lkml.org 
[lkml]   [2020]   [Oct]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.9 040/139] video: fbdev: vga16fb: fix setting of pixclock because a pass-by-value error
    Date
    From: Colin Ian King <colin.king@canonical.com>

    [ Upstream commit c72fab81ceaa54408b827a2f0486d9a0f4be34cf ]

    The pixclock is being set locally because it is being passed as a
    pass-by-value argument rather than pass-by-reference, so the computed
    pixclock is never being set in var->pixclock. Fix this by passing
    by reference.

    [This dates back to 2002, I found the offending commit from the git
    history git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git ]

    Addresses-Coverity: ("Unused value")
    Signed-off-by: Colin Ian King <colin.king@canonical.com>
    Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
    Cc: Jani Nikula <jani.nikula@intel.com>
    [b.zolnierkie: minor patch summary fixup]
    [b.zolnierkie: removed "Fixes:" tag (not in upstream tree)]
    Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
    Link: https://patchwork.freedesktop.org/patch/msgid/20200723170227.996229-1-colin.king@canonical.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/video/fbdev/vga16fb.c | 14 +++++++-------
    1 file changed, 7 insertions(+), 7 deletions(-)

    diff --git a/drivers/video/fbdev/vga16fb.c b/drivers/video/fbdev/vga16fb.c
    index ee6957a799bb6..aea8fd85cbf70 100644
    --- a/drivers/video/fbdev/vga16fb.c
    +++ b/drivers/video/fbdev/vga16fb.c
    @@ -243,7 +243,7 @@ static void vga16fb_update_fix(struct fb_info *info)
    }

    static void vga16fb_clock_chip(struct vga16fb_par *par,
    - unsigned int pixclock,
    + unsigned int *pixclock,
    const struct fb_info *info,
    int mul, int div)
    {
    @@ -259,14 +259,14 @@ static void vga16fb_clock_chip(struct vga16fb_par *par,
    { 0 /* bad */, 0x00, 0x00}};
    int err;

    - pixclock = (pixclock * mul) / div;
    + *pixclock = (*pixclock * mul) / div;
    best = vgaclocks;
    - err = pixclock - best->pixclock;
    + err = *pixclock - best->pixclock;
    if (err < 0) err = -err;
    for (ptr = vgaclocks + 1; ptr->pixclock; ptr++) {
    int tmp;

    - tmp = pixclock - ptr->pixclock;
    + tmp = *pixclock - ptr->pixclock;
    if (tmp < 0) tmp = -tmp;
    if (tmp < err) {
    err = tmp;
    @@ -275,7 +275,7 @@ static void vga16fb_clock_chip(struct vga16fb_par *par,
    }
    par->misc |= best->misc;
    par->clkdiv = best->seq_clock_mode;
    - pixclock = (best->pixclock * div) / mul;
    + *pixclock = (best->pixclock * div) / mul;
    }

    #define FAIL(X) return -EINVAL
    @@ -497,10 +497,10 @@ static int vga16fb_check_var(struct fb_var_screeninfo *var,

    if (mode & MODE_8BPP)
    /* pixel clock == vga clock / 2 */
    - vga16fb_clock_chip(par, var->pixclock, info, 1, 2);
    + vga16fb_clock_chip(par, &var->pixclock, info, 1, 2);
    else
    /* pixel clock == vga clock */
    - vga16fb_clock_chip(par, var->pixclock, info, 1, 1);
    + vga16fb_clock_chip(par, &var->pixclock, info, 1, 1);

    var->red.offset = var->green.offset = var->blue.offset =
    var->transp.offset = 0;
    --
    2.25.1


    \
     
     \ /
      Last update: 2020-10-27 15:07    [W:4.321 / U:0.544 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site