linux-kernel - Re: [PATCH v12 05/13] PCI: dwc: Add dw_pcie_parent_bus

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Message-ID: <j3qw4zmopulpn3iqq5wsjt6dbs4z3micoeoxkw3354txkx22ml@67ip5sfo6wwd>
Date: Mon, 24 Mar 2025 22:48:23 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: Frank Li <Frank.Li@....com>, Rob Herring <robh@...nel.org>, 
	Saravana Kannan <saravanak@...gle.com>, Jingoo Han <jingoohan1@...il.com>, 
	Lorenzo Pieralisi <lpieralisi@...nel.org>, Krzysztof Wilczyński <kw@...ux.com>, 
	Richard Zhu <hongxing.zhu@....com>, Lucas Stach <l.stach@...gutronix.de>, 
	Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, 
	Fabio Estevam <festevam@...il.com>, Niklas Cassel <cassel@...nel.org>, 
	Pengutronix Kernel Team <kernel@...gutronix.de>, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, imx@...ts.linux.dev, 
	Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH v12 05/13] PCI: dwc: Add dw_pcie_parent_bus_offset()

On Sat, Mar 15, 2025 at 03:15:40PM -0500, Bjorn Helgaas wrote:
> From: Frank Li <Frank.Li@....com>
> 
> Return the offset from CPU physical address to the parent bus address of
> the specified element of the devicetree 'reg' property.
> 
> [bhelgaas: return offset, split .cpu_addr_fixup() checking and debug to
> separate patch]
> Link: https://lore.kernel.org/r/20250313-pci_fixup_addr-v11-5-01d2313502ab@nxp.com
> Signed-off-by: Frank Li <Frank.Li@....com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware.c | 23 ++++++++++++++++++++
>  drivers/pci/controller/dwc/pcie-designware.h |  3 +++
>  2 files changed, 26 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index 9d0a5f75effc..0a35e36da703 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -16,6 +16,7 @@
>  #include <linux/gpio/consumer.h>
>  #include <linux/ioport.h>
>  #include <linux/of.h>
> +#include <linux/of_address.h>
>  #include <linux/platform_device.h>
>  #include <linux/sizes.h>
>  #include <linux/types.h>
> @@ -1105,3 +1106,25 @@ void dw_pcie_setup(struct dw_pcie *pci)
>  
>  	dw_pcie_link_set_max_link_width(pci, pci->num_lanes);
>  }
> +
> +resource_size_t dw_pcie_parent_bus_offset(struct dw_pcie *pci,
> +					  const char *reg_name,
> +					  resource_size_t cpu_phy_addr)
> +{

s/cpu_phy_addr/cpu_phys_addr/g

'phy' usually refers to the physical layer IP block. So 'cpu_phy_addr' sounds
like the address of the CPU PHY.

> +	struct device *dev = pci->dev;
> +	struct device_node *np = dev->of_node;
> +	int index;
> +	u64 reg_addr;
> +
> +	/* Look up reg_name address on parent bus */

'parent bus' is not accurate as the below code checks for the 'reg_name' in
current PCI controller node.

> +	index = of_property_match_string(np, "reg-names", reg_name);
> +
> +	if (index < 0) {
> +		dev_err(dev, "No %s in devicetree \"reg\" property\n", reg_name);

Both of these callers are checking for the existence of the 'reg_name' property
before calling this API. So this check seems to be redundant (for now).

- Mani

-- 
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