From: Colin King <colin.king@canonical.com>
To: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
Jani Nikula <jani.nikula@intel.com>,
dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org
Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] video: fbdev: fix setting of pixclock because a pass-by-value error
Date: Thu, 23 Jul 2020 18:02:27 +0100 [thread overview]
Message-ID: <20200723170227.996229-1-colin.king@canonical.com> (raw)
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>
---
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;
--
2.27.0
next reply other threads:[~2020-07-23 17:02 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 ` Colin King [this message]
2020-09-08 11:36 ` Bartlomiej Zolnierkiewicz
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