Re: "nv" driver: Option "FPDither" default value
On Tue, 2005-10-04 at 14:38 -0700, Mark Vojkovich wrote: >Whoops, I'm wrong. It turns out it's not in the EDID. For > desktop systems this is set in the control panel. For laptops, > the driver keeps a list of known panels. The iMac is essentially > a laptop. Well, it actually _could_ be in the EDID provided I could find a single panel that actually implemented the Display Information EDID Extension block as defined by VESA :) But so far, I haven't seen any. It _looks_ like the firmware is enabling it on this machine. I've modified nvidiafb to conserve the firmware setting by default, I'll send a patch doing the same to XFree if you are ok with it. Ben. ___ Devel mailing list Devel@XFree86.Org http://XFree86.Org/mailman/listinfo/devel
Re: "nv" driver: Option "FPDither" default value
Whoops, I'm wrong. It turns out it's not in the EDID. For
desktop systems this is set in the control panel. For laptops,
the driver keeps a list of known panels. The iMac is essentially
a laptop.
Mark.
On Tue, 4 Oct 2005, Benjamin Herrenschmidt wrote:
> >The iMac looks very "laptop-like" so I'm not surprised it has a
> > 6 bit panel. It might be in the EDID. I'm not sure how else
> > software would be able to know.
>
> I'll try to find somebody with access to the appropriate VESA specs to
> find out then. The "other" way to know is what Apple does in OS X for
> things like default panel gamma table, backlight value range, etc...
> they have a long table of pretty much every monitor they ever
> shipped with those informations.
>
> Another possibility, if possible (I have to dbl check the driver) would
> be to check the dither setting set by the BIOS/firmware. I'm not sure
> it's set wrong on the iMac, I suspect not, in fact, It's probably just
> nvidiafb and X "nv" that disabling it by default. Maybe if we could
> "read" it's previous state the same way we read the panel size from the
> registers, we could use that as a default value when no option is
> specified in the config file.
>
> In a similar vein, I noticed that the kernel fbdev now have some code to
> calculate timings using the CVT algorithm, and that it actually produces
> a working modeline for this panel based solely on the panel size read
> from registers, while X{Free,.org} just picks a scaled mode as 1440x900
> isn't in it's built-in list. I suppose it would be time to rework
> xf86Modes.c a bit to better deal with flat panels anyway, I'll look into
> it if I ever find time...
>
> Ben.
>
>
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Re: "nv" driver: Option "FPDither" default value
>The iMac looks very "laptop-like" so I'm not surprised it has a
> 6 bit panel. It might be in the EDID. I'm not sure how else
> software would be able to know.
I'll try to find somebody with access to the appropriate VESA specs to
find out then. The "other" way to know is what Apple does in OS X for
things like default panel gamma table, backlight value range, etc...
they have a long table of pretty much every monitor they ever
shipped with those informations.
Another possibility, if possible (I have to dbl check the driver) would
be to check the dither setting set by the BIOS/firmware. I'm not sure
it's set wrong on the iMac, I suspect not, in fact, It's probably just
nvidiafb and X "nv" that disabling it by default. Maybe if we could
"read" it's previous state the same way we read the panel size from the
registers, we could use that as a default value when no option is
specified in the config file.
In a similar vein, I noticed that the kernel fbdev now have some code to
calculate timings using the CVT algorithm, and that it actually produces
a working modeline for this panel based solely on the panel size read
from registers, while X{Free,.org} just picks a scaled mode as 1440x900
isn't in it's built-in list. I suppose it would be time to rework
xf86Modes.c a bit to better deal with flat panels anyway, I'll look into
it if I ever find time...
Ben.
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Re: "nv" driver: Option "FPDither" default value
On Mon, 3 Oct 2005, Benjamin Herrenschmidt wrote: > On Sun, 2005-10-02 at 18:32 -0700, Mark Vojkovich wrote: > >FPDither takes 8 bit output and dithers down to 6 bit. It > > will improve the quality on 6 bit panels and degrade it on 8 > > bit panels. Nearly all desktop panels are 8 bit (only very cheap > > or very old ones are not). Most laptop panels have been 6 > > bit, but some high-end laptops have 8 bit panels. > > Ok, thanks. Is there a way to "detect" the panel component size (via > EDID maybe) ? I'm actually surprised that the iMac G5 panel is only 6 > bits but heh, I suppose Apple had to cut costs on this one... I don't > suppose it could be a chip misconfiguration in the firmware causing it > to emit 6 bits data only, could it ? > The iMac looks very "laptop-like" so I'm not surprised it has a 6 bit panel. It might be in the EDID. I'm not sure how else software would be able to know. Mark. ___ Devel mailing list Devel@XFree86.Org http://XFree86.Org/mailman/listinfo/devel
Re: "nv" driver: Option "FPDither" default value
On Sun, 2005-10-02 at 18:32 -0700, Mark Vojkovich wrote: >FPDither takes 8 bit output and dithers down to 6 bit. It > will improve the quality on 6 bit panels and degrade it on 8 > bit panels. Nearly all desktop panels are 8 bit (only very cheap > or very old ones are not). Most laptop panels have been 6 > bit, but some high-end laptops have 8 bit panels. Ok, thanks. Is there a way to "detect" the panel component size (via EDID maybe) ? I'm actually surprised that the iMac G5 panel is only 6 bits but heh, I suppose Apple had to cut costs on this one... I don't suppose it could be a chip misconfiguration in the firmware causing it to emit 6 bits data only, could it ? Thanks, Ben. ___ Devel mailing list Devel@XFree86.Org http://XFree86.Org/mailman/listinfo/devel
Re: "nv" driver: Option "FPDither" default value
FPDither takes 8 bit output and dithers down to 6 bit. It will improve the quality on 6 bit panels and degrade it on 8 bit panels. Nearly all desktop panels are 8 bit (only very cheap or very old ones are not). Most laptop panels have been 6 bit, but some high-end laptops have 8 bit panels. Mark. On Sun, 2 Oct 2005, Benjamin Herrenschmidt wrote: > Hi Mark ! > > I have a small question about the "nv" driver... > > What is the reason why option "FPDither" is not enabled by default ? > > It definitely makes a huge difference in quality on the iMac G5 I have > here. Can it actually reduce the quality on other setups or impact > performances ? > > Regards, > Ben. > > > ___ Devel mailing list Devel@XFree86.Org http://XFree86.Org/mailman/listinfo/devel
"nv" driver: Option "FPDither" default value
Hi Mark ! I have a small question about the "nv" driver... What is the reason why option "FPDither" is not enabled by default ? It definitely makes a huge difference in quality on the iMac G5 I have here. Can it actually reduce the quality on other setups or impact performances ? Regards, Ben. ___ Devel mailing list Devel@XFree86.Org http://XFree86.Org/mailman/listinfo/devel
