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From:   Benjamin Gaignard <benjamin.gaignard@linaro.org>
Date:   Wed, 24 Apr 2019 14:26:36 +0200
Message-ID: <CA+M3ks4wYvutkSbYu_xo=xwvr=ObqMPS7Zv0oaLL3MZzBbRBFw@mail.gmail.com>
Subject: Re: [PATCH] drm/stm: ltdc: fix data enable polarity
To:     Philippe CORNU <philippe.cornu@st.com>
Cc:     Mukesh Ojha <mojha@codeaurora.org>,
        Yannick FERTRE <yannick.fertre@st.com>,
        Vincent ABRIOU <vincent.abriou@st.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre TORGUE <alexandre.torgue@st.com>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        "linux-stm32@st-md-mailman.stormreply.com" 
        <linux-stm32@st-md-mailman.stormreply.com>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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Le lun. 1 avr. 2019 =C3=A0 11:18, Philippe CORNU <philippe.cornu@st.com> a =
=C3=A9crit :
>
>
>
> On 3/29/19 10:32 PM, Mukesh Ojha wrote:
> >
> > On 3/29/2019 9:20 PM, Yannick Fertr=C3=A9 wrote:
> >> Wrong DISPLAY_FLAGS used to set the data enable polarity.
> > Used or checked?
> > Can you also explain how it is wrong to check against this FLAG in comm=
it?
>
> Dear Yannick,
> Many thanks for your patch,
>
> Dear Mukesh,
> Many thanks for your comment,
>
> Looking deeper in the stm32 LTDC Ref man chapter, we can read:
>
> Bit 30 VSPOL: vertical synchronization polarity
> This bit is set and cleared by software.
> 0: vertical synchronization is active low.
> 1: vertical synchronization is active high.
>
> Bit 29 DEPOL: not data enable polarity
> This bit is set and cleared by software.
> 0: not data enable polarity is active low.
> 1: not data enable polarity is active high.
>
> So I suggest the following commit message:
> "According to the STM32 LTDC documentation, GCR_DEPOL bit need to be set
> with DISPLAY_FLAGS_DE_LOW but not with DISPLAY_FLAGS_DE_HIGH."
>
> With that or something similar
>
> Acked-by: Philippe Cornu <philippe.cornu@st.com>
>

Applied on drm-misc-next,
Thanks,
Benjamin

> Philippe :-)
>
>
> >>
> >> Signed-off-by: Yannick Fertr=C3=A9 <yannick.fertre@st.com>
> >> ---
> >>    drivers/gpu/drm/stm/ltdc.c | 2 +-
> >>    1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
> >> index b1741a9..6ba326a 100644
> >> --- a/drivers/gpu/drm/stm/ltdc.c
> >> +++ b/drivers/gpu/drm/stm/ltdc.c
> >> @@ -555,7 +555,7 @@ static void ltdc_crtc_mode_set_nofb(struct drm_crt=
c *crtc)
> >>      if (vm.flags & DISPLAY_FLAGS_VSYNC_HIGH)
> >>              val |=3D GCR_VSPOL;
> >>
> >> -    if (vm.flags & DISPLAY_FLAGS_DE_HIGH)
> >> +    if (vm.flags & DISPLAY_FLAGS_DE_LOW)
> >>              val |=3D GCR_DEPOL;
> >>
> >>      if (vm.flags & DISPLAY_FLAGS_PIXDATA_NEGEDGE)
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