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From: Chuanjia Liu <chuanjia.liu@mediatek.com>
To: Rob Herring <robh+dt@kernel.org>
Cc: Bjorn Helgaas <helgaas@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Ryder Lee <ryder.lee@mediatek.com>,
	"Jianjun Wang" <jianjun.wang@mediatek.com>,
	Yong Wu <yong.wu@mediatek.com>, PCI <linux-pci@vger.kernel.org>,
	"moderated list:ARM/Mediatek SoC support" 
	<linux-mediatek@lists.infradead.org>,
	<devicetree@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v12 2/6] PCI: mediatek: Add new method to get shared pcie-cfg base address
Date: Thu, 2 Sep 2021 17:34:08 +0800	[thread overview]
Message-ID: <eb855d186d572e8a0343456bb5d76797f8f3870f.camel@mediatek.com> (raw)
In-Reply-To: <CAL_Jsq+dBi-XUDJD_STP=jWw+RLkRpX1U9XsRMhqK4U1H=0FHw@mail.gmail.com>

On Tue, 2021-08-31 at 10:17 -0500, Rob Herring wrote:
> On Mon, Aug 30, 2021 at 10:31 PM Chuanjia Liu <
> chuanjia.liu@mediatek.com> wrote:
> > 
> > On Mon, 2021-08-30 at 16:43 -0500, Bjorn Helgaas wrote:
> > > On Mon, Aug 30, 2021 at 03:09:44PM +0800, Chuanjia Liu wrote:
> > > > On Fri, 2021-08-27 at 11:46 -0500, Bjorn Helgaas wrote:
> > > > > On Mon, Aug 23, 2021 at 11:27:56AM +0800, Chuanjia Liu wrote:
> > > > > > @@ -995,6 +1004,14 @@ static int
> > > > > > mtk_pcie_subsys_powerup(struct
> > > > > > mtk_pcie *pcie)
> > > > > >                         return PTR_ERR(pcie->base);
> > > > > >         }
> > > > > > 
> > > > > > +       cfg_node = of_find_compatible_node(NULL, NULL,
> > > > > > +                                          "mediatek,generi
> > > > > > c-
> > > > > > pciecfg");
> > > > > > +       if (cfg_node) {
> > > > > > +               pcie->cfg =
> > > > > > syscon_node_to_regmap(cfg_node);
> > > > > 
> > > > > Other drivers in drivers/pci/controller/ use
> > > > > syscon_regmap_lookup_by_phandle() (j721e, dra7xx, keystone,
> > > > > layerscape, artpec6) or syscon_regmap_lookup_by_compatible()
> > > > > (imx6,
> > > > > kirin, v3-semi).
> > > > > 
> > > > > You should do it the same way unless there's a need to be
> > > > > different.
> > > > 
> > > > I have used phandle, but Rob suggested to search for the node
> > > > by
> > > > compatible.
> > > > The reason why syscon_regmap_lookup_by_compatible() is not
> > > > used here is that the pciecfg node is optional, and there is no
> > > > need to
> > > > return error when the node is not searched.
> > > 
> > > How about this?
> > > 
> > >   regmap = syscon_regmap_lookup_by_compatible("mediatek,generic-
> > > pciecfg");
> > >   if (!IS_ERR(regmap))
> > >     pcie->cfg = regmap;
> 
> +1
> 
> > 
> > Hi Bjorn,
> > 
> > We need to deal with three situations
> > 1) No error
> > 2) The error of the node not found, don't do anything
> > 3) Other errors, return errors
> > 
> > I guess you mean
> > 
> > regmap = syscon_regmap_lookup_by_compatible("mediatek,generic-
> > pciecfg");
> >   if (!IS_ERR(regmap))
> >       pcie->cfg = regmap;
> >   else if (IS_ERR(regmap) && PTR_ERR(regmap) != -ENODEV)
> 
> You already know  IS_ERR is true here.
> 
> >       return PTR_ERR(regmap);
> 
> syscon_regmap_lookup_by_compatible_optional is the function you are
> looking for. The _optional flavor doesn't exist, so create it. There
> is one for the phandle lookup.
> 
> > 
> > I'm not sure if we need this, it seems a little weird and there are
> > many drivers in other subsystems that use syscon_node_to_regmap().
> 
> You are implementing the exact same sequence that
> syscon_regmap_lookup_by_compatible() does, so clearly you should be
> using it. The one difference is you forgot the of_node_put().

Hi,Rob
Thanks for your explanation. You're right. 
Now I understand use syscon_regmap_lookup_by_compatible() is a better
way. I'll follow your advice
 
regmap = syscon_regmap_lookup_by_compatible("mediatek,generic-
pciecfg");
if (!IS_ERR(regmap))
	pcie->cfg = regmap;
else if (PTR_ERR(regmap) != -ENODEV)
	return PTR_ERR(regmap);

Best regards
Chuanjia
 
> 
> Rob
> 
> _______________________________________________
> Linux-mediatek mailing list
> Linux-mediatek@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-mediatek

  reply	other threads:[~2021-09-02  9:34 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-23  3:27 [PATCH v12 0/6] PCI: mediatek: Spilt PCIe node to comply with hardware design Chuanjia Liu
2021-08-23  3:27 ` [PATCH v12 1/6] dt-bindings: PCI: mediatek: Update the Device tree bindings Chuanjia Liu
2021-08-23  3:27 ` [PATCH v12 2/6] PCI: mediatek: Add new method to get shared pcie-cfg base address Chuanjia Liu
2021-08-27 16:46   ` Bjorn Helgaas
2021-08-30  7:09     ` Chuanjia Liu
2021-08-30 21:43       ` Bjorn Helgaas
2021-08-31  3:31         ` Chuanjia Liu
2021-08-31 15:17           ` Rob Herring
2021-09-02  9:34             ` Chuanjia Liu [this message]
2021-08-31 15:04     ` Rob Herring
2021-08-31 15:47       ` Bjorn Helgaas
2021-08-31 18:24         ` Rob Herring
2021-08-23  3:27 ` [PATCH v12 3/6] PCI: mediatek: Add new method to get irq number Chuanjia Liu
2021-08-31 18:30   ` Bjorn Helgaas
2021-09-02  9:28     ` Chuanjia Liu
2021-08-23  3:27 ` [PATCH v12 4/6] PCI: mediatek: Get pci domain and decide how to parse node Chuanjia Liu
2021-08-23  3:27 ` [PATCH v12 5/6] arm64: dts: mediatek: Split PCIe node for MT2712 and MT7622 Chuanjia Liu
2021-09-21 18:43   ` Matthias Brugger
2021-08-23  3:28 ` [PATCH v12 6/6] ARM: dts: mediatek: Update MT7629 PCIe node for new format Chuanjia Liu
2021-09-21 18:43   ` Matthias Brugger
2021-08-26 12:53 ` [PATCH v12 0/6] PCI: mediatek: Spilt PCIe node to comply with hardware design Lorenzo Pieralisi

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