| Message ID | 20201219173415.21848-1-wsa+renesas@sang-engineering.com |
|---|---|
| State | New |
| Headers | show |
| Series | watchdog: renesas_wdt: don't sleep in atomic context | expand |
On 12/19/20 9:34 AM, Wolfram Sang wrote: > In the restart handler, we hit multiple OOPSes. One because of > usleep_range() and one because of RPM. So, instead of re-using > rwdt_start(), we implement an atomic version of it in the restart > handler. As a little bonus, reboot will occur sooner because we can now > use the smallest divider in the custom restart routine. > > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> > --- > > It is problematic to add a Fixes: tag because we would need three of > them. So, I'd think we add a stable tag and as long as the patch > applies, all is fine. Other opinions? > > drivers/watchdog/renesas_wdt.c | 30 ++++++++++++++++++++++++------ > 1 file changed, 24 insertions(+), 6 deletions(-) > > diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c > index 47fce4de0110..d2b5074bca65 100644 > --- a/drivers/watchdog/renesas_wdt.c > +++ b/drivers/watchdog/renesas_wdt.c > @@ -9,6 +9,7 @@ > #include <linux/clk.h> > #include <linux/delay.h> > #include <linux/io.h> > +#include <linux/iopoll.h> > #include <linux/kernel.h> > #include <linux/module.h> > #include <linux/of.h> > @@ -50,6 +51,7 @@ struct rwdt_priv { > struct watchdog_device wdev; > unsigned long clk_rate; > u8 cks; > + struct clk *clk; > }; > > static void rwdt_write(struct rwdt_priv *priv, u32 val, unsigned int reg) > @@ -125,13 +127,30 @@ static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev) > return DIV_BY_CLKS_PER_SEC(priv, 65536 - val); > } > > +/* needs to be atomic - no RPM, no usleep_range, no scheduling! */ > static int rwdt_restart(struct watchdog_device *wdev, unsigned long action, > void *data) > { > struct rwdt_priv *priv = watchdog_get_drvdata(wdev); > + u8 val; > + > + clk_prepare_enable(priv->clk); > + > + /* Stop the timer before we modify any register */ > + val = readb_relaxed(priv->base + RWTCSRA) & ~RWTCSRA_TME; > + rwdt_write(priv, val, RWTCSRA); > + /* Delay 2 cycles before setting watchdog counter */ > + udelay(DIV_ROUND_UP(2 * 1000000, priv->clk_rate)); > > - rwdt_start(wdev); > rwdt_write(priv, 0xffff, RWTCNT); > + /* smallest divider to reboot soon */ > + rwdt_write(priv, 0, RWTCSRA); > + > + readb_poll_timeout_atomic(priv->base + RWTCSRA, val, > + !(val & RWTCSRA_WRFLG), 1, 100); > + > + rwdt_write(priv, RWTCSRA_TME, RWTCSRA); > + > return 0; > } > > @@ -191,7 +210,6 @@ static int rwdt_probe(struct platform_device *pdev) > { > struct device *dev = &pdev->dev; > struct rwdt_priv *priv; > - struct clk *clk; > unsigned long clks_per_sec; > int ret, i; > u8 csra; > @@ -207,13 +225,13 @@ static int rwdt_probe(struct platform_device *pdev) > if (IS_ERR(priv->base)) > return PTR_ERR(priv->base); > > - clk = devm_clk_get(dev, NULL); > - if (IS_ERR(clk)) > - return PTR_ERR(clk); > + priv->clk = devm_clk_get(dev, NULL); > + if (IS_ERR(priv->clk)) > + return PTR_ERR(priv->clk); > > pm_runtime_enable(dev); > pm_runtime_get_sync(dev); > - priv->clk_rate = clk_get_rate(clk); > + priv->clk_rate = clk_get_rate(priv->clk); > csra = readb_relaxed(priv->base + RWTCSRA); > priv->wdev.bootstatus = csra & RWTCSRA_WOVF ? WDIOF_CARDRESET : 0; > pm_runtime_put(dev); >
On Sat, Dec 19, 2020 at 6:36 PM Wolfram Sang <wsa+renesas@sang-engineering.com> wrote: > In the restart handler, we hit multiple OOPSes. One because of > usleep_range() and one because of RPM. So, instead of re-using > rwdt_start(), we implement an atomic version of it in the restart > handler. As a little bonus, reboot will occur sooner because we can now > use the smallest divider in the custom restart routine. > > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
Hi Wolfram, Thanks for your work. On 2020-12-19 18:34:15 +0100, Wolfram Sang wrote: > In the restart handler, we hit multiple OOPSes. One because of > usleep_range() and one because of RPM. So, instead of re-using > rwdt_start(), we implement an atomic version of it in the restart > handler. As a little bonus, reboot will occur sooner because we can now > use the smallest divider in the custom restart routine. > > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se> > --- > > It is problematic to add a Fixes: tag because we would need three of > them. So, I'd think we add a stable tag and as long as the patch > applies, all is fine. Other opinions? > > drivers/watchdog/renesas_wdt.c | 30 ++++++++++++++++++++++++------ > 1 file changed, 24 insertions(+), 6 deletions(-) > > diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c > index 47fce4de0110..d2b5074bca65 100644 > --- a/drivers/watchdog/renesas_wdt.c > +++ b/drivers/watchdog/renesas_wdt.c > @@ -9,6 +9,7 @@ > #include <linux/clk.h> > #include <linux/delay.h> > #include <linux/io.h> > +#include <linux/iopoll.h> > #include <linux/kernel.h> > #include <linux/module.h> > #include <linux/of.h> > @@ -50,6 +51,7 @@ struct rwdt_priv { > struct watchdog_device wdev; > unsigned long clk_rate; > u8 cks; > + struct clk *clk; > }; > > static void rwdt_write(struct rwdt_priv *priv, u32 val, unsigned int reg) > @@ -125,13 +127,30 @@ static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev) > return DIV_BY_CLKS_PER_SEC(priv, 65536 - val); > } > > +/* needs to be atomic - no RPM, no usleep_range, no scheduling! */ > static int rwdt_restart(struct watchdog_device *wdev, unsigned long action, > void *data) > { > struct rwdt_priv *priv = watchdog_get_drvdata(wdev); > + u8 val; > + > + clk_prepare_enable(priv->clk); > + > + /* Stop the timer before we modify any register */ > + val = readb_relaxed(priv->base + RWTCSRA) & ~RWTCSRA_TME; > + rwdt_write(priv, val, RWTCSRA); > + /* Delay 2 cycles before setting watchdog counter */ > + udelay(DIV_ROUND_UP(2 * 1000000, priv->clk_rate)); > > - rwdt_start(wdev); > rwdt_write(priv, 0xffff, RWTCNT); > + /* smallest divider to reboot soon */ > + rwdt_write(priv, 0, RWTCSRA); > + > + readb_poll_timeout_atomic(priv->base + RWTCSRA, val, > + !(val & RWTCSRA_WRFLG), 1, 100); > + > + rwdt_write(priv, RWTCSRA_TME, RWTCSRA); > + > return 0; > } > > @@ -191,7 +210,6 @@ static int rwdt_probe(struct platform_device *pdev) > { > struct device *dev = &pdev->dev; > struct rwdt_priv *priv; > - struct clk *clk; > unsigned long clks_per_sec; > int ret, i; > u8 csra; > @@ -207,13 +225,13 @@ static int rwdt_probe(struct platform_device *pdev) > if (IS_ERR(priv->base)) > return PTR_ERR(priv->base); > > - clk = devm_clk_get(dev, NULL); > - if (IS_ERR(clk)) > - return PTR_ERR(clk); > + priv->clk = devm_clk_get(dev, NULL); > + if (IS_ERR(priv->clk)) > + return PTR_ERR(priv->clk); > > pm_runtime_enable(dev); > pm_runtime_get_sync(dev); > - priv->clk_rate = clk_get_rate(clk); > + priv->clk_rate = clk_get_rate(priv->clk); > csra = readb_relaxed(priv->base + RWTCSRA); > priv->wdev.bootstatus = csra & RWTCSRA_WOVF ? WDIOF_CARDRESET : 0; > pm_runtime_put(dev); > -- > 2.29.2 > -- Regards, Niklas Söderlund
diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c index 47fce4de0110..d2b5074bca65 100644 --- a/drivers/watchdog/renesas_wdt.c +++ b/drivers/watchdog/renesas_wdt.c @@ -9,6 +9,7 @@ #include <linux/clk.h> #include <linux/delay.h> #include <linux/io.h> +#include <linux/iopoll.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/of.h> @@ -50,6 +51,7 @@ struct rwdt_priv { struct watchdog_device wdev; unsigned long clk_rate; u8 cks; + struct clk *clk; }; static void rwdt_write(struct rwdt_priv *priv, u32 val, unsigned int reg) @@ -125,13 +127,30 @@ static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev) return DIV_BY_CLKS_PER_SEC(priv, 65536 - val); } +/* needs to be atomic - no RPM, no usleep_range, no scheduling! */ static int rwdt_restart(struct watchdog_device *wdev, unsigned long action, void *data) { struct rwdt_priv *priv = watchdog_get_drvdata(wdev); + u8 val; + + clk_prepare_enable(priv->clk); + + /* Stop the timer before we modify any register */ + val = readb_relaxed(priv->base + RWTCSRA) & ~RWTCSRA_TME; + rwdt_write(priv, val, RWTCSRA); + /* Delay 2 cycles before setting watchdog counter */ + udelay(DIV_ROUND_UP(2 * 1000000, priv->clk_rate)); - rwdt_start(wdev); rwdt_write(priv, 0xffff, RWTCNT); + /* smallest divider to reboot soon */ + rwdt_write(priv, 0, RWTCSRA); + + readb_poll_timeout_atomic(priv->base + RWTCSRA, val, + !(val & RWTCSRA_WRFLG), 1, 100); + + rwdt_write(priv, RWTCSRA_TME, RWTCSRA); + return 0; } @@ -191,7 +210,6 @@ static int rwdt_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; struct rwdt_priv *priv; - struct clk *clk; unsigned long clks_per_sec; int ret, i; u8 csra; @@ -207,13 +225,13 @@ static int rwdt_probe(struct platform_device *pdev) if (IS_ERR(priv->base)) return PTR_ERR(priv->base); - clk = devm_clk_get(dev, NULL); - if (IS_ERR(clk)) - return PTR_ERR(clk); + priv->clk = devm_clk_get(dev, NULL); + if (IS_ERR(priv->clk)) + return PTR_ERR(priv->clk); pm_runtime_enable(dev); pm_runtime_get_sync(dev); - priv->clk_rate = clk_get_rate(clk); + priv->clk_rate = clk_get_rate(priv->clk); csra = readb_relaxed(priv->base + RWTCSRA); priv->wdev.bootstatus = csra & RWTCSRA_WOVF ? WDIOF_CARDRESET : 0; pm_runtime_put(dev);
In the restart handler, we hit multiple OOPSes. One because of usleep_range() and one because of RPM. So, instead of re-using rwdt_start(), we implement an atomic version of it in the restart handler. As a little bonus, reboot will occur sooner because we can now use the smallest divider in the custom restart routine. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> --- It is problematic to add a Fixes: tag because we would need three of them. So, I'd think we add a stable tag and as long as the patch applies, all is fine. Other opinions? drivers/watchdog/renesas_wdt.c | 30 ++++++++++++++++++++++++------ 1 file changed, 24 insertions(+), 6 deletions(-)