diff mbox

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

Message ID 1475852194-27690-1-git-send-email-tthayer@opensource.altera.com
State New, archived
Headers show

Commit Message

tthayer@opensource.altera.com Oct. 7, 2016, 2:56 p.m. UTC
From: Thor Thayer <tthayer@opensource.altera.com>

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@opensource.altera.com>
---
v2  Add to SPI framework - add bindings.
---
 Documentation/devicetree/bindings/spi/spi-bus.txt |    1 +
 1 file changed, 1 insertion(+)

Comments

Geert Uytterhoeven Oct. 7, 2016, 7:33 p.m. UTC | #1
On Fri, Oct 7, 2016 at 4:56 PM,  <tthayer@opensource.altera.com> wrote:
> From: Thor Thayer <tthayer@opensource.altera.com>
>
> 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@opensource.altera.com>
> ---
> 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.

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
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tthayer@opensource.altera.com Oct. 7, 2016, 8:01 p.m. UTC | #2
On 10/07/2016 02:33 PM, Geert Uytterhoeven wrote:
> On Fri, Oct 7, 2016 at 4:56 PM,  <tthayer@opensource.altera.com> wrote:
>> From: Thor Thayer <tthayer@opensource.altera.com>
>>
>> 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@opensource.altera.com>
>> ---
>> 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!

> 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
>
--
To unsubscribe from this list: send the line "unsubscribe linux-spi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
diff mbox

Patch

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).