Re: [PATCH] i2c: rcar: disable runtime PM correctly in slave mode

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi Wolfram,

On Wed, Dec 16, 2015 at 4:43 PM, Wolfram Sang <wsa@xxxxxxxxxxxxx> wrote:
> I have another case, may I ask your advice about this, too? When an I2C
> bus is marked in DT as multi-master, then RuntimePM also needs to be
> disabled, because arbitration detection needs to stay awake. I am
> currently implementing this for the i2c-rcar driver:
>
> -       pm_runtime_enable(dev);
> +       /* No RuntimePM in multi-master to keep arbitration working */
> +       if (!of_get_property(dev->of_node, "multi-master", NULL)) {
> +               pm_runtime_enable(dev);
> +               priv->flags |= ID_P_PM;
> +       }
> +
>         pm_runtime_get_sync(dev);
>         ...
>
> @@ -664,7 +673,8 @@ static int rcar_i2c_remove(struct platform_device *pdev)
>         struct device *dev = &pdev->dev;
>
>         i2c_del_adapter(&priv->adap);
> -       pm_runtime_disable(dev);
> +       if (priv->flags & ID_P_PM)
> +               pm_runtime_disable(dev);
>
>         return 0;
>  }
>
> Here, I'd tend to keep using enable/disable, although get/put would
> probably also work. What is the rule of thumb using this pattern or the
> other?

Have you actually tried the above?

All our drivers rely on Runtime PM for the power/clock domain handling.
I believe the pm_runtime_get_sync() won't do anything if you haven't enabled
Runtime PM for the device, so the device's module clock won't be enabled at
all.

Hence I think you should add just add additional pm_runtime_get_sync()/
pm_runtime_put() calls in the driver's probe() and remove() methods if
multi-master mode is enabled.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

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
--
To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux GPIO]     [Linux SPI]     [Linux Hardward Monitoring]     [LM Sensors]     [Linux USB Devel]     [Linux Media]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux