[RESEND PATCH] amba: Allow pclk to be controlled by power domain

[RESEND PATCH] amba: Allow pclk to be controlled by power domain

[Bjorn Andersson]

On the Qualcomm SDM845 platform the apb_pclk is controlled as part of
the QDSS power/clock domain. Handle this by allowing amba to operate
without direct apb_pclk control, when a powerdomain is attached and no
clock is described.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---

Resending this separate from the series it was originally part of.

 drivers/amba/bus.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 41b706403ef7..3e13050c6d59 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -219,8 +219,13 @@ static int amba_get_enable_pclk(struct amba_device *pcdev)
 	int ret;
 
 	pcdev->pclk = clk_get(&pcdev->dev, "apb_pclk");
-	if (IS_ERR(pcdev->pclk))
-		return PTR_ERR(pcdev->pclk);
+	if (IS_ERR(pcdev->pclk)) {
+		/* Continue with no clock specified, but pm_domain attached */
+		if (PTR_ERR(pcdev->pclk) == -ENOENT && pcdev->dev.pm_domain)
+			pcdev->pclk = NULL;
+		else
+			return PTR_ERR(pcdev->pclk);
+	}
 
 	ret = clk_prepare_enable(pcdev->pclk);
 	if (ret)
-- 
2.18.0

Re: [RESEND PATCH] amba: Allow pclk to be controlled by power domain

[Sai Prakash Ranjan]

On 1/31/2019 7:31 AM, Bjorn Andersson wrote:
> On the Qualcomm SDM845 platform the apb_pclk is controlled as part of
> the QDSS power/clock domain. Handle this by allowing amba to operate
> without direct apb_pclk control, when a powerdomain is attached and no
> clock is described.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> ---
> 
> Resending this separate from the series it was originally part of.
> 
>   drivers/amba/bus.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index 41b706403ef7..3e13050c6d59 100644
> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -219,8 +219,13 @@ static int amba_get_enable_pclk(struct amba_device *pcdev)
>   	int ret;
>   
>   	pcdev->pclk = clk_get(&pcdev->dev, "apb_pclk");
> -	if (IS_ERR(pcdev->pclk))
> -		return PTR_ERR(pcdev->pclk);
> +	if (IS_ERR(pcdev->pclk)) {
> +		/* Continue with no clock specified, but pm_domain attached */
> +		if (PTR_ERR(pcdev->pclk) == -ENOENT && pcdev->dev.pm_domain)
> +			pcdev->pclk = NULL;
> +		else
> +			return PTR_ERR(pcdev->pclk);
> +	}
>   
>   	ret = clk_prepare_enable(pcdev->pclk);
>   	if (ret)
> 

Thanks.

Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>

-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation

Re: [RESEND PATCH] amba: Allow pclk to be controlled by power domain

[Ulf Hansson]

On Thu, 31 Jan 2019 at 03:01, Bjorn Andersson
<bjorn.andersson@linaro.org> wrote:
>
> On the Qualcomm SDM845 platform the apb_pclk is controlled as part of
> the QDSS power/clock domain. Handle this by allowing amba to operate
> without direct apb_pclk control, when a powerdomain is attached and no
> clock is described.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> ---
>
> Resending this separate from the series it was originally part of.
>
>  drivers/amba/bus.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index 41b706403ef7..3e13050c6d59 100644
> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -219,8 +219,13 @@ static int amba_get_enable_pclk(struct amba_device *pcdev)
>         int ret;
>
>         pcdev->pclk = clk_get(&pcdev->dev, "apb_pclk");
> -       if (IS_ERR(pcdev->pclk))
> -               return PTR_ERR(pcdev->pclk);
> +       if (IS_ERR(pcdev->pclk)) {
> +               /* Continue with no clock specified, but pm_domain attached */
> +               if (PTR_ERR(pcdev->pclk) == -ENOENT && pcdev->dev.pm_domain)
> +                       pcdev->pclk = NULL;

This looks fragile to me.

I would prefer to make a do match with DT, to check whether the clock
is needed or not. Moreover, there should be no reason to check for the
->dev.pm_domain, because, if there was an error while doing the
attach, that should already have been reported/propagated.

> +               else
> +                       return PTR_ERR(pcdev->pclk);
> +       }
>
>         ret = clk_prepare_enable(pcdev->pclk);
>         if (ret)
> --
> 2.18.0
>

Kind regards
Uffe

Re: [RESEND PATCH] amba: Allow pclk to be controlled by power domain

[Bjorn Andersson]

On Tue 05 Feb 06:58 PST 2019, Ulf Hansson wrote:

> On Thu, 31 Jan 2019 at 03:01, Bjorn Andersson
> <bjorn.andersson@linaro.org> wrote:
> >
> > On the Qualcomm SDM845 platform the apb_pclk is controlled as part of
> > the QDSS power/clock domain. Handle this by allowing amba to operate
> > without direct apb_pclk control, when a powerdomain is attached and no
> > clock is described.
> >
> > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> > ---
> >
> > Resending this separate from the series it was originally part of.
> >
> >  drivers/amba/bus.c | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> > index 41b706403ef7..3e13050c6d59 100644
> > --- a/drivers/amba/bus.c
> > +++ b/drivers/amba/bus.c
> > @@ -219,8 +219,13 @@ static int amba_get_enable_pclk(struct amba_device *pcdev)
> >         int ret;
> >
> >         pcdev->pclk = clk_get(&pcdev->dev, "apb_pclk");
> > -       if (IS_ERR(pcdev->pclk))
> > -               return PTR_ERR(pcdev->pclk);
> > +       if (IS_ERR(pcdev->pclk)) {
> > +               /* Continue with no clock specified, but pm_domain attached */
> > +               if (PTR_ERR(pcdev->pclk) == -ENOENT && pcdev->dev.pm_domain)
> > +                       pcdev->pclk = NULL;
> 
> This looks fragile to me.
> 
> I would prefer to make a do match with DT, to check whether the clock
> is needed or not.

Can you please elaborate on what you want me to match on?

As an example you can find the patch depending on this here:
https://lore.kernel.org/lkml/60ebf1617f0285c89e921bf3839cba6906d493c9.1548419933.git.saiprakash.ranjan@codeaurora.org/

> Moreover, there should be no reason to check for the
> ->dev.pm_domain, because, if there was an error while doing the
> attach, that should already have been reported/propagated.
> 

The purpose of this check was to extend the current requirement of a
clock to require either a clock or a power domain, rather than just
making the clock optional - which would be the result if this part is
omitted.

Regards,
Bjorn

> > +               else
> > +                       return PTR_ERR(pcdev->pclk);
> > +       }
> >
> >         ret = clk_prepare_enable(pcdev->pclk);
> >         if (ret)
> > --
> > 2.18.0
> >
> 
> Kind regards
> Uffe

Re: [RESEND PATCH] amba: Allow pclk to be controlled by power domain

[Ulf Hansson]

On Tue, 19 Feb 2019 at 07:43, Bjorn Andersson
<bjorn.andersson@linaro.org> wrote:
>
> On Tue 05 Feb 06:58 PST 2019, Ulf Hansson wrote:
>
> > On Thu, 31 Jan 2019 at 03:01, Bjorn Andersson
> > <bjorn.andersson@linaro.org> wrote:
> > >
> > > On the Qualcomm SDM845 platform the apb_pclk is controlled as part of
> > > the QDSS power/clock domain. Handle this by allowing amba to operate
> > > without direct apb_pclk control, when a powerdomain is attached and no
> > > clock is described.
> > >
> > > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> > > ---
> > >
> > > Resending this separate from the series it was originally part of.
> > >
> > >  drivers/amba/bus.c | 9 +++++++--
> > >  1 file changed, 7 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> > > index 41b706403ef7..3e13050c6d59 100644
> > > --- a/drivers/amba/bus.c
> > > +++ b/drivers/amba/bus.c
> > > @@ -219,8 +219,13 @@ static int amba_get_enable_pclk(struct amba_device *pcdev)
> > >         int ret;
> > >
> > >         pcdev->pclk = clk_get(&pcdev->dev, "apb_pclk");
> > > -       if (IS_ERR(pcdev->pclk))
> > > -               return PTR_ERR(pcdev->pclk);
> > > +       if (IS_ERR(pcdev->pclk)) {
> > > +               /* Continue with no clock specified, but pm_domain attached */
> > > +               if (PTR_ERR(pcdev->pclk) == -ENOENT && pcdev->dev.pm_domain)
> > > +                       pcdev->pclk = NULL;
> >
> > This looks fragile to me.
> >
> > I would prefer to make a do match with DT, to check whether the clock
> > is needed or not.
>
> Can you please elaborate on what you want me to match on?
>
> As an example you can find the patch depending on this here:
> https://lore.kernel.org/lkml/60ebf1617f0285c89e921bf3839cba6906d493c9.1548419933.git.saiprakash.ranjan@codeaurora.org/

I would extend the compatible with a "soc-id" prefix and match on that.

If that doesn't work, I guess we need check for the soc family/id,
thus use soc_device_match().

>
> > Moreover, there should be no reason to check for the
> > ->dev.pm_domain, because, if there was an error while doing the
> > attach, that should already have been reported/propagated.
> >
>
> The purpose of this check was to extend the current requirement of a
> clock to require either a clock or a power domain, rather than just
> making the clock optional - which would be the result if this part is
> omitted.

Well, that would break the current requirement for everybody else,
which is that the clock is required and the PM domain is optional.

[...]

Kind regards
Uffe