Re: [PATCH v1 10/12] input: keypad_matrix: use usleep_range() for scan delay

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 06/21/2013 12:09 PM, Gerhard Sittig wrote:
> querying keyboards isn't a time critical task and does not depend on
> exact timing in the microseconds order -- the timeouts and delays are
> arbitrary choices or educated guesses at best anyway

> diff --git a/Documentation/devicetree/bindings/input/gpio-matrix-keypad.txt b/Documentation/devicetree/bindings/input/gpio-matrix-keypad.txt

> @@ -93,7 +93,10 @@ Optional Properties:
>  			a column line and reading back its row status,
>  			such that pin levels can settle after
>  			propagating through the matrix and its
> -			associated hardware components
> +			associated hardware components, can be specified
> +			with either one value giving the exact delay, or
> +			with two values giving a delay range (allowing
> +			for reduced timer management overhead)
>  - col-switch-delay-ms:	columns switch interval in milliseconds instead
>  			of using interrupts to detect key press changes,
>  			enables polling mode when specified
> @@ -146,7 +149,7 @@ Examples:
>  	matrix_keypad {
>  		compatible = "gpio-matrix-keypad";
>  		debounce-delay-ms = <5>;
> -		col-scan-delay-us = <1>;
> +		col-scan-delay-us = <2 10>;

Is it really useful to change the binding this way?

The values in DT presumably represent the minimum delays that the HW
will tolerate or that are useful. SW is always free to scan more slowly
than that. As such, if you're simply modifying the driver to allow more
flexibility in timing, then I don't think you have to modify the DT
binding to allow for this?
--
To unsubscribe from this list: send the line "unsubscribe linux-input" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Media Devel]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Linux Wireless Networking]     [Linux Omap]

  Powered by Linux