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Date:	Wed, 15 Apr 2015 16:52:26 -0700
From:	Andy Lutomirski <>
To:	Andy Walls <>
Cc:	"Luis R. Rodriguez" <>,,
	Toshi Kani <>,
	"H. Peter Anvin" <>, Ingo Molnar <>,
	"" <>,
	Hal Rosenstock <>,
	Sean Hefty <>,
	Suresh Siddha <>,
	Rickard Strandqvist <>,
	Mike Marciniszyn <>,
	Roland Dreier <>,
	Juergen Gross <>,
	Mauro Carvalho Chehab <>,
	Borislav Petkov <>, Mel Gorman <>,
	Vlastimil Babka <>,
	Davidlohr Bueso <>,
	Dave Hansen <>,
	Jean-Christophe Plagniol-Villard <>,
	Thomas Gleixner <>,
	Ville Syrjälä <>,
	Linux Fbdev development list <>,, X86 ML <>
Subject: Re: ioremap_uc() followed by set_memory_wc() - burrying MTRR

On Wed, Apr 15, 2015 at 3:50 PM, Andy Walls <> wrote:
> On Wed, 2015-04-15 at 13:42 -0700, Andy Lutomirski wrote:
>> On Mon, Apr 13, 2015 at 10:49 AM, Luis R. Rodriguez <> wrote:
>> > c) ivtv: the driver does not have the PCI space mapped out separately, and
>> > in fact it actually does not do the math for the framebuffer, instead it lets
>> > the device's own CPU do that and assume where its at, see
>> > ivtvfb_get_framebuffer() and CX2341X_OSD_GET_FRAMEBUFFER, it has a get
>> > but not a setter. Its not clear if the firmware would make a split easy.
>> > We'd need ioremap_ucminus() here too and __arch_phys_wc_add().
>> >
>> IMO this should be conceptually easy to split.  Once we get the
>> framebuffer address, just unmap it (or don't prematurely map it) and
>> then ioremap the thing.
> Not so easy.  The main ivtv driver has already set up the PCI device and
> done the mapping for the MPEG-2 decoder/video output engine.  The video
> decoder/output device nodes might already be open by user space calling
> into the main driver, before the ivtvfb module is even loaded.

Surely the MPEG-2 decoder/video engine won't overlap the framebuffer,
though.  Am I missing something?


> This could be mitigated by integrating all the ivtvfb module code into
> the main ivtv module.  But even then not every PVR-350 owner wants to
> use the video output OSD as a framebuffer.  Users might just want an
> actual OSD overlaying their TV video playback.
> Regards,
> Andy

Andy Lutomirski
AMA Capital Management, LLC
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