From patchwork Sat Aug 18 08:10:08 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: rtc: snvs: improve timeout handling in snvs_rtc_enable() Date: Fri, 17 Aug 2012 22:10:08 -0000 From: =?utf-8?q?Lothar_Wa=C3=9Fmann?= X-Patchwork-Id: 178432 Message-Id: <1345277408-30044-1-git-send-email-LW@KARO-electronics.de> To: rtc-linux@googlegroups.com Cc: =?UTF-8?q?Lothar=20Wa=C3=9Fmann?= , Andrew Morton , Shawn Guo , Alessandro Zummo , Kim Phillips , Sascha Hauer , Stephen Boyd , linux-arm-kernel@lists.infradead.org If snvs_rtc_enable() happens to be descheduled for a period longer than the timout period, a timeout may be indicated even if the RTC status has changed meanwhile. Force a status read at the end of the timeout period to prevent bogus timeout errors. Signed-off-by: Lothar Waßmann Tested-by: Shawn Guo --- drivers/rtc/rtc-snvs.c | 22 +++++++++++++--------- 1 files changed, 13 insertions(+), 9 deletions(-) Compile tested only due to lack of HW. diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c index 912f116..dc921b2 100644 --- a/drivers/rtc/rtc-snvs.c +++ b/drivers/rtc/rtc-snvs.c @@ -81,6 +81,13 @@ static void rtc_write_sync_lp(void __iomem *ioaddr) } } +static int snvs_rtc_enable_done(int enable, void __iomem *addr) +{ + u32 lpcr = readl(addr + SNVS_LPCR); + + return !!enable ^ !(lpcr & SNVS_LPCR_SRTC_ENV); +} + static int snvs_rtc_enable(struct snvs_rtc_data *data, bool enable) { unsigned long timeout = jiffies + msecs_to_jiffies(1); @@ -99,18 +106,15 @@ static int snvs_rtc_enable(struct snvs_rtc_data *data, bool enable) spin_unlock_irqrestore(&data->lock, flags); while (1) { - lpcr = readl(data->ioaddr + SNVS_LPCR); + if (snvs_rtc_enable_done(enable, data->ioaddr)) + break; - if (enable) { - if (lpcr & SNVS_LPCR_SRTC_ENV) - break; - } else { - if (!(lpcr & SNVS_LPCR_SRTC_ENV)) + if (time_after(jiffies, timeout)) { + if (snvs_rtc_enable_done(enable, data->ioaddr)) break; + else + return -ETIMEDOUT; } - - if (time_after(jiffies, timeout)) - return -ETIMEDOUT; } return 0;