From: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
To: Colin King <colin.king@canonical.com>
Cc: linux-fbdev@vger.kernel.org, Jani Nikula <jani.nikula@intel.com>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org,
dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] video: fbdev: fix setting of pixclock because a pass-by-value error
Date: Tue, 08 Sep 2020 11:36:43 +0000 [thread overview]
Message-ID: <ed082436-9ce3-23fd-679c-9cdf7b1da0cd@samsung.com> (raw)
In-Reply-To: <20200723170227.996229-1-colin.king@canonical.com>
On 7/23/20 7:02 PM, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> 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")
> Fixes: 115f4504a64a ("Removed currcon and other console related code. Very little is now left.")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
Applied to drm-misc-next tree, thanks and sorry for the delay.
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics
> ---
> 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 a20eeb8308ff..52f273af6cae 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;
>
prev parent reply other threads:[~2020-09-08 11:36 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20200723170235eucas1p21b1e0f5ff092d550d65057ae2a31a897@eucas1p2.samsung.com>
2020-07-23 17:02 ` [PATCH] video: fbdev: fix setting of pixclock because a pass-by-value error Colin King
2020-09-08 11:36 ` Bartlomiej Zolnierkiewicz [this message]
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