Hi Arnd,
On 6/13/2016 1:40 PM, Arnd Bergmann wrote:
I could not figure out why, but gcc cannot prove that the
kona_timer_init function always initializes its two outputs,
and we get a warning for the use of the 'lsw' variable later,
which is obviously correct.
drivers/clocksource/bcm_kona_timer.c: In function 'kona_timer_init':
drivers/clocksource/bcm_kona_timer.c:119:13: error: 'lsw' may be used
uninitialized in this function [-Werror=maybe-uninitialized]
Slightly reordering the loop makes the warning disappear, after
it becomes more obvious to the compiler that the loop is
always entered on the first iteration.
Signed-off-by: Arnd Bergmann <a...@arndb.de>
---
drivers/clocksource/bcm_kona_timer.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/clocksource/bcm_kona_timer.c
b/drivers/clocksource/bcm_kona_timer.c
index 70d9c1e482dd..bbbfb03b46dd 100644
--- a/drivers/clocksource/bcm_kona_timer.c
+++ b/drivers/clocksource/bcm_kona_timer.c
@@ -69,7 +69,7 @@ static void kona_timer_disable_and_clear(void __iomem *base)
static void
kona_timer_get_counter(void __iomem *timer_base, uint32_t *msw, uint32_t *lsw)
{
- int loop_limit = 4;
+ int loop_limit = 3;
/*
* Read 64-bit free running counter
@@ -83,12 +83,12 @@ kona_timer_get_counter(void __iomem *timer_base, uint32_t
*msw, uint32_t *lsw)
* if new hi-word is equal to previously read hi-word then stop.
*/
- while (--loop_limit) {
+ do {
*msw = readl(timer_base + KONA_GPTIMER_STCHI_OFFSET);
*lsw = readl(timer_base + KONA_GPTIMER_STCLO_OFFSET);
if (*msw == readl(timer_base + KONA_GPTIMER_STCHI_OFFSET))
break;
- }
+ } while (--loop_limit);
if (!loop_limit) {
pr_err("bcm_kona_timer: getting counter failed.\n");
pr_err(" Timer will be impacted\n");
This fix of compiler warning looks fine to me.
Btw, this also exposes another issue in the code:
Does it make more sense to have "kona_timer_get_counter" return
-ETIMEDOUT in the case when "loop_limit" reaches zero, and in
"kona_timer_set_net_event", it should bail out immediately when error is
returned from "kona_timer_get_counter":
ret = kona_timer_get_counter(timers.tmr_regs, &msw, &lsw);
if (ret)
return ret;
Thanks,
Ray
