From: Ulf Hansson <ulf.hansson@linaro.org>
To: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Russell King <linux@armlinux.org.uk>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Subject: Re: [RESEND PATCH] amba: Allow pclk to be controlled by power domain
Date: Thu, 21 Feb 2019 08:55:00 +0100 [thread overview]
Message-ID: <CAPDyKFrWZ5C=rp7_ad0Pvz-GFb20yU+BZn_hEHxR_6DDBW8zrQ@mail.gmail.com> (raw)
In-Reply-To: <20190219064342.GC13018@tuxbook-pro>
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
prev parent reply other threads:[~2019-02-21 7:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-31 2:01 [RESEND PATCH] amba: Allow pclk to be controlled by power domain Bjorn Andersson
2019-01-31 10:32 ` Sai Prakash Ranjan
2019-02-05 14:58 ` Ulf Hansson
2019-02-19 6:43 ` Bjorn Andersson
2019-02-21 7:55 ` Ulf Hansson [this message]
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