linux-kernel - Re: [PATCH] drm/panel: lvds: Handle the optional regulator case properly

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Date:   Thu, 11 Jan 2018 23:30:59 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Jani Nikula <jani.nikula@...ux.intel.com>
Cc:     Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Sean Paul <seanpaul@...omium.org>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Mark Brown <broonie@...nel.org>
Subject: Re: [PATCH] drm/panel: lvds: Handle the optional regulator case properly

Hi Jani,

On Thursday, 11 January 2018 16:31:59 EET Jani Nikula wrote:
> On Thu, 11 Jan 2018, Laurent Pinchart wrote:
> > My preference, however, would be for devm_regulator_get_optional() to
> > return NULL when no regulator is present. The current implementation
> > returns -ENODEV in multiple cases, making it impossible to properly
> > discriminate between having no regulator and not being able to get the
> > regulator due to an error.
> 
> Just a word of warning, IS_ERR(NULL) is false, and your proposed change
> would apparently require quite a churn all over the kernel.

That's correct, but I still think that would make the API clearer. I don't 
want to block this patch until we make such a change, but it's a good 
opportunity to discuss it. I'd like to know what Mark's opinion is.

-- 
Regards,

Laurent Pinchart