Re: [RFC PATCH 2/3] watchdog: da9062: avoid regmap in restart handler

[Andy Shevchenko]

On Sun, Oct 07, 2018 at 05:39:36PM +0200, Stefan Lengfeld wrote:
> Using i2c_transfer() directly to set the shutdown bit is more reliable
> than using regmap in atomic contexts, because calls to 'schedule()' or
> 'sleep()' must be avoided in call code paths.

>  #include 
>  #include 
>  #include 
> +#include 
>  #include 
>  #include 
>  #include 

The rule of thumb when extending a header inclusion block is that try to
squeeze the new inclusion in the longest sorted part of the list.

Rationale behind is easy maintenance.

-- 
With Best Regards,
Andy Shevchenko

[RFC PATCH 2/3] watchdog: da9062: avoid regmap in restart handler

[Stefan Lengfeld]

Using i2c_transfer() directly to set the shutdown bit is more reliable
than using regmap in atomic contexts, because calls to 'schedule()' or
'sleep()' must be avoided in call code paths.

Tested on a phyCORE-i.MX6 Solo board.

Signed-off-by: Stefan Lengfeld 
---
 drivers/mfd/da9062-core.c   |  1 +
 drivers/watchdog/da9062_wdt.c   | 17 +
 include/linux/mfd/da9062/core.h |  1 +
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/mfd/da9062-core.c b/drivers/mfd/da9062-core.c
index 9f6105906c09..b6a01054ba0f 100644
--- a/drivers/mfd/da9062-core.c
+++ b/drivers/mfd/da9062-core.c
@@ -609,6 +609,7 @@ static int da9062_i2c_probe(struct i2c_client *i2c,
 
i2c_set_clientdata(i2c, chip);
chip->dev = &i2c->dev;
+   chip->i2c = i2c;
 
if (!i2c->irq) {
dev_err(chip->dev, "No IRQ configured\n");
diff --git a/drivers/watchdog/da9062_wdt.c b/drivers/watchdog/da9062_wdt.c
index fe169d8e1fb2..ad6483d25f83 100644
--- a/drivers/watchdog/da9062_wdt.c
+++ b/drivers/watchdog/da9062_wdt.c
@@ -11,6 +11,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -152,12 +153,20 @@ 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 = wdt->hw->i2c;
+   __u8 buf[3] = {DA9062AA_CONTROL_F, DA9062AA_SHUTDOWN_MASK, 0x0};
+   struct i2c_msg msgs[1] = {
+   {
+   .addr = client->addr,
+   .flags = (client->flags & I2C_M_TEN),
+   .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, msgs, sizeof(msgs));
+   if (ret < 0)
dev_alert(wdt->hw->dev, "Failed to shutdown (err = %d)\n",
  ret);
 
diff --git a/include/linux/mfd/da9062/core.h b/include/linux/mfd/da9062/core.h
index 74d33a01ddae..c994293b3aef 100644
--- a/include/linux/mfd/da9062/core.h
+++ b/include/linux/mfd/da9062/core.h
@@ -68,6 +68,7 @@ enum da9062_irqs {
 struct da9062 {
struct device *dev;
struct regmap *regmap;
+   struct i2c_client *i2c;
struct regmap_irq_chip_data *regmap_irq;
enum da9062_compatible_types chip_type;
 };
-- 
2.16.4