Re: [PATCH] fbdev: radeon: Remove 'struct timeval' usage

On 3 June 2015 at 21:59, Tomi Valkeinen [off-list ref] wrote:

On 25/05/15 07:07, Tina Ruchandani wrote:

quoted

'struct timeval' uses a 32-bit representation for the
seconds field which will overflow in the year 2038 and beyond.
This patch replaces the usage of 'struct timeval' with
ktime_t which uses a 64-bit time representation and does not
suffer from the y2038 problem. This patch is part of a larger
effort to remove all instances of 'struct timeval', 'struct
timespec', time_t and other 32-bit timekeeping variables
from the kernel.
The patch also replaces the use of real time (do_gettimeofday)
with monotonic time (ktime_get).

Signed-off-by: Tina Ruchandani <redacted>
---
 drivers/video/fbdev/aty/radeon_base.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/drivers/video/fbdev/aty/radeon_base.c b/drivers/video/fbdev/aty/radeon_base.c
index 01237c8..9747e9e 100644
--- a/drivers/video/fbdev/aty/radeon_base.c
+++ b/drivers/video/fbdev/aty/radeon_base.c

@@ -64,6 +64,7 @@
 #include <linux/slab.h>
 #include <linux/delay.h>
 #include <linux/time.h>
+#include <linux/ktime.h>
 #include <linux/fb.h>
 #include <linux/ioport.h>
 #include <linux/init.h>

@@ -461,8 +462,8 @@ static int radeon_probe_pll_params(struct radeonfb_info *rinfo)
      int hTotal, vTotal, num, denom, m, n;
      unsigned long long hz, vclk;
      long xtal;
-     struct timeval start_tv, stop_tv;
-     long total_secs, total_usecs;
+     ktime_t start, stop;
+     s64 delta;
      int i;

      /* Ugh, we cut interrupts, bad bad bad, but we want some precision

@@ -478,7 +479,7 @@ static int radeon_probe_pll_params(struct radeonfb_info *rinfo)
              if (((INREG(CRTC_VLINE_CRNT_VLINE) >> 16) & 0x3ff) = 0)
                      break;

-     do_gettimeofday(&start_tv);
+     start = ktime_get();

      for(i=0; i<1000000; i++)
              if (((INREG(CRTC_VLINE_CRNT_VLINE) >> 16) & 0x3ff) != 0)

@@ -487,20 +488,18 @@ static int radeon_probe_pll_params(struct radeonfb_info *rinfo)
      for(i=0; i<1000000; i++)
              if (((INREG(CRTC_VLINE_CRNT_VLINE) >> 16) & 0x3ff) = 0)
                      break;
-
-     do_gettimeofday(&stop_tv);
-
+
+     stop = ktime_get();
+
      local_irq_enable();

-     total_secs = stop_tv.tv_sec - start_tv.tv_sec;
-     if (total_secs > 10)
+     delta = ktime_us_delta(stop, start);
+
+     /* Return -1 if more than 10 seconds have elapsed */
+     if (delta > (10*1000000))
              return -1;
-     total_usecs = stop_tv.tv_usec - start_tv.tv_usec;
-     total_usecs += total_secs * 1000000;
-     if (total_usecs < 0)
-             total_usecs = -total_usecs;
-     hz = 1000000/total_usecs;
-
+     hz = 1000000/delta;

This needs to be on of the do_div family.

Dave.