From patchwork Sat Aug 18 13:14:04 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: Sat, 18 Aug 2012 03:14:04 -0000 From: =?utf-8?q?Lothar_Wa=C3=9Fmann?= X-Patchwork-Id: 178466 Message-Id: <20527.38172.621130.368019@ipc1.ka-ro> To: Shawn Guo Cc: Alessandro Zummo , Kim Phillips , rtc-linux@googlegroups.com, Sascha Hauer , Stephen Boyd , Andrew Morton , linux-arm-kernel@lists.infradead.org Shawn Guo writes: > On Sat, Aug 18, 2012 at 10:10:08AM +0200, Lothar Waßmann wrote: > > 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 > > --- > > drivers/rtc/rtc-snvs.c | 22 +++++++++++++--------- > > 1 files changed, 13 insertions(+), 9 deletions(-) > > > > Compile tested only due to lack of HW. > > Tested-by: Shawn Guo > > A small nitpick below. > > > > > 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) > > Can we rename parameter "addr" to "ioaddr" and put it before "enable", > also change "enable" to bool? > OK. The resulting assembler code of the patch below is identical to the previous version of this patch. Signed-off-by: Lothar Waßmann Tested-by: Shawn Guo --- drivers/rtc/rtc-snvs.c | 22 +++++++++++++--------- 1 files changed, 13 insertions(+), 9 deletions(-) diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c index 912f116..a757cb9 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(void __iomem *ioaddr, bool enable) +{ + u32 lpcr = readl(ioaddr + 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(data->ioaddr, enable)) + 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(data->ioaddr, enable)) break; + else + return -ETIMEDOUT; } - - if (time_after(jiffies, timeout)) - return -ETIMEDOUT; } return 0;