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Date: Wed, 22 May 2024 21:35:49 -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: [PATCH v16 08/22] PCI: microchip: Change the argument of
 plda_pcie_setup_iomems()
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On Thu, May 23, 2024 at 01:09:58AM +0000, Minda Chen wrote:
> > 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.
> > 
> OK, Thanks. 
> 
> I see PCIe 6.10 changed have been merged to main line. 
> Should I resend this patch set base on 6.10-rc1? 

No need, I rebased it to f0bae243b2bc ("Merge tag 'pci-v6.10-changes'
of git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci") already and
it will be a trivial rebase to v6.10-rc1 next week.

The current pci/controller/microchip branch is at:
https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/log/?h=ed261441e224
Let me know if anything is missing from there.  I can't merge it into
linux-next until v6.10-rc1 is tagged, but as soon as it is, I'll put
it in linux-next.

> > > > > 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
> > > > >