Re: [PATCH V9 2/3] watchdog: s3c2410_wdt: use syscon regmap interface to configure pmu register

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Hi Leela Krishna,

On Mon, Nov 18, 2013 at 1:49 AM, Leela Krishna Amudala
<l.krishna@xxxxxxxxxxx> wrote:
> Add device tree support for exynos5250 and 5420 SoCs and use syscon regmap interface
> to configure AUTOMATIC_WDT_RESET_DISABLE and MASK_WDT_RESET_REQUEST registers of PMU
> to mask/unmask enable/disable of watchdog in probe and s2r scenarios.
>
> Signed-off-by: Leela Krishna Amudala <l.krishna@xxxxxxxxxxx>
> ---
>  .../devicetree/bindings/watchdog/samsung-wdt.txt   |   21 ++-
>  drivers/watchdog/Kconfig                           |    1 +
>  drivers/watchdog/s3c2410_wdt.c                     |  145 ++++++++++++++++++--
>  3 files changed, 157 insertions(+), 10 deletions(-)

...

> +struct s3c2410_wdt_variant {
> +       int disable_reg;
> +       int mask_reset_reg;
> +       int mask_bit;
> +       u32 quirks;
> +};

Ideally you could add descriptions.  I added them in a patch based on
yours <https://chromium-review.googlesource.com/#/c/177935/1/drivers/watchdog/s3c2410_wdt.c>,
but since yours hasn't landed perhaps you can do it directly?

/**
 * struct s3c2410_wdt_variant - Per-variant config data
 *
 * @disable_reg: Offset in pmureg for the register that disables the watchdog
 * timer reset functionality.
 * @mask_reset_reg: Offset in pmureg for the register that masks the watchdog
 * timer reset functionality.
 * @mask_bit: Bit number for the watchdog timer in the disable register and the
 * mask reset register.
 * @quirks: A bitfield of quirks.
 */

> +
>  struct s3c2410_wdt {
>         struct device           *dev;
>         struct clk              *clock;
> @@ -94,7 +107,49 @@ struct s3c2410_wdt {
>         unsigned long           wtdat_save;
>         struct watchdog_device  wdt_device;
>         struct notifier_block   freq_transition;
> +       struct s3c2410_wdt_variant *drv_data;
> +       struct regmap *pmureg;

Total nit, but everything else in this structure is tab aligned and
your new elements are not.

>  static int s3c2410wdt_probe(struct platform_device *pdev)
>  {
>         struct device *dev;
> @@ -354,6 +443,16 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>         spin_lock_init(&wdt->lock);
>         wdt->wdt_device = s3c2410_wdd;
>
> +       wdt->drv_data = get_wdt_drv_data(pdev);
> +       if (wdt->drv_data->quirks & QUIRK_NEEDS_PMU_CONFIG) {
> +               wdt->pmureg = syscon_regmap_lookup_by_phandle(dev->of_node,
> +                                                       "samsung,syscon-phandle");
> +               if (IS_ERR(wdt->pmureg)) {
> +                       dev_err(dev, "syscon regmap lookup failed.\n");
> +                       return PTR_ERR(wdt->pmureg);

nit: this function appears to never call "return" directly.  You'll
match other error handling better if you do:

ret = PTR_ERR(wdt->pmureg);
goto err;

(if someone else has already said they don't like that, just ignore me).

> +               }
> +       }
> +
>         wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
>         if (wdt_irq == NULL) {
>                 dev_err(dev, "no irq resource specified\n");
> @@ -444,6 +543,14 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>                  (wtcon & S3C2410_WTCON_RSTEN) ? "en" : "dis",
>                  (wtcon & S3C2410_WTCON_INTEN) ? "en" : "dis");
>
> +       if (wdt->drv_data->quirks & QUIRK_NEEDS_PMU_CONFIG) {
> +               ret = s3c2410wdt_mask_and_disable_reset(wdt, false);
> +               if (ret < 0) {
> +                       dev_err(wdt->dev, "failed to update pmu register");
> +                       goto err_cpufreq;
> +               }
> +       }

There are a few minor problems here:

1. You're putting a potential failure condition _after_ printing that
the watchdog is enabled.  You should put your code above the
"dev_info".

2. Error handling doesn't seem quite right.  If you fail here you'll
be returning an error but you might have started the watchdog already.
 Perhaps you should be moving the "mask_and_disable" up a little and
then you an undo it if needed?

3. I think it would be fine to put the "dev_err" directly in the
s3c2410wdt_mask_and_disable_reset() as per Guenter, but still return
the error code.  You'll still use the error code here, right?

> +
>         return 0;
>
>   err_cpufreq:
> @@ -459,8 +566,15 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>
>  static int s3c2410wdt_remove(struct platform_device *dev)
>  {
> +       int ret;
>         struct s3c2410_wdt *wdt = platform_get_drvdata(dev);
>
> +       if (wdt->drv_data->quirks & QUIRK_NEEDS_PMU_CONFIG) {
> +               ret = s3c2410wdt_mask_and_disable_reset(wdt, true);

This function does return an error.  Why not pass the error on
through?  The system wouldn't be in such a stellar state, but if
regmap is failing it's probably pretty bad anyway...



Nothing here is terrible and I wouldn't be upset if you landed these
as-is, but since it seems that Guenter is requesting a spin.  Perhaps
you could address my comments, too?


-Doug
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