[Xorg-driver-geode] display mode with 800x480 on geode-2.11.1
wan michael
michalwan at gmail.com
Wed Apr 29 09:58:26 PDT 2009
at first, thanks for your best and detail replies. next, I have other issues
to ask for you.
my device uses geode lx processor (500MHZ) with 7" LCD display. at present,
I'm porting google android to my device. compile kernel 2.6.27 with geode lx
frame buffer,
not the vesa framebuffer, one of the question found is that after
android booting, the display is blinking. it can obviously see the highlight
horizontal line,
in the beginning, i think it maybe is related to vsync, but no matter
whatever i adjust it to, it's no use. at the same
time, compile kernel with intelfb, then run android on PC with intel
processor, the display
is very well. of course, the PC's intel processor (2.6G) is much faster than
geode processor.
but it should not be the just reason, because android can run well on lower
frequency smartphone.
since andoid uses openGL ES that i am not familiar with too much. but it
seems to be much
related to the geode framebuffer.
expect to get your professional hints or suggestion!
2009/4/29 Martin-Éric Racine <q-funk at iki.fi>
> As I recall, the only reason why some specific resolutions are in the
> source code is because they are those that TFT output can only
> support. For VGA output, the driver should be capable of extrapolating
> any arbitrary resolution that fits within its maximum clock pitch.
>
> On Tue, Apr 28, 2009 at 5:28 PM, John Yoder <john.yoder at twny.net> wrote:
> > I apologize for not getting back to you sooner. To answer your earlier
> > question about adding a resolution that is currently not available, I
> > would submit a patch, as I believe I can infer that you are using the
> > VGA port rather then a direct connect to the panel connector. It
> > simplifies things a bit.
> >
> > As I recall, the table entries are as follows:
> > <name> <refresh,> <xres> <yres> <pixclock> <left_margin>
> > <right_margin> <upper_margin> <lower_margin> < hsync_length>
> > <vsync_length> <sync> <vmode>
> > What is required are derived by calculation from modelines. So you will
> > need to get a working custom modeline to start. Then some calculations.
> > Lets start with an explanation of the fields:
> >
> > pixclock - pixel clock in pico seconds (I believe this is correct)
> > left_margin - time from sync to picture
> > right_margin - time from picture to sync
> > upper_margin - time from sync to picture
> > lower_margin - time from picture to sync
> > hsync_lenth - length of horizontal sync
> > vsync_length - length of vertical sync
> >
> > Modelines have the following fields
> >
> > Modeline <name> <DCL> <HR> <HPS> <HPE> <HFL> <VR> <VPS> <VPE> <VFL>
> >
> > Where:
> > name - name assigned to mode
> > DCL - Dot Clock (MHz)
> > HR & VR - Horizontal and Vertical resolution
> > HPS, HPE, VPS, VPE - Horizontal and Vertical Pulse Start and End
> > also known as Front and Back Porch
> > HFL & VFL - Horizontal and Vertical Field Length
> >
> > To get values that are required for these the calculations are as
> > follows:
> > left_margin = HFL - HPE
> > right_margin = HPS - HR
> > hsync_length = HFE - HPS
> >
> > upper_margin = VFL - VPE
> > lower_margin = VPS - VR
> > vsync_length = VPE - VPS
> >
> > This should get you close. This information was pulled from memory and a
> > couple different sources.
> > To get the custom modeline, I typically use
> > http://xtiming.sourceforge.net/cgi-bin/xtiming.pl to get a close
> > modeline. If this doesn't work, I check the log file to verify the DCL
> > is within the range of the LX DCL. If it is and I get a black screen, I
> > verify the other values like HFL & VFL then move around the Horizontal
> > and Vertical Sync Time in the above website. Waving a rubber chicken or
> > other Voodoo incantations may help as well. :)
> > I pulled this information from:
> > http://ftp.utcluj.ro/pub/docs/how-to/mini-how-to/Modeline
> > http://tldp.org/HOWTO/Framebuffer-HOWTO-18.html
> >
> > For further reading on the subject of how Xorg get the timings:
> > http://en.tldp.org/HOWTO/XFree86-Video-Timings-HOWTO/
> >
> > I hope this helps.
> >
> > Best Regards,
> >
> > John Yoder
> >
> > On Tue, 2009-04-28 at 10:51 +0800, wan michael wrote:
> >> in the file drivers/video/geode/lxfb_core.c
> >>
> >> static struct fb_videomode geode_modedb[] __initdata = {
> >> /* 640x480-60 */
> >> { NULL, 60, 640, 480, 39682, 48, 8, 25, 2, 88, 2,
> >> FB_SYNC_HOR_HIGH_ACT | FB_SYNC_VERT_HIGH_ACT,
> >> FB_VMODE_NONINTERLACED, 0 },
> >> ......
> >> }
> >>
> >> now i want to add the mode of 800x480, but how to calculate these
> >> values. such as
> >> 800x480-60, 800x480-70, 800x480-72, 800x480-80, 80x480-85, and so on.
> >> it is the case of changing the refresh frequency, what is the
> >> calculation?
> >>
> >>
> >> 2009/4/26 wan michael <michalwan at gmail.com>
> >> is it possible to be standard modeline like 800X600 through
> >> adding 800x480 into geode driver, not just the custom modeline
> >> in the xorg.conf ?
> >>
> >>
> >> another question, like 7" LCD display, they are commonly used
> >> in the embedded device, like MID or handheld device, the most
> >> resolution is 800x480. not like common PC, which can provide
> >> much more higher resolution than 7" LCD display, such as
> >> 1024X768, and so on. So, when used for PC, it always selects
> >> the best resolution, and it can not do that for the embedded
> >> device, for the reason of 7" LCD display supporting the most
> >> high resolution is 800X480, if both of them can not match
> >> well, the display will not be normal. so is there one way to
> >> automatically match them, adapting to 800X480, not the higher?
> >>
> >>
> >> 2009/4/24 John Yoder <jtyoder at twny.net>
> >>
> >> On Wed, 2009-04-22 at 14:20 +0800, wan michael wrote:
> >>
> >>
> >> > hi
> >> >
> >> > can the geode driver provide the mode 800x480? if
> >> > so, it can meet the 7' LCD display which is 800x480,
> >> > and not the standard modes on pc.
> >> >
> >> >
> >> > _______________________________________________
> >> > Xorg-driver-geode mailing list
> >> > Xorg-driver-geode at lists.x.org
> >> > http://lists.x.org/mailman/listinfo/xorg-driver-geode
> >> It should be able to provide the 800x480 mode.
> >> However, that will require a custom modeline in the
> >> xorg.cong. I would use one of the modeline calculators
> >> as a starting point. Whenever I need to provide custom
> >> modelines it takes a bit to get the dot clock
> >> frequency of the LX and Monitor to be correct, but not
> >> typically much of a problem.
> >>
> >> Best Regards,
> >>
> >> John Yoder
> >>
> >>
> >
> >
> > _______________________________________________
> > Xorg-driver-geode mailing list
> > Xorg-driver-geode at lists.x.org
> > http://lists.x.org/mailman/listinfo/xorg-driver-geode
> >
>
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