linux-kernel - Re: [PATCH 3/5] remoteproc: imx_rproc: Convert to dev_pm_domain_attach|detach

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Message-ID: <CAPDyKFqgw_my76dicP9wuQAmF=kF=v5wGwxEF05wTQHdSvfuCA@mail.gmail.com>
Date: Wed, 3 Jan 2024 11:11:19 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: "Rafael J . Wysocki" <rafael@...nel.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Viresh Kumar <viresh.kumar@...aro.org>, linux-pm@...r.kernel.org, 
	Sudeep Holla <sudeep.holla@....com>, Kevin Hilman <khilman@...nel.org>, 
	Konrad Dybcio <konrad.dybcio@...aro.org>, Bjorn Andersson <andersson@...nel.org>, 
	Nikunj Kela <nkela@...cinc.com>, Prasad Sodagudi <psodagud@...cinc.com>, 
	Stephan Gerhold <stephan@...hold.net>, Ben Horgan <Ben.Horgan@....com>, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-remoteproc@...r.kernel.org, 
	linux-media@...r.kernel.org, Shawn Guo <shawnguo@...nel.org>, 
	Sascha Hauer <s.hauer@...gutronix.de>
Subject: Re: [PATCH 3/5] remoteproc: imx_rproc: Convert to dev_pm_domain_attach|detach_list()

On Tue, 2 Jan 2024 at 19:41, Mathieu Poirier <mathieu.poirier@...aro.org> wrote:
>
> Hi Ulf,
>
> I'm in agreement with the modifications done to imx_rproc.c and imx_dsp_rproc.c.
> There is one thing I am ambivalent on, please see below.
>
> On Thu, Dec 28, 2023 at 12:41:55PM +0100, Ulf Hansson wrote:
> > Let's avoid the boilerplate code to manage the multiple PM domain case, by
> > converting into using dev_pm_domain_attach|detach_list().
> >
> > Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
> > Cc: Bjorn Andersson <andersson@...nel.org>
> > Cc: Shawn Guo <shawnguo@...nel.org>
> > Cc: Sascha Hauer <s.hauer@...gutronix.de>
> > Cc: <linux-remoteproc@...r.kernel.org>
> > Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
> > ---
> >  drivers/remoteproc/imx_rproc.c | 73 +++++-----------------------------
> >  1 file changed, 9 insertions(+), 64 deletions(-)
> >
> > diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
> > index 8bb293b9f327..3161f14442bc 100644
> > --- a/drivers/remoteproc/imx_rproc.c
> > +++ b/drivers/remoteproc/imx_rproc.c
> > @@ -92,7 +92,6 @@ struct imx_rproc_mem {
> >
> >  static int imx_rproc_xtr_mbox_init(struct rproc *rproc);
> >  static void imx_rproc_free_mbox(struct rproc *rproc);
> > -static int imx_rproc_detach_pd(struct rproc *rproc);
> >
> >  struct imx_rproc {
> >       struct device                   *dev;
> > @@ -113,10 +112,8 @@ struct imx_rproc {
> >       u32                             rproc_pt;       /* partition id */
> >       u32                             rsrc_id;        /* resource id */
> >       u32                             entry;          /* cpu start address */
> > -     int                             num_pd;
> >       u32                             core_index;
> > -     struct device                   **pd_dev;
> > -     struct device_link              **pd_dev_link;
> > +     struct dev_pm_domain_list       *pd_list;
> >  };
> >
> >  static const struct imx_rproc_att imx_rproc_att_imx93[] = {
> > @@ -853,7 +850,7 @@ static void imx_rproc_put_scu(struct rproc *rproc)
> >               return;
> >
> >       if (imx_sc_rm_is_resource_owned(priv->ipc_handle, priv->rsrc_id)) {
> > -             imx_rproc_detach_pd(rproc);
> > +             dev_pm_domain_detach_list(priv->pd_list);
> >               return;
> >       }
> >
> > @@ -880,72 +877,20 @@ static int imx_rproc_partition_notify(struct notifier_block *nb,
> >  static int imx_rproc_attach_pd(struct imx_rproc *priv)
> >  {
> >       struct device *dev = priv->dev;
> > -     int ret, i;
> > -
> > -     /*
> > -      * If there is only one power-domain entry, the platform driver framework
> > -      * will handle it, no need handle it in this driver.
> > -      */
> > -     priv->num_pd = of_count_phandle_with_args(dev->of_node, "power-domains",
> > -                                               "#power-domain-cells");
> > -     if (priv->num_pd <= 1)
> > -             return 0;
>
> In function dev_pm_domain_attach_list(), this condition is "<= 0" rather than
> "<= 1".  As such the association between the device and power domain will be
> done twice when there is a single power domain, i.e once by the core and once in
> dev_pm_domain_attach_list().
>
> I am assuming the runtime PM subsystem is smart enough to deal with this kind of
> situation but would like a confirmation.

Thanks for reviewing!

To cover the the single PM domain case, imx_rproc_attach_pd() is
returning 0 when dev->pm_domain has been assigned. Moreover,
dev_pm_domain_attach_list() doesn't allow attaching in the single PM
domain case, as it returns -EEXIST if "dev->pm_domain" is already
assigned.

Did that make sense to you?

[...]

Kind regards
Uffe