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| Started by | Andrew Jeffery <andrew@aj.id.au> |
|---|---|
| First post | 2017-09-18 08:00 +0200 |
| Last post | 2017-09-20 04:40 +0200 |
| Articles | 5 — 3 participants |
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[PATCH 1/4] watchdog: aspeed: Retain watchdog enabled state Andrew Jeffery <andrew@aj.id.au> - 2017-09-18 08:00 +0200
Re: [PATCH 1/4] watchdog: aspeed: Retain watchdog enabled state Guenter Roeck <linux@roeck-us.net> - 2017-09-18 15:30 +0200
Re: [PATCH 1/4] watchdog: aspeed: Retain watchdog enabled state Andrew Jeffery <andrew@aj.id.au> - 2017-09-19 04:40 +0200
Re: [PATCH 1/4] watchdog: aspeed: Retain watchdog enabled state Joel Stanley <joel@jms.id.au> - 2017-09-20 03:50 +0200
Re: [PATCH 1/4] watchdog: aspeed: Retain watchdog enabled state Andrew Jeffery <andrew@aj.id.au> - 2017-09-20 04:40 +0200
| From | Andrew Jeffery <andrew@aj.id.au> |
|---|---|
| Date | 2017-09-18 08:00 +0200 |
| Subject | [PATCH 1/4] watchdog: aspeed: Retain watchdog enabled state |
| Message-ID | <uqXg5-1HP-1@gated-at.bofh.it> |
An unintended post-condition of probe() is that the watchdog is
disabled. Rework probe() such that we retain the value of the "enabled"
bit from the control register, and take the appropriate actions with
respect to the watchdog core if so. Otherwise, just configure the
watchdog as directed.
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
---
drivers/watchdog/aspeed_wdt.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
index 79cc766cd30f..99bc6fbd8852 100644
--- a/drivers/watchdog/aspeed_wdt.c
+++ b/drivers/watchdog/aspeed_wdt.c
@@ -221,7 +221,8 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
return -EINVAL;
config = ofdid->data;
- wdt->ctrl = WDT_CTRL_1MHZ_CLK;
+ wdt->ctrl |= readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE;
+ wdt->ctrl |= WDT_CTRL_1MHZ_CLK;
/*
* Control reset on a per-device basis to ensure the
@@ -243,11 +244,11 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
if (of_property_read_bool(np, "aspeed,external-signal"))
wdt->ctrl |= WDT_CTRL_WDT_EXT;
- writel(wdt->ctrl, wdt->base + WDT_CTRL);
-
- if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE) {
+ if (wdt->ctrl & WDT_CTRL_ENABLE) {
aspeed_wdt_start(&wdt->wdd);
set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
+ } else {
+ writel(wdt->ctrl, wdt->base + WDT_CTRL);
}
if (of_device_is_compatible(np, "aspeed,ast2500-wdt")) {
--
2.11.0
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| From | Guenter Roeck <linux@roeck-us.net> |
|---|---|
| Date | 2017-09-18 15:30 +0200 |
| Message-ID | <ur4hA-6QH-27@gated-at.bofh.it> |
| In reply to | #1733648 |
On 09/17/2017 10:49 PM, Andrew Jeffery wrote:
> An unintended post-condition of probe() is that the watchdog is
> disabled. Rework probe() such that we retain the value of the "enabled"
> bit from the control register, and take the appropriate actions with
> respect to the watchdog core if so. Otherwise, just configure the
> watchdog as directed.
>
> Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
> ---
> drivers/watchdog/aspeed_wdt.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> index 79cc766cd30f..99bc6fbd8852 100644
> --- a/drivers/watchdog/aspeed_wdt.c
> +++ b/drivers/watchdog/aspeed_wdt.c
> @@ -221,7 +221,8 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
> return -EINVAL;
> config = ofdid->data;
>
> - wdt->ctrl = WDT_CTRL_1MHZ_CLK;
> + wdt->ctrl |= readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE;
> + wdt->ctrl |= WDT_CTRL_1MHZ_CLK;
>
> /*
> * Control reset on a per-device basis to ensure the
> @@ -243,11 +244,11 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
> if (of_property_read_bool(np, "aspeed,external-signal"))
> wdt->ctrl |= WDT_CTRL_WDT_EXT;
>
> - writel(wdt->ctrl, wdt->base + WDT_CTRL);
> -
> - if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE) {
> + if (wdt->ctrl & WDT_CTRL_ENABLE) {
> aspeed_wdt_start(&wdt->wdd);
Why call the start function in this case ?
> set_bit(WDOG_HW_RUNNING, &wdt->wdd.status); > + } else {
> + writel(wdt->ctrl, wdt->base + WDT_CTRL);
> }
>
> if (of_device_is_compatible(np, "aspeed,ast2500-wdt")) {
>
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| From | Andrew Jeffery <andrew@aj.id.au> |
|---|---|
| Date | 2017-09-19 04:40 +0200 |
| Message-ID | <urgC5-6EL-1@gated-at.bofh.it> |
| In reply to | #1734116 |
[Multipart message — attachments visible in raw view] — view raw
On Mon, 2017-09-18 at 06:25 -0700, Guenter Roeck wrote:
> On 09/17/2017 10:49 PM, Andrew Jeffery wrote:
> > An unintended post-condition of probe() is that the watchdog is
> > disabled. Rework probe() such that we retain the value of the "enabled"
> > bit from the control register, and take the appropriate actions with
> > respect to the watchdog core if so. Otherwise, just configure the
> > watchdog as directed.
> >
> > > > Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
> > ---
> > drivers/watchdog/aspeed_wdt.c | 9 +++++----
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> > index 79cc766cd30f..99bc6fbd8852 100644
> > --- a/drivers/watchdog/aspeed_wdt.c
> > +++ b/drivers/watchdog/aspeed_wdt.c
> > @@ -221,7 +221,8 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
> > > > return -EINVAL;
> > > > config = ofdid->data;
> >
> > > > - wdt->ctrl = WDT_CTRL_1MHZ_CLK;
> > > > + wdt->ctrl |= readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE;
> > > > + wdt->ctrl |= WDT_CTRL_1MHZ_CLK;
> >
> > > > /*
> > > > * Control reset on a per-device basis to ensure the
> > @@ -243,11 +244,11 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
> > > > if (of_property_read_bool(np, "aspeed,external-signal"))
> > > > wdt->ctrl |= WDT_CTRL_WDT_EXT;
> >
> > > > - writel(wdt->ctrl, wdt->base + WDT_CTRL);
> > -
> > > > - if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE) {
> > > > + if (wdt->ctrl & WDT_CTRL_ENABLE) {
> > aspeed_wdt_start(&wdt->wdd);
>
> Why call the start function in this case ?
... Good question. It was already there so I didn't touch it. I expect
it can be dropped - I'll look into it.
>
> > > > > > set_bit(WDOG_HW_RUNNING, &wdt->wdd.status); > + } else {
> > > > + writel(wdt->ctrl, wdt->base + WDT_CTRL);
> > > > }
> >
> > > > if (of_device_is_compatible(np, "aspeed,ast2500-wdt")) {
> >
>
>
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| From | Joel Stanley <joel@jms.id.au> |
|---|---|
| Date | 2017-09-20 03:50 +0200 |
| Message-ID | <urCjf-4CT-5@gated-at.bofh.it> |
| In reply to | #1733648 |
On Mon, Sep 18, 2017 at 3:19 PM, Andrew Jeffery <andrew@aj.id.au> wrote:
> An unintended post-condition of probe() is that the watchdog is
> disabled. Rework probe() such that we retain the value of the "enabled"
> bit from the control register, and take the appropriate actions with
> respect to the watchdog core if so. Otherwise, just configure the
> watchdog as directed.
>
This should have a fixes line. The code as it stands in 4.14-rc1
unconditionally disables the watchdog at boot :(
> Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
> ---
> drivers/watchdog/aspeed_wdt.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> index 79cc766cd30f..99bc6fbd8852 100644
> --- a/drivers/watchdog/aspeed_wdt.c
> +++ b/drivers/watchdog/aspeed_wdt.c
> @@ -221,7 +221,8 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
> return -EINVAL;
> config = ofdid->data;
>
> - wdt->ctrl = WDT_CTRL_1MHZ_CLK;
> + wdt->ctrl |= readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE;
If we go back to before b7f0b8ad25f3 ("drivers/watchdog: ASPEED
reference dev tree properties for config"), the driver set up the
cached ctrl value and then tested the hardware state to decide if we
should have the watchdog enabled.
Looking at the driver now there's little reason to keep the cached
ctrl value. I'd suggest reworking the driver to not have it so we can
avoid bugs like the ones that b7f0b8ad25f3 introduced.
Cheers,
Joel
> + wdt->ctrl |= WDT_CTRL_1MHZ_CLK;
>
> /*
> * Control reset on a per-device basis to ensure the
> @@ -243,11 +244,11 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
> if (of_property_read_bool(np, "aspeed,external-signal"))
> wdt->ctrl |= WDT_CTRL_WDT_EXT;
>
> - writel(wdt->ctrl, wdt->base + WDT_CTRL);
> -
> - if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE) {
> + if (wdt->ctrl & WDT_CTRL_ENABLE) {
> aspeed_wdt_start(&wdt->wdd);
> set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
> + } else {
> + writel(wdt->ctrl, wdt->base + WDT_CTRL);
> }
>
> if (of_device_is_compatible(np, "aspeed,ast2500-wdt")) {
> --
> 2.11.0
>
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| From | Andrew Jeffery <andrew@aj.id.au> |
|---|---|
| Date | 2017-09-20 04:40 +0200 |
| Message-ID | <urD5E-5dE-5@gated-at.bofh.it> |
| In reply to | #1735393 |
[Multipart message — attachments visible in raw view] — view raw
On Wed, 2017-09-20 at 11:17 +0930, Joel Stanley wrote:
> > On Mon, Sep 18, 2017 at 3:19 PM, Andrew Jeffery <andrew@aj.id.au> wrote:
> > An unintended post-condition of probe() is that the watchdog is
> > disabled. Rework probe() such that we retain the value of the "enabled"
> > bit from the control register, and take the appropriate actions with
> > respect to the watchdog core if so. Otherwise, just configure the
> > watchdog as directed.
> >
>
> This should have a fixes line. The code as it stands in 4.14-rc1
> unconditionally disables the watchdog at boot :(
I'll add a fixes line.
>
> > > > Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
> > ---
> > drivers/watchdog/aspeed_wdt.c | 9 +++++----
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> > index 79cc766cd30f..99bc6fbd8852 100644
> > --- a/drivers/watchdog/aspeed_wdt.c
> > +++ b/drivers/watchdog/aspeed_wdt.c
> > @@ -221,7 +221,8 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
> > return -EINVAL;
> > config = ofdid->data;
> >
> > - wdt->ctrl = WDT_CTRL_1MHZ_CLK;
> > + wdt->ctrl |= readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE;
>
> If we go back to before b7f0b8ad25f3 ("drivers/watchdog: ASPEED
> reference dev tree properties for config"), the driver set up the
> cached ctrl value and then tested the hardware state to decide if we
> should have the watchdog enabled.
>
> Looking at the driver now there's little reason to keep the cached
> ctrl value. I'd suggest reworking the driver to not have it so we can
> avoid bugs like the ones that b7f0b8ad25f3 introduced.
Alternatively, we can just drop the write I moved to the else branch
and rely on aspeed_wdt_start() to configure the control register for
us.
Guenter: This means we retain the call you questioned. It's name might
be slightly misleading in terms of the effect it gives us (configuring
the watchdog to match the driver's assumptions), but doing it that way
effectively turns my original patch into a one-liner to delete the
writel(). If the watchdog is disabled at the point of kernel
initialisation then the configuration doesn't matter until userspace
opens the chardev, at which point we'll write the configuration via
aspeed_wdt_start() anyway.
Andrew
>
> Cheers,
>
> Joel
>
> > + wdt->ctrl |= WDT_CTRL_1MHZ_CLK;
> >
> > /*
> > * Control reset on a per-device basis to ensure the
> > @@ -243,11 +244,11 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
> > if (of_property_read_bool(np, "aspeed,external-signal"))
> > wdt->ctrl |= WDT_CTRL_WDT_EXT;
> >
> > - writel(wdt->ctrl, wdt->base + WDT_CTRL);
> > -
> > - if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE) {
> > + if (wdt->ctrl & WDT_CTRL_ENABLE) {
> > aspeed_wdt_start(&wdt->wdd);
> > set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
> > + } else {
> > + writel(wdt->ctrl, wdt->base + WDT_CTRL);
> > }
> >
> > if (of_device_is_compatible(np, "aspeed,ast2500-wdt")) {
> > --
> > 2.11.0
> >
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