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| author | Geert Uytterhoeven | 2017-12-13 20:05:13 +0100 |
|---|---|---|
| committer | Mark Brown | 2017-12-14 12:46:19 +0100 |
| commit | c99182f73cce7926c623b5c1c0ff0b7954ac8d81 (patch) | |
| tree | 2fa4929e839e85bc2b3d114f7b44dc706ef48cc2 /Documentation/devicetree/bindings/spi | |
| parent | spi: sh-msiof: Implement cs-gpios configuration (diff) | |
| download | kernel-qcow2-linux-c99182f73cce7926c623b5c1c0ff0b7954ac8d81.tar.gz kernel-qcow2-linux-c99182f73cce7926c623b5c1c0ff0b7954ac8d81.tar.xz kernel-qcow2-linux-c99182f73cce7926c623b5c1c0ff0b7954ac8d81.zip | |
spi: sh-msiof: Document hardware limitations related to chip selects
Guide users to maintain the proper balance between native and GPIO chip
selects.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'Documentation/devicetree/bindings/spi')
| -rw-r--r-- | Documentation/devicetree/bindings/spi/sh-msiof.txt | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/spi/sh-msiof.txt b/Documentation/devicetree/bindings/spi/sh-msiof.txt index bc8c16a6cfc8..80710f0f0448 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. |