Re: [PATCH 1/2] Revert "drm: Add and handle new aspect ratios in DRM layer"

From: Daniel Vetter <daniel.vetter@ffwll.ch>
To: Alex Deucher <alexdeucher@gmail.com>
Cc: Jose Abreu <Jose.Abreu@synopsys.com>, Jia <lin.a.jia@intel.com>,
	Akashdeep Sharma <akashdeep.sharma@intel.com>,
	Emil Velikov <emil.l.velikov@gmail.com>,
	Maling list - DRI developers <dri-devel@lists.freedesktop.org>,
	Jim Bride <jim.bride@linux.intel.com>,
	Lin@freedesktop.org
Subject: Re: [PATCH 1/2] Revert "drm: Add and handle new aspect ratios in DRM layer"
Date: Fri, 11 Nov 2016 18:08:44 +0100	[thread overview]
Message-ID: <CAKMK7uEKBNfUXAEgO0w6Wa0osR-1ktff4Z5L6naOKkSp5+i11Q@mail.gmail.com> (raw)
In-Reply-To: <CADnq5_NrNBsZrotjeGiDcsAOz9zHuMyMPebp-AOM43ajWhf0UQ@mail.gmail.com>

On Fri, Nov 11, 2016 at 6:07 PM, Alex Deucher <alexdeucher@gmail.com> wrote:
>> This was with sna, which does this:
>>  #define KNOWN_MODE_FLAGS ((1<<14)-1)
>>  if (mode->status == MODE_OK && kmode->flags & ~KNOWN_MODE_FLAGS)
>>         mode->status = MODE_BAD; /* unknown flags => unhandled */
>> so all the modes with an aspect ratio just vanished.
>>
>> -modesetting and -ati on the other hand just copy over the unknown
>> bits into the xrandr mode structure, which sounds dubious at best:
>>  mode->Flags = kmode->flags; //& FLAG_BITS;
>> I've not checked what damage it can actually cause.
>
> What problems could this cause?  Presumably the kernel driver has
> validated the modes already or they wouldn't showing up in the first
> place.  Or is your concern that something in the xserver itself may
> barf on the new flags?

See above snipped from sna, we now lost a bunch of modes.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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