Guide users to maintain the proper balance between native and GPIO chip selects. Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> --- Documentation/devicetree/bindings/spi/sh-msiof.txt | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/Documentation/devicetree/bindings/spi/sh-msiof.txt b/Documentation/devicetree/bindings/spi/sh-msiof.txt index bc8c16a6cfc82685..80710f0f04489174 100644 --- a/Documentation/devicetree/bindings/spi/sh-msiof.txt +++ b/Documentation/devicetree/bindings/spi/sh-msiof.txt @@ -41,6 +41,16 @@ Optional properties: 0: MSIOF_SYNC 1: MSIOF_SS1 2: MSIOF_SS2 + Hardware limitations related to chip selects: + - Native chip selects are always deasserted in + between transfers that are part of the same + message. Use cs-gpios to work around this. + - All slaves using native chip selects must use the + same spi-cs-high configuration. Use cs-gpios to + work around this. + - When using GPIO chip selects, at least one native + chip select must be left unused, as it will be + driven anyway. - dmas : Must contain a list of two references to DMA specifiers, one for transmission, and one for reception. -- 2.7.4
