/kernel/drivers/spi/spi-gpio.c
@@ -244,9 +244,19 @@
if (output)
return gpiod_direction_output(spi_gpio->mosi, 1);
- ret = gpiod_direction_input(spi_gpio->mosi);
- if (ret)
- return ret;
+ /*
+ * Only change MOSI to an input if using 3WIRE mode.
+ * Otherwise, MOSI could be left floating if there is
+ * no pull resistor connected to the I/O pin, or could
+ * be left logic high if there is a pull-up. Transmitting
+ * logic high when only clocking MISO data in can put some
+ * SPI devices in to a bad state.
+ */
+ if (spi->mode & SPI_3WIRE) {
+ ret = gpiod_direction_input(spi_gpio->mosi);
+ if (ret)
+ return ret;
+ }
/*
* Send a turnaround high impedance cycle when switching
* from output to input. Theoretically there should be
--
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