linux-kernel - Re: [PATCH] drm/stm: ltdc: fix data enable polarity

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Date:   Wed, 24 Apr 2019 14:26:36 +0200
From:   Benjamin Gaignard <benjamin.gaignard@...aro.org>
To:     Philippe CORNU <philippe.cornu@...com>
Cc:     Mukesh Ojha <mojha@...eaurora.org>,
        Yannick FERTRE <yannick.fertre@...com>,
        Vincent ABRIOU <vincent.abriou@...com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre TORGUE <alexandre.torgue@...com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/stm: ltdc: fix data enable polarity

Le lun. 1 avr. 2019 à 11:18, Philippe CORNU <philippe.cornu@...com> a écrit :
>
>
>
> On 3/29/19 10:32 PM, Mukesh Ojha wrote:
> >
> > On 3/29/2019 9:20 PM, Yannick Fertré 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 commit?
>
> 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@...com>
>

Applied on drm-misc-next,
Thanks,
Benjamin

> Philippe :-)
>
>
> >>
> >> Signed-off-by: Yannick Fertré <yannick.fertre@...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_crtc *crtc)
> >>      if (vm.flags & DISPLAY_FLAGS_VSYNC_HIGH)
> >>              val |= GCR_VSPOL;
> >>
> >> -    if (vm.flags & DISPLAY_FLAGS_DE_HIGH)
> >> +    if (vm.flags & DISPLAY_FLAGS_DE_LOW)
> >>              val |= GCR_DEPOL;
> >>
> >>      if (vm.flags & DISPLAY_FLAGS_PIXDATA_NEGEDGE)
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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