Re: [PATCH] rpmsg: core: add support to power domains for devices

[Srinivas Kandagatla]

Hi Suman,

On 25/09/18 01:25, Suman Anna wrote:
> Hi Srinivas,
>
> On 06/15/2018 04:59 AM, Srinivas Kandagatla wrote:
> > Some of the rpmsg devices need to switch on power domains to communicate
> > with remote processor. For example on Qualcomm DB820c platform LPASS
> > power domain needs to switched on for any kind of audio services.
> > This patch adds the missing power domain support in rpmsg core.
> >
> > Without this patch attempting to play audio via QDSP on DB820c would
> > reboot the system.
> >
> > Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
> > ---
> >   drivers/rpmsg/rpmsg_core.c | 7 +++++++
> >   1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> > index b714a543a91d..8122807db380 100644
> > --- a/drivers/rpmsg/rpmsg_core.c
> > +++ b/drivers/rpmsg/rpmsg_core.c
> > @@ -15,6 +15,7 @@
> >   #include <linux/module.h>
> >   #include <linux/rpmsg.h>
> >   #include <linux/of_device.h>
> > +#include <linux/pm_domain.h>
> >   #include <linux/slab.h>
> >   
> >   #include "rpmsg_internal.h"
> > @@ -449,6 +450,10 @@ static int rpmsg_dev_probe(struct device *dev)
> >   	struct rpmsg_endpoint *ept = NULL;
> >   	int err;
> >   
> > +	err = dev_pm_domain_attach(dev, true);
> > +	if (err)
> > +		goto out;
>
> This patch has broken the virtio-rpmsg stack based rpmsg devices. These
> devices are non-DT and the rpmsg_dev_probe() is now failing with -19
> (-ENODEV) error code.

There seems to be some dependency on this patch ( 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v4.19-rc5&id=919b7308fcc452cd4e282bab389c33384a9f3790 
) which seems to rework the return values from acpi_dev_pm_attach() and 
genpd_dev_pm_attach()



--srini


> Loic, Arnaud,
> Can one of you double-confirm this behavior on ST platforms as well?
> The patch came through 4.14.71 stable release and broke our downstream
> kernels.
>
> regards
> Suman
>
> > +
> >   	if (rpdrv->callback) {
> >   		strncpy(chinfo.name, rpdev->id.name, RPMSG_NAME_SIZE);
> >   		chinfo.src = rpdev->src;
> > @@ -490,6 +495,8 @@ static int rpmsg_dev_remove(struct device *dev)
> >   
> >   	rpdrv->remove(rpdev);
> >   
> > +	dev_pm_domain_detach(dev, true);
> > +
> >   	if (rpdev->ept)
> >   		rpmsg_destroy_ept(rpdev->ept);
> >