Re: [PATCH v2 5/9] PCI: dwc: Replace certain BAR_RESERVED with BAR_DISABLED in glue drivers

[Frank Li <Frank.li@nxp.com>]

On Wed, Feb 25, 2026 at 06:03:28PM +0100, Niklas Cassel wrote:
> Most DWC based EPC glue drivers that have BARs marked as BAR_RESERVED in
> epc_features also call dw_pcie_ep_reset_bar() for these reserved BARs in
> ep->ops->init(). (The only exception is pci-keystone.c.)
>
> An EPF driver will be able to get/enable BARs that have been disabled/reset
> using dw_pcie_ep_reset_bar(), except if the BAR is marked as BAR_RESERVED
> (see pci_epc_get_next_free_bar()).
>
> Thus, all EPC drivers that have BARs marked as BAR_RESERVED in epc_features
> and call dw_pcie_ep_reset_bar(), should really have these BARs marked as
> BAR_DISABLED. If dw_pcie_ep_reset_bar() is not called by the glue driver,
> the BARs are kept as BAR_RESERVED.
>
> No EPC drivers outside drivers/pci/controllers/dwc mark their BARs as
> BAR_RESERVED, so there is nothing to do in non-DWC based EPC drivers.
>
> Tested-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
> Signed-off-by: Niklas Cassel <cassel@kernel.org>
> ---

Reviewed-by: Frank Li <Frank.Li@nxp.com>
>  drivers/pci/controller/dwc/pci-imx6.c         | 12 ++++++------
>  drivers/pci/controller/dwc/pci-keystone.c     | 12 ++++++++++++
>  drivers/pci/controller/dwc/pcie-rcar-gen4.c   |  6 +++---
>  drivers/pci/controller/dwc/pcie-tegra194.c    |  8 ++++----
>  drivers/pci/controller/dwc/pcie-uniphier-ep.c |  4 ++--
>  5 files changed, 27 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index a5b8d0b71677..ec1e3557ca53 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -1433,19 +1433,19 @@ static int imx_pcie_ep_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
>  static const struct pci_epc_features imx8m_pcie_epc_features = {
>  	DWC_EPC_COMMON_FEATURES,
>  	.msi_capable = true,
> -	.bar[BAR_1] = { .type = BAR_RESERVED, },
> -	.bar[BAR_3] = { .type = BAR_RESERVED, },
> +	.bar[BAR_1] = { .type = BAR_DISABLED, },
> +	.bar[BAR_3] = { .type = BAR_DISABLED, },
>  	.bar[BAR_4] = { .type = BAR_FIXED, .fixed_size = SZ_256, },
> -	.bar[BAR_5] = { .type = BAR_RESERVED, },
> +	.bar[BAR_5] = { .type = BAR_DISABLED, },
>  	.align = SZ_64K,
>  };
>
>  static const struct pci_epc_features imx8q_pcie_epc_features = {
>  	DWC_EPC_COMMON_FEATURES,
>  	.msi_capable = true,
> -	.bar[BAR_1] = { .type = BAR_RESERVED, },
> -	.bar[BAR_3] = { .type = BAR_RESERVED, },
> -	.bar[BAR_5] = { .type = BAR_RESERVED, },
> +	.bar[BAR_1] = { .type = BAR_DISABLED, },
> +	.bar[BAR_3] = { .type = BAR_DISABLED, },
> +	.bar[BAR_5] = { .type = BAR_DISABLED, },
>  	.align = SZ_64K,
>  };
>
> diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c
> index 20fa4dadb82a..278d2dba1db0 100644
> --- a/drivers/pci/controller/dwc/pci-keystone.c
> +++ b/drivers/pci/controller/dwc/pci-keystone.c
> @@ -933,6 +933,18 @@ static const struct pci_epc_features ks_pcie_am654_epc_features = {
>  	DWC_EPC_COMMON_FEATURES,
>  	.msi_capable = true,
>  	.msix_capable = true,
> +	/*
> +	 * TODO: This driver is the only DWC glue driver that had BAR_RESERVED
> +	 * BARs, but did not call dw_pcie_ep_reset_bar() for the reserved BARs.
> +	 *
> +	 * To not change the existing behavior, these BARs were not migrated to
> +	 * BAR_DISABLED. If this driver wants the BAR_RESERVED BARs to be
> +	 * disabled, it should migrate them to BAR_DISABLED.
> +	 *
> +	 * If they actually should be enabled, then the driver must also define
> +	 * what is behind these reserved BARs, see the definition of struct
> +	 * pci_epc_bar_rsvd_region.
> +	 */
>  	.bar[BAR_0] = { .type = BAR_RESERVED, },
>  	.bar[BAR_1] = { .type = BAR_RESERVED, },
>  	.bar[BAR_2] = { .type = BAR_RESIZABLE, },
> diff --git a/drivers/pci/controller/dwc/pcie-rcar-gen4.c b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> index a6912e85e4dd..9dd05bac22b9 100644
> --- a/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> +++ b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> @@ -422,10 +422,10 @@ static int rcar_gen4_pcie_ep_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
>  static const struct pci_epc_features rcar_gen4_pcie_epc_features = {
>  	DWC_EPC_COMMON_FEATURES,
>  	.msi_capable = true,
> -	.bar[BAR_1] = { .type = BAR_RESERVED, },
> -	.bar[BAR_3] = { .type = BAR_RESERVED, },
> +	.bar[BAR_1] = { .type = BAR_DISABLED, },
> +	.bar[BAR_3] = { .type = BAR_DISABLED, },
>  	.bar[BAR_4] = { .type = BAR_FIXED, .fixed_size = 256 },
> -	.bar[BAR_5] = { .type = BAR_RESERVED, },
> +	.bar[BAR_5] = { .type = BAR_DISABLED, },
>  	.align = SZ_1M,
>  };
>
> diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
> index 31aa9a494dbc..9f9453e8cd23 100644
> --- a/drivers/pci/controller/dwc/pcie-tegra194.c
> +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
> @@ -1994,10 +1994,10 @@ static const struct pci_epc_features tegra_pcie_epc_features = {
>  	.bar[BAR_0] = { .type = BAR_FIXED, .fixed_size = SZ_1M,
>  			.only_64bit = true, },
>  	.bar[BAR_1] = { .type = BAR_64BIT_UPPER, },
> -	.bar[BAR_2] = { .type = BAR_RESERVED, },
> -	.bar[BAR_3] = { .type = BAR_RESERVED, },
> -	.bar[BAR_4] = { .type = BAR_RESERVED, },
> -	.bar[BAR_5] = { .type = BAR_RESERVED, },
> +	.bar[BAR_2] = { .type = BAR_DISABLED, },
> +	.bar[BAR_3] = { .type = BAR_DISABLED, },
> +	.bar[BAR_4] = { .type = BAR_DISABLED, },
> +	.bar[BAR_5] = { .type = BAR_DISABLED, },
>  	.align = SZ_64K,
>  };
>
> diff --git a/drivers/pci/controller/dwc/pcie-uniphier-ep.c b/drivers/pci/controller/dwc/pcie-uniphier-ep.c
> index f873a1659592..5bde3ee682b5 100644
> --- a/drivers/pci/controller/dwc/pcie-uniphier-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-uniphier-ep.c
> @@ -429,8 +429,8 @@ static const struct uniphier_pcie_ep_soc_data uniphier_pro5_data = {
>  		.bar[BAR_1] = { .type = BAR_64BIT_UPPER, },
>  		.bar[BAR_2] = { .only_64bit = true, },
>  		.bar[BAR_3] = { .type = BAR_64BIT_UPPER, },
> -		.bar[BAR_4] = { .type = BAR_RESERVED, },
> -		.bar[BAR_5] = { .type = BAR_RESERVED, },
> +		.bar[BAR_4] = { .type = BAR_DISABLED, },
> +		.bar[BAR_5] = { .type = BAR_DISABLED, },
>  	},
>  };
>
> --
> 2.53.0
>