[U-Boot] [PATCH 1/2] dm: core: device: switch off power domain after device removal

[Simon Glass]

Hi Anatolij,

On Wed, 10 Jul 2019 at 08:09, Anatolij Gustschin <agust at denx.de> wrote:
>
> The power domain associated with a device is enabled when probing,
> but currently the domain remains enabled when the device is removed.
> Some boards started to disable power domains for selected devices
> via custom board_quiesce_devices(), but it doesn't work in many
> cases, i. e. because devices still can be accessed later in
> .remove() callback on behalf of dm_remove_devices_flags().
>
> Utilize the DM core to power off the device power domain, but add a
> device flag to be able to selectively let the power domain enabled
> after device removal. This might be required for devices that must
> remain enabled when booting OS, i. e. serial console for debug
> output, etc.
>
> Signed-off-by: Anatolij Gustschin <agust at denx.de>
> ---
>  drivers/core/device-remove.c | 8 ++++++++
>  include/dm/device.h          | 6 ++++++
>  2 files changed, 14 insertions(+)
>
> diff --git a/drivers/core/device-remove.c b/drivers/core/device-remove.c
> index 586fadee0a..8675c29b6c 100644
> --- a/drivers/core/device-remove.c
> +++ b/drivers/core/device-remove.c
> @@ -16,6 +16,7 @@
>  #include <dm/uclass.h>
>  #include <dm/uclass-internal.h>
>  #include <dm/util.h>
> +#include <power-domain.h>
>
>  int device_chld_unbind(struct udevice *dev, struct driver *drv)
>  {
> @@ -154,6 +155,7 @@ static bool flags_remove(uint flags, uint drv_flags)
>
>  int device_remove(struct udevice *dev, uint flags)
>  {
> +       struct power_domain pd;
>         const struct driver *drv;
>         int ret;
>
> @@ -192,6 +194,12 @@ int device_remove(struct udevice *dev, uint flags)
>                 }
>         }
>
> +       if (dev->parent && device_get_uclass_id(dev) != UCLASS_POWER_DOMAIN &&

Putting my code-size hat on, what do you think about adding an
IF_ENABLED(POWER_DOMAIN) as the first arg?

> +           !(dev->flags & DM_FLAG_REMOVE_WITH_PD_ON)) {
> +               if (!power_domain_get(dev, &pd))
> +                       power_domain_off(&pd);
> +       }
> +
>         if (flags_remove(flags, drv->flags)) {
>                 device_free(dev);
>
> diff --git a/include/dm/device.h b/include/dm/device.h
> index 27a6d7b9fd..9a98a4a39e 100644
> --- a/include/dm/device.h
> +++ b/include/dm/device.h
> @@ -61,6 +61,12 @@ struct driver_info;
>   */
>  #define DM_FLAG_OS_PREPARE             (1 << 10)
>
> +/*
> + * Device is removed without switching off its power domain. This might
> + * be required, i. e. for serial console (debug) output when booting OS.
> + */
> +#define DM_FLAG_REMOVE_WITH_PD_ON      (1 << 11)
> +
>  /*
>   * One or multiple of these flags are passed to device_remove() so that
>   * a selective device removal as specified by the remove-stage and the
> --
> 2.17.1
>

Regards,
Simon