linux-kernel - Re: [PATCH v2 1/8] PCI: rcar-gen2: Add support for clocks

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Message-ID: <20220414154232.098a4451@bootlin.com>
Date:   Thu, 14 Apr 2022 15:42:32 +0200
From:   Herve Codina <herve.codina@...tlin.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Marek Vasut <marek.vasut+renesas@...il.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Magnus Damm <magnus.damm@...il.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Rob Herring <robh@...nel.org>,
        linux-pci <linux-pci@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Sergey Shtylyov <s.shtylyov@....ru>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Clement Leger <clement.leger@...tlin.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>
Subject: Re: [PATCH v2 1/8] PCI: rcar-gen2: Add support for clocks

Hi Geert,

On Thu, 14 Apr 2022 13:48:22 +0200
Geert Uytterhoeven <geert@...ux-m68k.org> wrote:

> Hi Hervé,
> 
> On Thu, Apr 14, 2022 at 1:29 PM Herve Codina <herve.codina@...tlin.com> wrote:
> > On Thu, 14 Apr 2022 10:45:54 +0200
> > Geert Uytterhoeven <geert@...ux-m68k.org> wrote:  
> > > On Thu, Apr 14, 2022 at 9:40 AM Herve Codina <herve.codina@...tlin.com> wrote:  
> > > > The PCI rcar-gen2 does not call any clk_prepare_enable().  
> > >
> > > Correct, this driver manages the clocks indirectly through Runtime PM.
> > >  
> > > > This lead to an access failure when the driver tries to access
> > > > the IP (at least on a RZ/N1D platform).  
> > >
> > > I expect adding
> > >
> > >     power-domans = <&sysctrl>;
> > >
> > > to the pci_usb node makes this patch redundant.  
> >
> > Seems not enough.
> > I tried what you suggest :
> >  - Added 'power-domains = <&systrl>;' to the pci_usb node
> >  - Added missing '#power-domain-cells = <0>;' to sysctrl node
> >  - Reverted my patch.
> >
> > The system crashed at boot:  
> 
> > [    0.832958] Unhandled fault: external abort on non-linefetch (0x1008) at 0x90b5f848  
> 
> That's indeed a typical symptom of accessing a module's registers
> while the module's clock is disabled.
> 
> > I also added a trace printk in r9a06g032-clocks.c and
> > r9a06g032_attach_dev() was never called.
> >
> > Did I miss to set something ?  
> 
> Do you have CONFIG_PM and CONFIG_PM_GENERIC_DOMAINS
> enabled?
> Apparently ARCH_RZN1 does not select these options yet.
> 

Thanks a lot for pointing this.

I added select CONFIG_PM and CONFIG_PM_GENERIC_DOMAINS
in ARCH_RZN1 and it works.

I will remove my patch calling clk_bulk_prepare_enable() and
add some new patches to enable power domains in the v3 series.

Regards,
Hervé