linux-kernel - Re: [PATCH RESEND 3/3] PCI: meson: Fix parsing the DBI register region

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Message-ID: <807e9f74-79ed-44bc-8a80-3d99787edc65@linaro.org>
Date: Mon, 3 Nov 2025 10:49:04 +0100
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>,
 Bjorn Helgaas <bhelgaas@...gle.com>,
 Lorenzo Pieralisi <lpieralisi@...nel.org>,
 Krzysztof Wilczyński <kwilczynski@...nel.org>,
 Manivannan Sadhasivam <mani@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Hanjie Lin <hanjie.lin@...ogic.com>,
 Yue Wang <yue.wang@...ogic.com>, Kevin Hilman <khilman@...libre.com>,
 Jerome Brunet <jbrunet@...libre.com>,
 Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
 Andrew Murray <amurray@...goodpenguin.co.uk>,
 Jingoo Han <jingoohan1@...il.com>,
 Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Cc: linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-amlogic@...ts.infradead.org, stable@...r.kernel.org,
 Linnaea Lavia <linnaea-von-lavia@...e.com>
Subject: Re: [PATCH RESEND 3/3] PCI: meson: Fix parsing the DBI register
 region

On 11/1/25 05:29, Manivannan Sadhasivam wrote:
> First of all, the driver was parsing the 'dbi' register region as 'elbi'.
> This was due to DT mistakenly passing 'dbi' as 'elbi'. Since the DT is
> now fixed to supply 'dbi' region, this driver can rely on the DWC core
> driver to parse and map it.
> 
> However, to support the old DTs, if the 'elbi' region is found in DT, parse
> and map the region as both 'dw_pcie::elbi_base' as 'dw_pcie::dbi_base'.
> This will allow the driver to work with both broken and fixed DTs.
> 
> Also, skip parsing the 'elbi' region in DWC core if 'pci->elbi_base' was
> already populated.
> 
> Cc: <stable@...r.kernel.org> # 6.2
> Reported-by: Linnaea Lavia <linnaea-von-lavia@...e.com>
> Closes: https://lore.kernel.org/linux-pci/DM4PR05MB102707B8CDF84D776C39F22F2C7F0A@DM4PR05MB10270.namprd05.prod.outlook.com/
> Fixes: 9c0ef6d34fdb ("PCI: amlogic: Add the Amlogic Meson PCIe controller driver")
> Fixes: c96992a24bec ("PCI: dwc: Add support for ELBI resource mapping")
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> ---
>   drivers/pci/controller/dwc/pci-meson.c       | 18 +++++++++++++++---
>   drivers/pci/controller/dwc/pcie-designware.c | 12 +++++++-----
>   2 files changed, 22 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-meson.c b/drivers/pci/controller/dwc/pci-meson.c
> index 787469d1b396d4c7b3e28edfe276b7b997fb8aee..54b6a4196f1767a3c14c6c901bfee3505588134c 100644
> --- a/drivers/pci/controller/dwc/pci-meson.c
> +++ b/drivers/pci/controller/dwc/pci-meson.c
> @@ -108,10 +108,22 @@ static int meson_pcie_get_mems(struct platform_device *pdev,
>   			       struct meson_pcie *mp)
>   {
>   	struct dw_pcie *pci = &mp->pci;
> +	struct resource *res;
>   
> -	pci->dbi_base = devm_platform_ioremap_resource_byname(pdev, "elbi");
> -	if (IS_ERR(pci->dbi_base))
> -		return PTR_ERR(pci->dbi_base);
> +	/*
> +	 * For the broken DTs that supply 'dbi' as 'elbi', parse the 'elbi'
> +	 * region and assign it to both 'pci->elbi_base' and 'pci->dbi_space' so
> +	 * that the DWC core can skip parsing both regions.
> +	 */
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "elbi");
> +	if (res) {
> +		pci->elbi_base = devm_pci_remap_cfg_resource(pci->dev, res);
> +		if (IS_ERR(pci->elbi_base))
> +			return PTR_ERR(pci->elbi_base);
> +
> +		pci->dbi_base = pci->elbi_base;
> +		pci->dbi_phys_addr = res->start;
> +	}
>   
>   	mp->cfg_base = devm_platform_ioremap_resource_byname(pdev, "cfg");
>   	if (IS_ERR(mp->cfg_base))
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index c644216995f69cbf065e61a0392bf1e5e32cf56e..06eca858eb1b3c7a8a833df6616febcdbe854850 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -168,11 +168,13 @@ int dw_pcie_get_resources(struct dw_pcie *pci)
>   	}
>   
>   	/* ELBI is an optional resource */
> -	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "elbi");
> -	if (res) {
> -		pci->elbi_base = devm_ioremap_resource(pci->dev, res);
> -		if (IS_ERR(pci->elbi_base))
> -			return PTR_ERR(pci->elbi_base);
> +	if (!pci->elbi_base) {
> +		res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "elbi");
> +		if (res) {
> +			pci->elbi_base = devm_ioremap_resource(pci->dev, res);
> +			if (IS_ERR(pci->elbi_base))
> +				return PTR_ERR(pci->elbi_base);
> +		}
>   	}
>   
>   	/* LLDD is supposed to manually switch the clocks and resets state */
> 

Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>