Re: s3c2410fb: fix clockrate calculation
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2009-08-20 22:19:59
On Thu, 20 Aug 2009 22:50:47 +0100 Ben Dooks [off-list ref] wrote:
quoted hunk ↗ jump to hunk
In the final part of the calculation for the tft display clockrate we divide the output pf s3c2410fb_calc_pixclk() by 2 which leaves us with a rounding error if the result is odd. Change to using DIV_ROUND_UP() to ensure that we always choose a higher divisor and thus a lower frequency. Signed-off-by: Ben Dooks <redacted> --- drivers/video/s3c2410fb.c | 4 +++- 2 files changed, 5 insertions(+), 2 deletions(-) Index: b/drivers/video/s3c2410fb.c ===================================================================--- a/drivers/video/s3c2410fb.c 2009-08-20 08:45:41.000000000 +0100 +++ b/drivers/video/s3c2410fb.c 2009-08-20 08:45:42.000000000 +0100@@ -369,7 +369,9 @@ static void s3c2410fb_activate_var(struc void __iomem *regs = fbi->io; int type = fbi->regs.lcdcon1 & S3C2410_LCDCON1_TFT; struct fb_var_screeninfo *var = &info->var; - int clkdiv = s3c2410fb_calc_pixclk(fbi, var->pixclock) / 2; + int clkdiv; + + clkdiv = DIV_ROUND_UP(s3c2410fb_calc_pixclk(fbi, var->pixclock), 2); printk(KERN_INFO "%s: pixclock=%d, clkdiv=%d\n", __func__, var->pixclock, clkdiv);
The changelog forgot to tell us what the impact of this bug is, so I cannot work out whether we need this fix in 2.6.32, 2.6.31, 2.6.30.x, .... ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july