| Message ID | 20201026080919.28413-1-zhang.lyra@gmail.com |
|---|---|
| Headers | show |
| Series | A few fixes to sprd watchdog driver | expand |
On 10/26/20 1:09 AM, Chunyan Zhang wrote: > From: Lingling Xu <ling_ling.xu@unisoc.com> > > Don't disable watchdog in resume process, otherwise system would crash > once kick watchdog. > This is a bit misleading: It is only disabled if the attempt to start it has failed. Was this observed in practice ? If so, it might make sense to identify and fix the underlying problem instead of trying to work around it (or is this addressed with the second patch of the series ?) Anyway, the patch itself is fine. Reviewed-by: Guenter Roeck <linux@roeck-us.net> Thanks, Guenter > Fixes: 477603467009 ("watchdog: Add Spreadtrum watchdog driver") > Signed-off-by: Lingling Xu <ling_ling.xu@unisoc.com> > Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com> > --- > drivers/watchdog/sprd_wdt.c | 9 ++------- > 1 file changed, 2 insertions(+), 7 deletions(-) > > diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c > index 65cb55f3916f..f3c90b4afead 100644 > --- a/drivers/watchdog/sprd_wdt.c > +++ b/drivers/watchdog/sprd_wdt.c > @@ -345,15 +345,10 @@ static int __maybe_unused sprd_wdt_pm_resume(struct device *dev) > if (ret) > return ret; > > - if (watchdog_active(&wdt->wdd)) { > + if (watchdog_active(&wdt->wdd)) > ret = sprd_wdt_start(&wdt->wdd); > - if (ret) { > - sprd_wdt_disable(wdt); > - return ret; > - } > - } > > - return 0; > + return ret; > } > > static const struct dev_pm_ops sprd_wdt_pm_ops = { >
On 10/26/20 1:09 AM, Chunyan Zhang wrote: > From: Lingling Xu <ling_ling.xu@unisoc.com> > > As the specification described, checking busy bit must be done before kick > watchdog. > That is a key functional change: So far the code checked if a value was accepted after loading it. That is no longer the case. Effectively, with this change, the _next_ operation will now check if the previous operation was accepted. Is this intentional ? Also, does this really solve a problem, or is it just an optimization ? By checking for busy prior to an operation instead of after it the only real difference is that the busy check will most likely succeed immediately because enough time has passed since the last write. Ultimately it is your call how you want to handle this, but I think the impact should be spelled out. Guenter > Fixes: 477603467009 ("watchdog: Add Spreadtrum watchdog driver") > Signed-off-by: Lingling Xu <ling_ling.xu@unisoc.com> > Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com> > --- > drivers/watchdog/sprd_wdt.c | 27 ++++++++++++++------------- > 1 file changed, 14 insertions(+), 13 deletions(-) > > diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c > index 4f2a8c6d6485..14071c66ff49 100644 > --- a/drivers/watchdog/sprd_wdt.c > +++ b/drivers/watchdog/sprd_wdt.c > @@ -108,20 +108,8 @@ static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout, > u32 tmr_step = timeout * SPRD_WDT_CNT_STEP; > u32 prtmr_step = pretimeout * SPRD_WDT_CNT_STEP; > > - sprd_wdt_unlock(wdt->base); > - writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) & > - SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH); > - writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK), > - wdt->base + SPRD_WDT_LOAD_LOW); > - writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) & > - SPRD_WDT_LOW_VALUE_MASK, > - wdt->base + SPRD_WDT_IRQ_LOAD_HIGH); > - writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK, > - wdt->base + SPRD_WDT_IRQ_LOAD_LOW); > - sprd_wdt_lock(wdt->base); > - > /* > - * Waiting the load value operation done, > + * Waiting the last load value operation done, > * it needs two or three RTC clock cycles. > */ > do { > @@ -134,6 +122,19 @@ static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout, > > if (delay_cnt >= SPRD_WDT_LOAD_TIMEOUT) > return -EBUSY; > + > + sprd_wdt_unlock(wdt->base); > + writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) & > + SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH); > + writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK), > + wdt->base + SPRD_WDT_LOAD_LOW); > + writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) & > + SPRD_WDT_LOW_VALUE_MASK, > + wdt->base + SPRD_WDT_IRQ_LOAD_HIGH); > + writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK, > + wdt->base + SPRD_WDT_IRQ_LOAD_LOW); > + sprd_wdt_lock(wdt->base); > + > return 0; > } > >
On Mon, 26 Oct 2020 at 22:44, Guenter Roeck <linux@roeck-us.net> wrote: > > On 10/26/20 1:09 AM, Chunyan Zhang wrote: > > From: Lingling Xu <ling_ling.xu@unisoc.com> > > > > As the specification described, checking busy bit must be done before kick > > watchdog. > > > > That is a key functional change: So far the code checked if a value > was accepted after loading it. That is no longer the case. Effectively, > with this change, the _next_ operation will now check if the previous > operation was accepted. Is this intentional ? Yes, the busy bit indicates whether the previous operation is done, so we have to make sure the last loading completed (the busy bit is not set) before new loading. The spec says that this bit is set after a new loading, and would last 2 or 3 RTC clock cycles. > > Also, does this really solve a problem, or is it just an optimization ? > By checking for busy prior to an operation instead of after it the only > real difference is that the busy check will most likely succeed immediately > because enough time has passed since the last write. > > Ultimately it is your call how you want to handle this, but I think the > impact should be spelled out. Ok, I will add more details in the commit message. Many thanks for the review! Chunyan > > Guenter > > > Fixes: 477603467009 ("watchdog: Add Spreadtrum watchdog driver") > > Signed-off-by: Lingling Xu <ling_ling.xu@unisoc.com> > > Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com> > > --- > > drivers/watchdog/sprd_wdt.c | 27 ++++++++++++++------------- > > 1 file changed, 14 insertions(+), 13 deletions(-) > > > > diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c > > index 4f2a8c6d6485..14071c66ff49 100644 > > --- a/drivers/watchdog/sprd_wdt.c > > +++ b/drivers/watchdog/sprd_wdt.c > > @@ -108,20 +108,8 @@ static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout, > > u32 tmr_step = timeout * SPRD_WDT_CNT_STEP; > > u32 prtmr_step = pretimeout * SPRD_WDT_CNT_STEP; > > > > - sprd_wdt_unlock(wdt->base); > > - writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) & > > - SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH); > > - writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK), > > - wdt->base + SPRD_WDT_LOAD_LOW); > > - writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) & > > - SPRD_WDT_LOW_VALUE_MASK, > > - wdt->base + SPRD_WDT_IRQ_LOAD_HIGH); > > - writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK, > > - wdt->base + SPRD_WDT_IRQ_LOAD_LOW); > > - sprd_wdt_lock(wdt->base); > > - > > /* > > - * Waiting the load value operation done, > > + * Waiting the last load value operation done, > > * it needs two or three RTC clock cycles. > > */ > > do { > > @@ -134,6 +122,19 @@ static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout, > > > > if (delay_cnt >= SPRD_WDT_LOAD_TIMEOUT) > > return -EBUSY; > > + > > + sprd_wdt_unlock(wdt->base); > > + writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) & > > + SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH); > > + writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK), > > + wdt->base + SPRD_WDT_LOAD_LOW); > > + writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) & > > + SPRD_WDT_LOW_VALUE_MASK, > > + wdt->base + SPRD_WDT_IRQ_LOAD_HIGH); > > + writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK, > > + wdt->base + SPRD_WDT_IRQ_LOAD_LOW); > > + sprd_wdt_lock(wdt->base); > > + > > return 0; > > } > > > > >
On Mon, 26 Oct 2020 at 22:27, Guenter Roeck <linux@roeck-us.net> wrote: > > On 10/26/20 1:09 AM, Chunyan Zhang wrote: > > From: Lingling Xu <ling_ling.xu@unisoc.com> > > > > Don't disable watchdog in resume process, otherwise system would crash > > once kick watchdog. > > > > This is a bit misleading: It is only disabled if the attempt to start it > has failed. Was this observed in practice ? If so, it might make sense > to identify and fix the underlying problem instead of trying to work > around it (or is this addressed with the second patch of the series ?) Yes, I think the root cause of this problem was like what I explained in the 3rd patch in this series. Lingling found there was something wrong in sprd_wdt_pm_resume() when debugging that issue, then we had this patch. > > Anyway, the patch itself is fine. > > Reviewed-by: Guenter Roeck <linux@roeck-us.net> Thanks, Chunyan > > Thanks, > Guenter > > > Fixes: 477603467009 ("watchdog: Add Spreadtrum watchdog driver") > > Signed-off-by: Lingling Xu <ling_ling.xu@unisoc.com> > > Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com> > > --- > > drivers/watchdog/sprd_wdt.c | 9 ++------- > > 1 file changed, 2 insertions(+), 7 deletions(-) > > > > diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c > > index 65cb55f3916f..f3c90b4afead 100644 > > --- a/drivers/watchdog/sprd_wdt.c > > +++ b/drivers/watchdog/sprd_wdt.c > > @@ -345,15 +345,10 @@ static int __maybe_unused sprd_wdt_pm_resume(struct device *dev) > > if (ret) > > return ret; > > > > - if (watchdog_active(&wdt->wdd)) { > > + if (watchdog_active(&wdt->wdd)) > > ret = sprd_wdt_start(&wdt->wdd); > > - if (ret) { > > - sprd_wdt_disable(wdt); > > - return ret; > > - } > > - } > > > > - return 0; > > + return ret; > > } > > > > static const struct dev_pm_ops sprd_wdt_pm_ops = { > > >
From: Chunyan Zhang <chunyan.zhang@unisoc.com> A few issues about sprd watchdog driver were found recently, this patchset would fix them. Lingling Xu (3): watchdog: sprd: should not disable watchdog in resume watchdog: sprd: change timeout value from 1000 to 2000 watchdog: sprd: check busy bit before kick watchdog drivers/watchdog/sprd_wdt.c | 38 +++++++++++++++++-------------------- 1 file changed, 17 insertions(+), 21 deletions(-)