The code to set the shifter STe palette registers has a long standing operator precedence bug, manifesting as colors set on a 2 bits per pixel frame buffer coming up with a distinctive blue tint.
Add parentheses around the calculation of the per-color palette data before shifting those into their respective bit field position.
This bug goes back a long way (2.4 days at the very least) so there won't be a Fixes: tag.
Tested on ARAnyM as well on Falcon030 hardware.
Cc: stable@vger.kernel.org Reported-by: Geert Uytterhoeven geert@linux-m68k.org Link: https://lore.kernel.org/all/CAMuHMdU3ievhXxKR_xi_v3aumnYW7UNUO6qMdhgfyWTyVSs... Tested-by: Michael Schmitz schmitzmic@gmail.com Signed-off-by: Michael Schmitz schmitzmic@gmail.com --- drivers/video/fbdev/atafb.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/video/fbdev/atafb.c b/drivers/video/fbdev/atafb.c index e3812a8ff55a..29e650ecfceb 100644 --- a/drivers/video/fbdev/atafb.c +++ b/drivers/video/fbdev/atafb.c @@ -1683,9 +1683,9 @@ static int falcon_setcolreg(unsigned int regno, unsigned int red, ((blue & 0xfc00) >> 8)); if (regno < 16) { shifter_tt.color_reg[regno] = - (((red & 0xe000) >> 13) | ((red & 0x1000) >> 12) << 8) | - (((green & 0xe000) >> 13) | ((green & 0x1000) >> 12) << 4) | - ((blue & 0xe000) >> 13) | ((blue & 0x1000) >> 12); + ((((red & 0xe000) >> 13) | ((red & 0x1000) >> 12)) << 8) | + ((((green & 0xe000) >> 13) | ((green & 0x1000) >> 12)) << 4) | + ((blue & 0xe000) >> 13) | ((blue & 0x1000) >> 12); ((u32 *)info->pseudo_palette)[regno] = ((red & 0xf800) | ((green & 0xfc00) >> 5) | ((blue & 0xf800) >> 11)); @@ -1971,9 +1971,9 @@ static int stste_setcolreg(unsigned int regno, unsigned int red, green >>= 12; if (ATARIHW_PRESENT(EXTD_SHIFTER)) shifter_tt.color_reg[regno] = - (((red & 0xe) >> 1) | ((red & 1) << 3) << 8) | - (((green & 0xe) >> 1) | ((green & 1) << 3) << 4) | - ((blue & 0xe) >> 1) | ((blue & 1) << 3); + ((((red & 0xe) >> 1) | ((red & 1) << 3)) << 8) | + ((((green & 0xe) >> 1) | ((green & 1) << 3)) << 4) | + ((blue & 0xe) >> 1) | ((blue & 1) << 3); else shifter_tt.color_reg[regno] = ((red & 0xe) << 7) |