linux-kernel - Re: [PATCH v2 0/4] fujitsu

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Date:   Mon, 6 Mar 2017 18:40:30 +1030
From:   Jonathan Woithe <jwoithe@...t42.net>
To:     Micha?? K??pie?? <kernel@...pniu.pl>
Cc:     Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/4] fujitsu_init() cleanup

Hi Michael

Some quick feedback.

On Mon, Mar 06, 2017 at 03:31:04PM +1030, Jonathan Woithe wrote:
> > > I can add that immediately after loading the driver the value returned by a
> > > read of bl_power is 0.  As noted above, setting to 1 makes no difference to
> > > the backlight, neither does returning it to 0.
> > 
> > Have you tried setting bl_power to 4?  Because that is the value of
> > FB_BLANK_POWERDOWN, which is the value the patch is supposed to handle.
> 
> Oh no, I didn't try 4.  I should have.  I will try to squeeze in a test of
> this tonight (time is short but the test won't take a lot of time).

With an unpatched 4.5 kernel, writing 4 (as opposed to 1, which I stupidly
tried earlier) to bl_power caused the backlight to turn off.  Writing 0
turned it back on again.

With patches 1-4/4 applied, writing 4 to bl_power did *NOT* turn the
backlight off.

With patch 2 reverted, writing 4 to bl_power turned the backlight off. 
Writing 0 to bl_power turned it back on again.

This means that patch 2/4 seems to prevent bl_power from operating as
expected on the S7020 hardware.  Without this patch (but with all the others
in place) bl_power works.

I am unlikely to have any more time to investigate this further tonight. 

In light of the above findings, what would you like to do?

Regards
  jonathan