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Date: Wed, 22 May 2024 17:10:34 -0500
From: Bjorn Helgaas <helgaas@kernel.org>
To: Minda Chen <minda.chen@starfivetech.com>
Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>,
	Conor Dooley <conor@kernel.org>,
	Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
	Rob Herring <robh+dt@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Daire McNamara <daire.mcnamara@microchip.com>,
	Emil Renner Berthing <emil.renner.berthing@canonical.com>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	Mason Huo <mason.huo@starfivetech.com>,
	Leyfoon Tan <leyfoon.tan@starfivetech.com>,
	Kevin Xie <kevin.xie@starfivetech.com>
Subject: Re: =?utf-8?B?5Zue5aSNOiBbUEFUQ0ggdjE2IDA4?=
 =?utf-8?Q?=2F22=5D_PCI?= =?utf-8?Q?=3A?= microchip: Change the argument of
 plda_pcie_setup_iomems()
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On Wed, May 22, 2024 at 01:50:57AM +0000, Minda Chen wrote:
> > The patch is OK, but the subject line is not very informative.  It
> > should be useful all by itself even without the commit log.
> > "Change the argument of X" doesn't say anything about why we would
> > want to do that.
> > 
> > On Thu, Mar 28, 2024 at 05:18:21PM +0800, Minda Chen wrote:
> > > If other vendor do not select PCI_HOST_COMMON, the driver data is not
> > > struct pci_host_bridge.
> > 
> > Also, I don't think this is the real problem.  Your PCIE_MICROCHIP_HOST
> > Kconfig selects PCI_HOST_COMMON, and the driver calls
> > pci_host_common_probe(), so the driver wouldn't even build without
> > PCI_HOST_COMMON.
> > 
> > This patch is already applied and ready to go, but if you can tell
> > us what's really going on here, I'd like to update the commit log.
> > 
> It is modified for Starfive code. Starfive JH7110 PCIe do not select
> PCI_HOST_COMMON
> plda_pcie_setup_iomems() will be changed to common plda code.
> 
> I think I can modify the title and commit log like this.
> 
> Title: 
> PCI: microchip: Get struct pci_host_bridge pointer from platform code
> 
> Since plda_pcie_setup_iomems() will be a common PLDA core driver
> function, but the argument0 is a struct platform_device pointer.
> plda_pcie_setup_iomems() actually using struct pci_host_bridge
> pointer other than platform_device pointer. Further more if a new
> PLDA core PCIe driver do not select PCI_HOST_COMMON, the platform
> driver data is not struct pci_host_bridge pointer. So get struct
> pci_host_bridge pointer from platform code function
> mc_platform_init() and make it to be an argument of
> plda_pcie_setup_iomems().

OK, I see what you're doing.  This actually has nothing to do with
whether PCI_HOST_COMMON is *enabled*.  It has to do with whether
drivers use pci_host_common_probe().  Here's what I propose:

  PCI: plda: Pass pci_host_bridge to plda_pcie_setup_iomems()

  plda_pcie_setup_iomems() needs the bridge->windows list from struct
  pci_host_bridge and is currently used only by pcie-microchip-host.c.  This
  driver uses pci_host_common_probe(), which sets a pci_host_bridge as the
  drvdata, so plda_pcie_setup_iomems() used platform_get_drvdata() to find
  the pci_host_bridge.

  But we also want to use plda_pcie_setup_iomems() in the new pcie-starfive.c
  driver, which does not use pci_host_common_probe() and will have struct
  starfive_jh7110_pcie as its drvdata, so pass the pci_host_bridge directly
  to plda_pcie_setup_iomems() so it doesn't need platform_get_drvdata() to
  find it.

> > > Move calling platform_get_drvdata() to mc_platform_init().
> > >
> > > Signed-off-by: Minda Chen <minda.chen@starfivetech.com>
> > > Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
> > > ---
> > >  drivers/pci/controller/plda/pcie-microchip-host.c | 6 +++---
> > >  1 file changed, 3 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/pci/controller/plda/pcie-microchip-host.c
> > > b/drivers/pci/controller/plda/pcie-microchip-host.c
> > > index 9b367927cd32..805870aed61d 100644
> > > --- a/drivers/pci/controller/plda/pcie-microchip-host.c
> > > +++ b/drivers/pci/controller/plda/pcie-microchip-host.c
> > > @@ -876,11 +876,10 @@ static void plda_pcie_setup_window(void __iomem
> > *bridge_base_addr, u32 index,
> > >  	writel(0, bridge_base_addr + ATR0_PCIE_WIN0_SRC_ADDR);  }
> > >
> > > -static int plda_pcie_setup_iomems(struct platform_device *pdev,
> > > +static int plda_pcie_setup_iomems(struct pci_host_bridge *bridge,
> > >  				  struct plda_pcie_rp *port)
> > >  {
> > >  	void __iomem *bridge_base_addr = port->bridge_addr;
> > > -	struct pci_host_bridge *bridge = platform_get_drvdata(pdev);
> > >  	struct resource_entry *entry;
> > >  	u64 pci_addr;
> > >  	u32 index = 1;
> > > @@ -1018,6 +1017,7 @@ static int mc_platform_init(struct
> > > pci_config_window *cfg)  {
> > >  	struct device *dev = cfg->parent;
> > >  	struct platform_device *pdev = to_platform_device(dev);
> > > +	struct pci_host_bridge *bridge = platform_get_drvdata(pdev);
> > >  	void __iomem *bridge_base_addr =
> > >  		port->axi_base_addr + MC_PCIE_BRIDGE_ADDR;
> > >  	int ret;
> > > @@ -1031,7 +1031,7 @@ static int mc_platform_init(struct
> > pci_config_window *cfg)
> > >  	mc_pcie_enable_msi(port, cfg->win);
> > >
> > >  	/* Configure non-config space outbound ranges */
> > > -	ret = plda_pcie_setup_iomems(pdev, &port->plda);
> > > +	ret = plda_pcie_setup_iomems(bridge, &port->plda);
> > >  	if (ret)
> > >  		return ret;
> > >
> > > --
> > > 2.17.1
> > >