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Subject: Re: [PATCH 2/6] backlight/generic-bl: remove DRIVER1 state
To:     DRI Development <dri-devel@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Lee Jones <lee.jones@linaro.org>,
        Jingoo Han <jingoohan1@gmail.com>,
        Daniel Vetter <daniel.vetter@intel.com>
References: <20180117140159.27611-1-daniel.vetter@ffwll.ch>
 <20180117140159.27611-2-daniel.vetter@ffwll.ch>
 <9cbcb5d4-1e7c-5df6-a73c-f93b1d2fdbee@linaro.org>
 <20180117171340.GZ2759@phenom.ffwll.local>
From:   Daniel Thompson <daniel.thompson@linaro.org>
Message-ID: <519f2463-95ae-0565-9aaf-8de9c779fd7c@linaro.org>
Date:   Thu, 18 Jan 2018 09:20:32 +0000
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On 17/01/18 17:13, Daniel Vetter wrote:
> On Wed, Jan 17, 2018 at 04:44:00PM +0000, Daniel Thompson wrote:
>> On 17/01/18 14:01, Daniel Vetter wrote:
>>> Nothing in the entire tree ever sets this, which means this is dead
>>> code. Remove it.
>>>
>>> Cc: Lee Jones <lee.jones@linaro.org>
>>> Cc: Daniel Thompson <daniel.thompson@linaro.org>
>>> Cc: Jingoo Han <jingoohan1@gmail.com>
>>> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
>>
>> Not sure whether to ack this one or not.
>>
>> There is nothing wrong with the change but having taken a closer look the
>> driver seems like it exists mostly to allow mach-XXX code to plug in
>> function pointers and we don't do that sort of thing any more.
>>
>> I think the entire driver is dead code!
> 
> Well I can also supply a patch to outright nuke the code, but figuring out
> whether that's the right thing to do is definitely way above may pay grade
> :-)

I don't believe that for a second. ;-)

However after a bit more thought I think its best to take this patch as 
is and we can remove generic-bl after. Whilst I'm confident this code is 
not used, nuking it after your cleanups would result in a simpler revert 
if I were wrong.

So...

Acked-by: Daniel Thompson <daniel.thompson@linaro.org>


> I only really stitched these together after a long discussion with Meghana
> about why backlight seems to have 3+ different ways to enable/disable a
> backlight. Just trying to help a bit with getting the
> backlight_enable/disable stuff going, so that long-term, at least for
> newer drivers, we have one blessed way to do that.
> 
> btw that kind of display pm simplification matches what we've done when
> implementing atomic modesetting about 3 years ago: We've smashed all the
> various power states drm (and fbdev/fbcon) knew about into a simple "is it
> on?" boolean. Todays digital hw doesn't really know anything in-between.
> Ofc there's tons of components to switch on/off to get the entire display
> pipe up, and they might want different autosuspend delays to optimize the
> overall system, but that's orthogonal (well, driver internal
> implementation detail) really.
> 
> Cheers, Daniel
> 
>>
>>
>> Daniel.
>>
>>
>>> --- drivers/video/backlight/generic_bl.c | 5 ----- 1 file changed, 5
>>> deletions(-)
>>>
>>> diff --git a/drivers/video/backlight/generic_bl.c
>>> b/drivers/video/backlight/generic_bl.c index
>>> 67dfb939a514..4dea91acea13 100644 ---
>>> a/drivers/video/backlight/generic_bl.c +++
>>> b/drivers/video/backlight/generic_bl.c @@ -21,9 +21,6 @@ static int
>>> genericbl_intensity; static struct backlight_device
>>> *generic_backlight_device; static struct generic_bl_info *bl_machinfo;
>>> -/* Flag to signal when the battery is low */ -#define
>>> GENERICBL_BATTLOW       BL_CORE_DRIVER1 - static int
>>> genericbl_send_intensity(struct backlight_device *bd) { int intensity
>>> = bd->props.brightness; @@ -34,8 +31,6 @@ static int
>>> genericbl_send_intensity(struct backlight_device *bd) intensity = 0;
>>> if (bd->props.state & BL_CORE_SUSPENDED) intensity = 0; -	if
>>> (bd->props.state & GENERICBL_BATTLOW) -		intensity &=
>>> bl_machinfo->limit_mask; bl_machinfo->set_bl_intensity(intensity);
>>>
>