Dear all,
I am trying to fix an issue with color inversion in the current offb.c
implementation. I am using a Mac Mini G4 (PPC) with:
[ 0.844144] fb0: Open Firmware frame buffer device on
/pci@f0000000/ATY,RockHopper2Parent@10/ATY,RockHopper2_A@0
reported as [*]. I have tried looking at the upstream code source, and
it appears that my configuration falls into the 'cmap_simple'. But
other than that I failed to understand what could be wrong (palette
would be setup backward).
What are the low level tool (user-space) I can use to try to
understand what is wrong with offb on my machine without rebuilding
the kernel (CONFIG_FB_OF is not a module) ?
Thanks much,
[*] $ fbset -i
mode "800x600-186"
# D: 100.000 MHz, H: 119.048 kHz, V: 186.012 Hz
geometry 800 600 800 600 8
timings 10000 16 16 16 16 8 8
rgba 8/0,8/0,8/0,0/0
endmode
Frame buffer device information:
Name : OFfb ATY,RockHo
Address : 0x9c008000
Size : 614400
Type : PACKED PIXELS
Visual : PSEUDOCOLOR
XPanStep : 0
YPanStep : 0
YWrapStep : 0
LineLength : 1024
Accelerator : No
Hi Mathieu,
On Thu, Jun 9, 2016 at 2:25 PM, Mathieu Malaterre [off-list ref] wrote:
I am trying to fix an issue with color inversion in the current offb.c
implementation. I am using a Mac Mini G4 (PPC) with:
[ 0.844144] fb0: Open Firmware frame buffer device on
/pci@f0000000/ATY,RockHopper2Parent@10/ATY,RockHopper2_A@0
reported as [*]. I have tried looking at the upstream code source, and
it appears that my configuration falls into the 'cmap_simple'. But
other than that I failed to understand what could be wrong (palette
would be setup backward).
The palette code for cmap_simple writes the color components in the
order RGB, while your card seems to need BGR.
Hence either the cmap_addr/cmap_data registers are wrong, or
you have to add a cmap_inverted type that writes in the BGR order.
For both cases, you have to add a check to offb_init_palette_hacks() in
drivers/video/fbdev/offb.c.
What are the low level tool (user-space) I can use to try to
understand what is wrong with offb on my machine without rebuilding
the kernel (CONFIG_FB_OF is not a module) ?
I'm afraid you can't do much from userspace.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
Geert,
On Fri, Jun 17, 2016 at 9:11 AM, Geert Uytterhoeven
[off-list ref] wrote:
Hi Mathieu,
On Thu, Jun 9, 2016 at 2:25 PM, Mathieu Malaterre [off-list ref] wrote:
quoted
I am trying to fix an issue with color inversion in the current offb.c
implementation. I am using a Mac Mini G4 (PPC) with:
[ 0.844144] fb0: Open Firmware frame buffer device on
/pci@f0000000/ATY,RockHopper2Parent@10/ATY,RockHopper2_A@0
reported as [*]. I have tried looking at the upstream code source, and
it appears that my configuration falls into the 'cmap_simple'. But
other than that I failed to understand what could be wrong (palette
would be setup backward).
The palette code for cmap_simple writes the color components in the
order RGB, while your card seems to need BGR.
Hence either the cmap_addr/cmap_data registers are wrong, or
you have to add a cmap_inverted type that writes in the BGR order.
For both cases, you have to add a check to offb_init_palette_hacks() in
drivers/video/fbdev/offb.c.
Well I tried a (very naive) patch as follow:
--- a/drivers/video/fbdev/offb.c 2016-09-13 15:33:41.043843352 +0200
+++ b/drivers/video/fbdev/offb.c 2016-08-20 18:11:18.000000000 +0200
@@ -133,9 +133,9 @@
switch (par->cmap_type) {
case cmap_simple:
writeb(regno, par->cmap_adr);
- writeb(blue, par->cmap_data);
- writeb(green, par->cmap_data);
writeb(red, par->cmap_data);
+ writeb(green, par->cmap_data);
+ writeb(blue, par->cmap_data);
break;
case cmap_M3A:
/* Clear PALETTE_ACCESS_CNTL in DAC_CNTL */
However it does not seems to fix the Red / Blue color inversion I am seeing.
Could you please be a little more verbose in the way I need to reorder
color component from RGB to BGR ?
Thanks again
-M