Re: [PATCH v3 2/4] pwm: rockchip: Allow polarity invert on rk3288

From: Thierry Reding
Date: Thu Aug 21 2014 - 02:40:36 EST


On Wed, Aug 20, 2014 at 02:29:17PM -0500, Dmitry Torokhov wrote:
> On August 20, 2014 1:54:11 PM CDT, Doug Anderson <dianders@xxxxxxxxxxxx> wrote:
> >On Wed, Aug 20, 2014 at 3:04 AM, Thierry Reding
> ><thierry.reding@xxxxxxxxx> wrote:
> >> On Tue, Aug 19, 2014 at 09:07:54AM -0700, Doug Anderson wrote:
> >>> The rk3288 has the ability to invert
> >>> + struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
> >>> +
> >>> + if (!pc->data->has_invert)
> >>> + return -ENOSYS;
> >>> +
>
> At the kernel summit hpa also mentioned that ENOSYS should only be
> used for missing syscalls. Not sure what error code would suit better
> here though...

I'd be interested in the rationale why ENOSYS shouldn't be used within
the kernel. As long as it doesn't leak to userspace where it could
possibly confuse applications I don't see any harm in using it.

Thierry

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