* [PATCH] video: fbdev: fix setting of pixclock because a pass-by-value error @ 2020-07-23 17:02 ` Colin King 2020-09-08 11:36 ` Bartlomiej Zolnierkiewicz 0 siblings, 1 reply; 2+ messages in thread From: Colin King @ 2020-07-23 17:02 UTC (permalink / raw) To: Bartlomiej Zolnierkiewicz, Daniel Vetter, Jani Nikula, dri-devel, linux-fbdev Cc: kernel-janitors, linux-kernel 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 ^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] video: fbdev: fix setting of pixclock because a pass-by-value error 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 0 siblings, 0 replies; 2+ messages in thread From: Bartlomiej Zolnierkiewicz @ 2020-09-08 11:36 UTC (permalink / raw) To: Colin King Cc: Daniel Vetter, Jani Nikula, dri-devel, linux-fbdev, kernel-janitors, linux-kernel 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; > ^ permalink raw reply [flat|nested] 2+ messages in thread
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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
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