[RFC 2/2] Revert "dm: core: device: switch off power domain after device removal"

[Anatolij Gustschin]

On Thu, 13 Feb 2020 18:12:12 +0100
Neil Armstrong narmstrong at baylibre.com wrote:

> Hi,
> 
> On 03/02/2020 14:59, Oliver Graute wrote:
> > The conga-imx8 board isn't booting without this revert. Can someone tell me
> > what I need to Do so that this revert is not necessary?
> > 
> > This reverts commit 52edfed65de967a86983a55c51ba0727090efc43.
> > ---
> >  drivers/core/device-remove.c | 5 -----
> >  1 file changed, 5 deletions(-)
> > 
> > diff --git a/drivers/core/device-remove.c b/drivers/core/device-remove.c
> > index 5c8dc4ad70..586fadee0a 100644
> > --- a/drivers/core/device-remove.c
> > +++ b/drivers/core/device-remove.c
> > @@ -16,7 +16,6 @@
> >  #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)
> >  {
> > @@ -193,10 +192,6 @@ int device_remove(struct udevice *dev, uint flags)
> >  		}
> >  	}
> >  
> > -	if (!(drv->flags & DM_FLAG_DEFAULT_PD_CTRL_OFF) &&
> > -	    (dev != gd->cur_serial_dev))
> > -		dev_power_domain_off(dev);
> > -
> >  	if (flags_remove(flags, drv->flags)) {
> >  		device_free(dev);
> >  
> >   
> 
> It also breaks amlogic boards with video, since we can't tell we want
> to keep the power domains up after boot, it cuts the power domains and
> thus defeats all the goal of u-boot video...
> 
> The problem is DM_FLAG_DEFAULT_PD_CTRL_OFF disables auto power domain on
> aswell, reverting to manual power domain enable.

Yes, in some special cases manual power domain enable is required,
this is the reason why this flag has been introduced. This flag is
not for controlling power off for auto-enabled domains.

My original patch v3 [1] suggested another flag DM_FLAG_REMOVE_WITH_PD_ON,
but in the subsequent patch (which was then merged) Lokesh replaced this
with another flag DM_FLAG_DEFAULT_PD_CTRL_OFF for different purpose and
dropped DM_FLAG_REMOVE_WITH_PD_ON.

Unfortunately Lokesh copied the commit message from my patch v3 to
the updated patch without modification and so this merged commit doesn't
correctly describe the code changes. Unfortunately I didn't have
time to properly review and test this merged patch back then.

[1] https://patchwork.ozlabs.org/patch/1140138

--
Anatolij