2020-01-13 09:16:42

by Marco Felsch

Subject: [PATCH] watchdog: da9062: make restart handler atomic safe

The restart handler is executed during the shutdown phase which is
atomic/irq-less. The i2c framework supports atomic transfers since
commit 63b96983a5dd ("i2c: core: introduce callbacks for atomic
transfers") but unfortunately the regmap framework doesn't support it
yet. Hard coding the i2c stuff can be done without worries since the
DA9062 is an i2c-only device.

Signed-off-by: Marco Felsch <[email protected]>
---
Hi,

This patch is based on Stefan Lengfeld's RFC Patch [1].

[1] https://patchwork.ozlabs.org/patch/1085942/
---
drivers/watchdog/da9062_wdt.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/watchdog/da9062_wdt.c b/drivers/watchdog/da9062_wdt.c
index c9b9d6394525..84c5a0a455b2 100644
--- a/drivers/watchdog/da9062_wdt.c
+++ b/drivers/watchdog/da9062_wdt.c
@@ -11,6 +11,7 @@
#include <linux/platform_device.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
+#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/mfd/da9062/registers.h>
@@ -149,12 +150,18 @@ static int da9062_wdt_restart(struct watchdog_device *wdd, unsigned long action,
void *data)
{
struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
+ struct i2c_client *client = to_i2c_client(wdt->hw->dev);
+ u8 buf[] = {DA9062AA_CONTROL_F, DA9062AA_SHUTDOWN_MASK};
+ struct i2c_msg msg = {
+ .addr = client->addr,
+ .flags = 0,
+ .len = sizeof(buf),
+ .buf = buf,
+ };
int ret;

- ret = regmap_write(wdt->hw->regmap,
- DA9062AA_CONTROL_F,
- DA9062AA_SHUTDOWN_MASK);
- if (ret)
+ ret = i2c_transfer(client->adapter, &msg, 1);
+ if (ret < 0)
dev_alert(wdt->hw->dev, "Failed to shutdown (err = %d)\n",
ret);

--
2.20.1

2020-01-13 20:29:31

by Guenter Roeck

Subject: Re: [PATCH] watchdog: da9062: make restart handler atomic safe

On Mon, Jan 13, 2020 at 10:15:21AM +0100, Marco Felsch wrote:
> The restart handler is executed during the shutdown phase which is
> atomic/irq-less. The i2c framework supports atomic transfers since
> commit 63b96983a5dd ("i2c: core: introduce callbacks for atomic
> transfers") but unfortunately the regmap framework doesn't support it
> yet. Hard coding the i2c stuff can be done without worries since the
> DA9062 is an i2c-only device.
>
> Signed-off-by: Marco Felsch <[email protected]>
> ---
> Hi,
>
> This patch is based on Stefan Lengfeld's RFC Patch [1].
>
> [1] https://patchwork.ozlabs.org/patch/1085942/
> ---
> drivers/watchdog/da9062_wdt.c | 15 +++++++++++----
> 1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/watchdog/da9062_wdt.c b/drivers/watchdog/da9062_wdt.c
> index c9b9d6394525..84c5a0a455b2 100644
> --- a/drivers/watchdog/da9062_wdt.c
> +++ b/drivers/watchdog/da9062_wdt.c
> @@ -11,6 +11,7 @@
> #include <linux/platform_device.h>
> #include <linux/uaccess.h>
> #include <linux/slab.h>
> +#include <linux/i2c.h>
> #include <linux/delay.h>
> #include <linux/jiffies.h>
> #include <linux/mfd/da9062/registers.h>
> @@ -149,12 +150,18 @@ static int da9062_wdt_restart(struct watchdog_device *wdd, unsigned long action,
> void *data)
> {
> struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
> + struct i2c_client *client = to_i2c_client(wdt->hw->dev);
> + u8 buf[] = {DA9062AA_CONTROL_F, DA9062AA_SHUTDOWN_MASK};
> + struct i2c_msg msg = {
> + .addr = client->addr,
> + .flags = 0,
> + .len = sizeof(buf),
> + .buf = buf,
> + };
> int ret;
>
> - ret = regmap_write(wdt->hw->regmap,
> - DA9062AA_CONTROL_F,
> - DA9062AA_SHUTDOWN_MASK);
> - if (ret)
> + ret = i2c_transfer(client->adapter, &msg, 1);

Why not i2c_smbus_write_byte_data() ? I don't immediately see the difference.

Guenter

> + if (ret < 0)
> dev_alert(wdt->hw->dev, "Failed to shutdown (err = %d)\n",
> ret);
>
> --
> 2.20.1
>

2020-01-14 17:32:11

by Marco Felsch

Subject: Re: [PATCH] watchdog: da9062: make restart handler atomic safe

Hi,

On 20-01-13 12:28, Guenter Roeck wrote:
> On Mon, Jan 13, 2020 at 10:15:21AM +0100, Marco Felsch wrote:
> > The restart handler is executed during the shutdown phase which is
> > atomic/irq-less. The i2c framework supports atomic transfers since
> > commit 63b96983a5dd ("i2c: core: introduce callbacks for atomic
> > transfers") but unfortunately the regmap framework doesn't support it
> > yet. Hard coding the i2c stuff can be done without worries since the
> > DA9062 is an i2c-only device.
> >
> > Signed-off-by: Marco Felsch <[email protected]>
> > ---
> > Hi,
> >
> > This patch is based on Stefan Lengfeld's RFC Patch [1].
> >
> > [1] https://patchwork.ozlabs.org/patch/1085942/
> > ---
> > drivers/watchdog/da9062_wdt.c | 15 +++++++++++----
> > 1 file changed, 11 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/watchdog/da9062_wdt.c b/drivers/watchdog/da9062_wdt.c
> > index c9b9d6394525..84c5a0a455b2 100644
> > --- a/drivers/watchdog/da9062_wdt.c
> > +++ b/drivers/watchdog/da9062_wdt.c
> > @@ -11,6 +11,7 @@
> > #include <linux/platform_device.h>
> > #include <linux/uaccess.h>
> > #include <linux/slab.h>
> > +#include <linux/i2c.h>
> > #include <linux/delay.h>
> > #include <linux/jiffies.h>
> > #include <linux/mfd/da9062/registers.h>
> > @@ -149,12 +150,18 @@ static int da9062_wdt_restart(struct watchdog_device *wdd, unsigned long action,
> > void *data)
> > {
> > struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
> > + struct i2c_client *client = to_i2c_client(wdt->hw->dev);
> > + u8 buf[] = {DA9062AA_CONTROL_F, DA9062AA_SHUTDOWN_MASK};
> > + struct i2c_msg msg = {
> > + .addr = client->addr,
> > + .flags = 0,
> > + .len = sizeof(buf),
> > + .buf = buf,
> > + };
> > int ret;
> >
> > - ret = regmap_write(wdt->hw->regmap,
> > - DA9062AA_CONTROL_F,
> > - DA9062AA_SHUTDOWN_MASK);
> > - if (ret)
> > + ret = i2c_transfer(client->adapter, &msg, 1);
>
> Why not i2c_smbus_write_byte_data() ? I don't immediately see the difference.

Because I didn't noticed it, sorry. I changed it and notice no
differences. Thanks for the review =)

Regards,
Marco

> Guenter
>
> > + if (ret < 0)
> > dev_alert(wdt->hw->dev, "Failed to shutdown (err = %d)\n",
> > ret);
> >
> > --
> > 2.20.1
> >

2020-01-14 20:22:19

by Stefan Lengfeld

Subject: Re: [PATCH] watchdog: da9062: make restart handler atomic safe

Hi Marco,

On Mon, Jan 13, 2020 at 10:15:21AM +0100, Marco Felsch wrote:
> The restart handler is executed during the shutdown phase which is
> atomic/irq-less. The i2c framework supports atomic transfers since
> commit 63b96983a5dd ("i2c: core: introduce callbacks for atomic
> transfers") but unfortunately the regmap framework doesn't support it
> yet. Hard coding the i2c stuff can be done without worries since the
> DA9062 is an i2c-only device.
>
> Signed-off-by: Marco Felsch <[email protected]>

Reviewed-by: Stefan Lengfeld <[email protected]>

Thanks for picking up the patch and submitting it.

Kind regards,
Stefan

2020-01-15 07:21:39

by Marco Felsch

Subject: Re: [PATCH] watchdog: da9062: make restart handler atomic safe

Hi Stefan,

On 20-01-14 21:00, Stefan Lengfeld wrote:
> Hi Marco,
>
> On Mon, Jan 13, 2020 at 10:15:21AM +0100, Marco Felsch wrote:
> > The restart handler is executed during the shutdown phase which is
> > atomic/irq-less. The i2c framework supports atomic transfers since
> > commit 63b96983a5dd ("i2c: core: introduce callbacks for atomic
> > transfers") but unfortunately the regmap framework doesn't support it
> > yet. Hard coding the i2c stuff can be done without worries since the
> > DA9062 is an i2c-only device.
> >
> > Signed-off-by: Marco Felsch <[email protected]>
>
> Reviewed-by: Stefan Lengfeld <[email protected]>
>
> Thanks for picking up the patch and submitting it.

I will send a v2 to cover Guenter's suggestion. Can I keep your reviewed
by tag?

Regards,
Marco

> Kind regards,
> Stefan