Re: [PATCH v2 7/7] ARM: davinci: Start using gpiolib API inplaceof inline functions

From: Sekhar Nori
Date: Thu Jun 20 2013 - 05:19:46 EST


On 6/14/2013 3:05 PM, Philip Avinash wrote:
> Remove NEED_MACH_GPIO_H config select option for ARCH_DAVINCI to start
> use gpiolib interface for davinci platforms. However with this software
> latencies for gpio_get/set APIs will affect. Latency has increased by 18
> microsecond with gpiolib API as compared with inline API's.
>
> Software latency is calculated on da850 EVM for gpio_get_value API by
> taking the printk timing for API execution with interrupts disabled.
> Experiment has done for inline and gpiolib API interface.
>
> inline gpio API with interrupt disabled
> [ 29.734337] before gpio_get
> [ 29.736847] after gpio_get
>
> Time difference 0.00251
>
> gpio library with interrupt disabled
> [ 272.876763] before gpio_get
> [ 272.879291] after gpio_get
>
> Time difference 0.002528
> Latency increased by (0.002528 - 0.00251) = 18 microsecond.
>
> Also being here
> - Moved following definitions from mach folder to include directory
> struct davinci_gpio_controller
> Macro GPIO(x)
> inline function __gpio_mask

> - Removed GPIO_TYPE_DAVINCI enum definition as GPIO Davinci is converted
> to Linux device driver model.

This is bit out-of-place here. Why not do it along with removal of its
last usage in <soc>.c files?

Rest of the patch looks good to me.

Thanks,
Sekhar
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