arm64: dts: rk3399-box: compatible for rev2 board which cpu_b's vdd gpio is different

[firefly-linux-kernel-4.4.55.git] / Documentation / blackfin / bfin-spi-notes.txt

diff --git a/Documentation/blackfin/bfin-spi-notes.txt b/Documentation/blackfin/bfin-spi-notes.txt
index 556fa877f2e816a143113b880db1cf1c727285be..eae6eaf2a09dad1967e25ea39611bc2da8034784 100644 (file)
--- a/Documentation/blackfin/bfin-spi-notes.txt
+++ b/Documentation/blackfin/bfin-spi-notes.txt
@@ -9,6 +9,8 @@ the entire SPI transfer. - And not just bits_per_word duration.
 In most cases you can utilize SPI MODE_3 instead of MODE_0 to work-around this
 behavior. If your SPI slave device in question requires SPI MODE_0 or MODE_2
 timing, you can utilize the GPIO controlled SPI Slave Select option instead.
+In this case, you should use GPIO based CS for all of your slaves and not just
+the ones using mode 0 or 2 in order to guarantee correct CS toggling behavior.
 
 You can even use the same pin whose peripheral role is a SSEL,
 but use it as a GPIO instead.