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Subject: Re: [PATCH v1 2/3] drm/tegra: plane: Correct legacy blending
To:     Thierry Reding <thierry.reding@gmail.com>
Cc:     dri-devel@lists.freedesktop.org, linux-tegra@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <8d9c7220b1d2cf126bd2030e5d232ec06f761440.1521075485.git.digetx@gmail.com>
 <00cf4565238be471c90e5823e53e0ed504869bfe.1521075485.git.digetx@gmail.com>
 <20180315102905.GB15393@ulmo>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <16e06ec0-af24-e2c1-b400-2ff1acae931c@gmail.com>
Date:   Thu, 15 Mar 2018 15:42:17 +0300
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On 15.03.2018 13:29, Thierry Reding wrote:
> On Thu, Mar 15, 2018 at 04:00:24AM +0300, Dmitry Osipenko wrote:
>> Keep old 'dependent' state of unaffected planes, this way new state takes
>> into account current state of unaffected planes.
>>
>> Fixes: ebae8d07435a ("drm/tegra: dc: Implement legacy blending")
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>>  drivers/gpu/drm/tegra/plane.c | 15 ++++++---------
>>  1 file changed, 6 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/tegra/plane.c b/drivers/gpu/drm/tegra/plane.c
>> index fc37dcf8c458..3c0cb6a04c66 100644
>> --- a/drivers/gpu/drm/tegra/plane.c
>> +++ b/drivers/gpu/drm/tegra/plane.c
>> @@ -287,13 +287,11 @@ unsigned int tegra_plane_format_adjust(unsigned int opaque)
>>  	return opaque;
>>  }
>>  
>> -unsigned int tegra_plane_get_overlap_index(struct tegra_plane *plane,
>> -					   struct tegra_plane *other)
>> +static unsigned int tegra_plane_get_overlap_index(struct tegra_plane *plane,
>> +						  struct tegra_plane *other)
> 
> I'd prefer this to be a separate patch to keep the diff down to make
> this easier to apply to v4.16. I can do that when I apply, no need to
> resend.

Okay. But now I'm thinking that it's probably not really worth to backport this
patch at all because it doesn't fix blending entirely, but only makes it good
enough to show cursor plane properly. I'll send V2.

>>  {
>>  	unsigned int index = 0, i;
>>  
>> -	WARN_ON(plane == other);
>> -
> 
> Why would this need to go away? We still shouldn't be called with plane
> == other because that makes no sense.
This can't ever happen because we are skipping 'plane' in for_each_plane_in_state().