Re: [PATCH v4 2/4] pinctrl: Add pinctrl binding for Broadcom Capri SoCs

[Sherman Yin <syin@broadcom.com>]

On 14-01-07 09:15 AM, Linus Walleij wrote:
> On Sat, Dec 21, 2013 at 3:13 AM, Sherman Yin <syin@broadcom.com> wrote:
>> +Optional Properties (for standard pins):
>> +
>> +- function:                    String. Specifies the pin mux selection. Values
>> +                               must be one of: "alt1", "alt2", "alt3", "alt4"
>> +- input-schmitt-enable:                No arguments. Enable schmitt-trigger mode.
>> +- input-schmitt-disable:       No arguments. Disable schmitt-trigger mode.
>> +- bias-pull-up:                        No arguments. Pull up on pin.
>> +- bias-pull-down:              No arguments. Pull down on pin.
>> +- bias-disable:                        No arguments. Disable pin bias.
>> +- slew-rate:                   Integer. Meaning depends on configured pin mux:
>> +                               *_SCL or *_SDA:
>> +                                       0: Standard(100kbps)& Fast(400kbps) mode
>> +                                       1: Highspeed (3.4Mbps) mode
>> +                               IC_DM or IC_DP:
>> +                                       0: normal slew rate
>> +                                       1: fast slew rate
>> +                               Otherwise:
>> +                                       0: fast slew rate
>> +                                       1: normal slew rate
>> +- input-enable:                        No arguements. Enable input (does not affect
>> +                               output.)
>> +- input-disable:               No arguements. Disable input (does not affect
>> +                               output.)
>> +- drive-strength:              Integer. Drive strength in mA.  Valid values are
>> +                               2, 4, 6, 8, 10, 12, 14, 16 mA.
>
> Also patch
> Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
> Since you're adding generic properties.

Please note that I removed from this patchset the patch that you've 
merged to your for-next branch already:

https://git.kernel.org/cgit/linux/kernel/git/linusw/linux-pinctrl.git/commit/?h=for-next&id=8ba3f4d00078e7a49c60c0bd6298f29402c3a0a0

Is that what you wanted to see in pinctrl-bindings.txt, or is there 
something else you want to see added to that txt file?  I didn't want to 
add the description of slew-rate arguments there because this is 
capri-specific.  I'm not quite sure what else to add.


>> +Optional Properties (for I2C pins):
>> +
>> +- function:                    String. Specifies the pin mux selection. Values
>> +                               must be one of: "alt1", "alt2", "alt3", "alt4"
>> +- bias-pull-up:                        Integer. Pull up strength in Ohm. There are 3
>> +                               pull-up resisitors (1.2k, 1.8k, 2.7k) available
>> +                               in parallel for I2C pins, so the valid values
>> +                               are: 568, 720, 831, 1080, 1200, 1800, 2700 Ohm.
>
> Also patch
> Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt

That doc already says bias-pull-up is specified in Ohm, and the specific 
values are chip-specific, so I don't think they should be mentioned there.

>> +- bias-disable:                        No arguments. Disable pin bias.
>> +- slew-rate:                   Integer. Meaning depends on configured pin mux:
>> +                               *_SCL or *_SDA:
>> +                                       0: Standard(100kbps)& Fast(400kbps) mode
>> +                                       1: Highspeed (3.4Mbps) mode
>> +                               IC_DM or IC_DP:
>> +                                       0: normal slew rate
>> +                                       1: fast slew rate
>> +                               Otherwise:
>> +                                       0: fast slew rate
>> +                                       1: normal slew rate
>
> Hm that does not seem generic though, so let's not add this to the
> generic bindings.
>
>> +- input-enable:                        No arguements. Enable input (does not affect
>> +                               output.)
>> +- input-disable:               No arguements. Disable input (does not affect
>> +                               output.)
>> +
>> +Optional Properties (for HDMI pins):
>> +
>> +- function:                    String. Specifies the pin mux selection. Values
>> +                               must be one of: "alt1", "alt2", "alt3", "alt4"
>> +- slew-rate:                   Integer. Controls slew rate.
>> +                                       0: Standard(100kbps)& Fast(400kbps) mode
>> +                                       1: Highspeed (3.4Mbps) mode
>
> Hmmmm slew rate is not specifiec in "bps" but rather in
> something like volts per second. But maybe it's best to keep
> this value driver-specific.

Right, I think the slew-rates values are capri specific.

Thanks for the review.

Regards,
Sherman