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    Subject[PATCH 4.9 30/53] fbdev: sm712fb: fix brightness control on reboot, dont set SR30
    Date
    From: Yifeng Li <tomli@tomli.me>

    commit 5481115e25e42b9215f2619452aa99c95f08492f upstream.

    On a Thinkpad s30 (Pentium III / i440MX, Lynx3DM), rebooting with
    sm712fb framebuffer driver would cause the role of brightness up/down
    button to swap.

    Experiments showed the FPR30 register caused this behavior. Moreover,
    even if this register don't have side-effect on other systems, over-
    writing it is also highly questionable, since it was originally
    configurated by the motherboard manufacturer by hardwiring pull-down
    resistors to indicate the type of LCD panel. We should not mess with
    it.

    Stop writing to the SR30 (a.k.a FPR30) register.

    Signed-off-by: Yifeng Li <tomli@tomli.me>
    Tested-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
    Cc: Teddy Wang <teddy.wang@siliconmotion.com>
    Cc: <stable@vger.kernel.org> # v4.4+
    Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/video/fbdev/sm712fb.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    --- a/drivers/video/fbdev/sm712fb.c
    +++ b/drivers/video/fbdev/sm712fb.c
    @@ -1144,8 +1144,8 @@ static void sm7xx_set_timing(struct smtc

    /* init SEQ register SR30 - SR75 */
    for (i = 0; i < SIZE_SR30_SR75; i++)
    - if ((i + 0x30) != 0x62 && (i + 0x30) != 0x6a &&
    - (i + 0x30) != 0x6b)
    + if ((i + 0x30) != 0x30 && (i + 0x30) != 0x62 &&
    + (i + 0x30) != 0x6a && (i + 0x30) != 0x6b)
    smtc_seqw(i + 0x30,
    vgamode[j].init_sr30_sr75[i]);


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