| Message ID | 20170918054905.16470-2-andrew@aj.id.au |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | watchdog: aspeed: Retain enabled state and move to | expand |
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")) { >
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")) { > > > >
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 >
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 > >
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")) {
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(-)