Re: [PATCHv2 1/2] Documentation: dt: spi: Add GPIO Slave Select Parameter

From: Thor Thayer
Date: Fri Oct 07 2016 - 15:55:49 EST

On 10/07/2016 02:33 PM, Geert Uytterhoeven wrote:
On Fri, Oct 7, 2016 at 4:56 PM, <tthayer@xxxxxxxxxxxxxxxxxxxxx> wrote:
From: Thor Thayer <tthayer@xxxxxxxxxxxxxxxxxxxxx>

Some SPI masters require the slave to be selected before a
transaction can occur - even in the case of GPIO chip select.

This patch adds a GPIO slave select parameter to indicate
the slave needs to be selected in the GPIO CS case.

Signed-off-by: Thor Thayer <tthayer@xxxxxxxxxxxxxxxxxxxxx>
v2 Add to SPI framework - add bindings.
Documentation/devicetree/bindings/spi/spi-bus.txt | 1 +
1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt
index 4b1d6e7..3a006bc 100644
--- a/Documentation/devicetree/bindings/spi/spi-bus.txt
+++ b/Documentation/devicetree/bindings/spi/spi-bus.txt
@@ -24,6 +24,7 @@ support describing the chip select layout.
Optional properties:
- cs-gpios - gpios chip select.
- num-cs - total number of chipselects.
+- gpio-ss - use internal slave select with gpio chip select.

If cs-gpios is used the number of chip selects will be increased automatically
with max(cs-gpios > hw cs).

To me, this looks more like a new flag the SPI controller driver should
set in spi_master.flags, instead of a DT property.

Yes, I see your point since this is SPI master specific. I'll respin as you suggest.

Thanks for reviewing!



Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

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