| Message ID | 20180903215035.17265-4-linus.walleij@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | SPI 3WIRE fixes and highz turnaround | expand |
Hi Linus, On Mon, Sep 3, 2018 at 11:51 PM Linus Walleij <linus.walleij@linaro.org> wrote: > Some 3WIRE SPI devices require the host to insert a "high > impedance turnaround" essentially a clock pulse after high-impedance (English allows both, but since you use "turn-around") > switching the one line from output to input. > > This is needed to support the TPO TPG110 panel to use > the 3WIRE SPI bindings. > > Cc: devicetree@vger.kernel.org > Cc: Andrzej Hajda <a.hajda@samsung.com> > Cc: Lorenzo Bianconi <lorenzo.bianconi@redhat.com> > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Thanks for your patch! > --- a/Documentation/devicetree/bindings/spi/spi-bus.txt > +++ b/Documentation/devicetree/bindings/spi/spi-bus.txt > @@ -70,6 +70,10 @@ All slave nodes can contain the following optional properties: > - spi-cs-high - Empty property indicating device requires chip select > active high. > - spi-3wire - Empty property indicating device requires 3-wire mode. > +- spi-3wire-high-impedance-turnaround - Empty property indicating that a > + 3wire host need to insert a high impedance turn-around needs high-impedance > + clock cycle after turning the one output line into an > + input line. > - spi-lsb-first - Empty property indicating device requires LSB first mode. > - spi-tx-bus-width - The bus width (number of data wires) that is used for MOSI. > Defaults to 1 if not present. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt index 1f6e86f787ef..ee08be2894eb 100644 --- a/Documentation/devicetree/bindings/spi/spi-bus.txt +++ b/Documentation/devicetree/bindings/spi/spi-bus.txt @@ -70,6 +70,10 @@ All slave nodes can contain the following optional properties: - spi-cs-high - Empty property indicating device requires chip select active high. - spi-3wire - Empty property indicating device requires 3-wire mode. +- spi-3wire-high-impedance-turnaround - Empty property indicating that a + 3wire host need to insert a high impedance turn-around + clock cycle after turning the one output line into an + input line. - spi-lsb-first - Empty property indicating device requires LSB first mode. - spi-tx-bus-width - The bus width (number of data wires) that is used for MOSI. Defaults to 1 if not present.
Some 3WIRE SPI devices require the host to insert a "high impedance turnaround" essentially a clock pulse after switching the one line from output to input. This is needed to support the TPO TPG110 panel to use the 3WIRE SPI bindings. Cc: devicetree@vger.kernel.org Cc: Andrzej Hajda <a.hajda@samsung.com> Cc: Lorenzo Bianconi <lorenzo.bianconi@redhat.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- Documentation/devicetree/bindings/spi/spi-bus.txt | 4 ++++ 1 file changed, 4 insertions(+) -- 2.17.1