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

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

[Anatolij Gustschin]

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@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 &&
+	    !(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

[U-Boot] [PATCH 2/2] serial: lpuart: request dm device removal when booting OS

[Anatolij Gustschin]

Extend the driver to allow dm device removal, but always let the
console serial device power domain enabled, so that U-Boot doesn't
crash when i. e. the serial output is enabled for debugging.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
---
 drivers/serial/serial_lpuart.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/serial/serial_lpuart.c b/drivers/serial/serial_lpuart.c
index a357b00d28..9b56dfb11e 100644
--- a/drivers/serial/serial_lpuart.c
+++ b/drivers/serial/serial_lpuart.c
@@ -488,6 +488,13 @@ static int lpuart_serial_probe(struct udevice *dev)
 		return _lpuart_serial_init(dev);
 }
 
+static int lpuart_serial_remove(struct udevice *dev)
+{
+	if (dev == gd->cur_serial_dev)
+		dev->flags |= DM_FLAG_REMOVE_WITH_PD_ON;
+	return 0;
+}
+
 static int lpuart_serial_ofdata_to_platdata(struct udevice *dev)
 {
 	struct lpuart_serial_platdata *plat = dev->platdata;
@@ -539,5 +546,7 @@ U_BOOT_DRIVER(serial_lpuart) = {
 	.ofdata_to_platdata = lpuart_serial_ofdata_to_platdata,
 	.platdata_auto_alloc_size = sizeof(struct lpuart_serial_platdata),
 	.probe = lpuart_serial_probe,
+	.remove = lpuart_serial_remove,
 	.ops	= &lpuart_serial_ops,
+	.flags	= DM_FLAG_OS_PREPARE,
 };
-- 
2.17.1

[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@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@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

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

[Anatolij Gustschin]

Hi Simon,

On Fri, 12 Jul 2019 15:05:06 -0600
Simon Glass sjg at chromium.org wrote:
...
> >
> > +       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?

Good point, I'll add it in v2 patch.

Thanks,
Anatolij