| Message ID | 1513191913-10612-5-git-send-email-geert+renesas@glider.be |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | spi: sh-msiof: Multi-slave enhancements | expand |
On Wed, Dec 13, 2017 at 08:05:13PM +0100, Geert Uytterhoeven wrote: > + 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. Ideally the driver would be generating an error when it sees multi-transfer messages.
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.
Guide users to maintain the proper balance between native and GPIO chip selects. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- Documentation/devicetree/bindings/spi/sh-msiof.txt | 10 ++++++++++ 1 file changed, 10 insertions(+)