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    Subject[PATCH 5.17 0147/1126] video: fbdev: atari: Atari 2 bpp (STe) palette bugfix
    Date
    From: Michael Schmitz <schmitzmic@gmail.com>

    commit c8be5edbd36ceed2ff3d6b8f8e40643c3f396ea3 upstream.

    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_v3aumnYW7UNUO6qMdhgfyWTyVSsCkQ@mail.gmail.com
    Tested-by: Michael Schmitz <schmitzmic@gmail.com>
    Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
    Signed-off-by: Michael Schmitz <schmitzmic@gmail.com>
    Signed-off-by: Helge Deller <deller@gmx.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/video/fbdev/atafb.c | 12 ++++++------
    1 file changed, 6 insertions(+), 6 deletions(-)

    --- a/drivers/video/fbdev/atafb.c
    +++ b/drivers/video/fbdev/atafb.c
    @@ -1683,9 +1683,9 @@ static int falcon_setcolreg(unsigned int
    ((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
    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) |

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