Re: [PATCH] vgacon: Workaround for resize bug in some chipsets

["Jason Dravet" <dravet@hotmail.com>]

> From: Samuel Thibault <samuel.thibault@ens-lyon.org>
> To: Jason Dravet <dravet@hotmail.com>
> CC: 7eggert@gmx.de, adaplas@gmail.com, torvalds@osdl.org, 
> akpm@osdl.org,davej@redhat.com, linux-kernel@vger.kernel.org
> Subject: Re: [PATCH] vgacon: Workaround for resize bug in some chipsets
> Date: Wed, 16 Nov 2005 03:25:08 +0100
>
> Hi,
>
> Jason Dravet, le Tue 15 Nov 2005 19:50:39 -0600, a écrit :
> > Here are the results:
> > y=25   fonth=16   deffh=16   vidfh=16   scanl=400
> > overflow=ff
> > vsync_end=8f
> > vdisp_end=1f
>
> Ah, this is odd indeed: your hardware uses 800 scanlines
> (overflow:(512+256)+vdisp_end:0x1f), while the actual needed lines
> should be y:25*fonth:16 ... Maybe it is actually using a 32 lines font.
>
> Just to make sure about every VGA bits, could you install the
> svgatextmode package, which holds a getVGAreg command, and run twice
>
> for i in `seq 0 24` ; do getVGAreg CRTC $i ; done
>
> The first time while having a correct full text screen rendering, and
> the second time after vgacon_doresize() has blanked the bottom half of
> the screen.
>
> Regards,
> Samuel

For some reason my custom 2.6.14 kernels no longer boot.  While I look into 
this here are the results when only half the screen works:

VGA 'CRTC' register, index 0 (=0x0) contains 89 (=0x59 =b01011001)
VGA 'CRTC' register, index 1 (=0x1) contains 79 (=0x4f =b01001111)
VGA 'CRTC' register, index 2 (=0x2) contains 79 (=0x4f =b01001111)
VGA 'CRTC' register, index 3 (=0x3) contains 157 (=0x9d =b10011101)
VGA 'CRTC' register, index 4 (=0x4) contains 84 (=0x54 =b01010100)
VGA 'CRTC' register, index 5 (=0x5) contains 27 (=0x1b =b00011011)
VGA 'CRTC' register, index 6 (=0x6) contains 255 (=0xff =b11111111)
VGA 'CRTC' register, index 7 (=0x7) contains 191 (=0xbf =b10111111)
VGA 'CRTC' register, index 8 (=0x8) contains 0 (=0x00 =b00000000)
VGA 'CRTC' register, index 9 (=0x9) contains 239 (=0xef =b11101111)
VGA 'CRTC' register, index 10 (=0xa) contains 13 (=0x0d =b00001101)
VGA 'CRTC' register, index 11 (=0xb) contains 14 (=0x0e =b00001110)
VGA 'CRTC' register, index 12 (=0xc) contains 40 (=0x28 =b00101000)
VGA 'CRTC' register, index 13 (=0xd) contains 240 (=0xf0 =b11110000)
VGA 'CRTC' register, index 14 (=0xe) contains 42 (=0x2a =b00101010)
VGA 'CRTC' register, index 15 (=0xf) contains 32 (=0x20 =b00100000)
VGA 'CRTC' register, index 16 (=0x10) contains 125 (=0x7d =b01111101)
VGA 'CRTC' register, index 17 (=0x11) contains 143 (=0x8f =b10001111)
VGA 'CRTC' register, index 18 (=0x12) contains 143 (=0x8f =b10001111)
VGA 'CRTC' register, index 19 (=0x13) contains 40 (=0x28 =b00101000)
VGA 'CRTC' register, index 20 (=0x14) contains 31 (=0x1f =b00011111)
VGA 'CRTC' register, index 21 (=0x15) contains 30 (=0x1e =b00011110)
VGA 'CRTC' register, index 22 (=0x16) contains 0 (=0x00 =b00000000)
VGA 'CRTC' register, index 23 (=0x17) contains 163 (=0xa3 =b10100011)
VGA 'CRTC' register, index 24 (=0x18) contains 255 (=0xff =b11111111)

I will send the whole screen results when I find and fix the problem.  I am 
running the fedora core development system with all but todays updates.

Thanks,
Jason


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