linux-kernel - Re: [PATCH v2 1/3] PCI: dwc: ep: Fix resizable BAR support for multi-PF configurations

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Message-ID: <aXHjRBEE7H3WwGXH@ryzen>
Date: Thu, 22 Jan 2026 09:46:17 +0100
From: Niklas Cassel <cassel@...nel.org>
To: Aksh Garg <a-garg7@...com>
Cc: linux-pci@...r.kernel.org, jingoohan1@...il.com, mani@...nel.org,
	lpieralisi@...nel.org, kwilczynski@...nel.org, robh@...nel.org,
	bhelgaas@...gle.com, linux-kernel@...r.kernel.org,
	s-vadapalli@...com, danishanwar@...com
Subject: Re: [PATCH v2 1/3] PCI: dwc: ep: Fix resizable BAR support for
 multi-PF configurations

On Thu, Jan 22, 2026 at 01:55:36PM +0530, Aksh Garg wrote:
> The resizable BAR support added by the commit 3a3d4cabe681
> ("PCI: dwc: ep: Allow EPF drivers to configure the size of Resizable
> BARs") incorrectly configures the resizable BARs only for the first
> Physical Function (PF0) in EP mode.
> 
> The resizable BAR configuration functions use generic dw_pcie_*_dbi
> operations instead of physical function specific dw_pcie_ep_*_dbi
> operations. This causes resizable BAR configuration to always target
> PF0 regardless of the requested function number.
> 
> Additionally, dw_pcie_ep_init_non_sticky_registers() only initializes
> resizable BAR registers for PF0, leaving other PFs unconfigured during
> the execution of this function.
> 
> Fix this by using physical function specific configuration space access
> operations throughout the resizable BAR code path and initializing
> registers for all the physical functions that support resizable BARs.
> 
> Fixes: 3a3d4cabe681 ("PCI: dwc: ep: Allow EPF drivers to configure the size of Resizable BARs")
> Signed-off-by: Aksh Garg <a-garg7@...com>
> Reviewed-by: Niklas Cassel <cassel@...nel.org>
> ---
> 
> Link to v1:
> https://lore.kernel.org/all/20260121054214.274429-2-a-garg7@ti.com/
> 
> Changes from v1 to v2:
> - Fixed the suggested nit
> 
>  .../pci/controller/dwc/pcie-designware-ep.c   | 48 ++++++++++++-------
>  1 file changed, 32 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index 19571ac2b961..1458477a6ba9 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -75,6 +75,13 @@ static u8 dw_pcie_ep_find_capability(struct dw_pcie_ep *ep, u8 func_no, u8 cap)
>  				 cap, ep, func_no);
>  }
>  
> +static u16 dw_pcie_ep_find_ext_capability(struct dw_pcie_ep *ep,
> +					  u8 func_no, u8 cap)
> +{
> +	return PCI_FIND_NEXT_EXT_CAP(dw_pcie_ep_read_cfg, 0,
> +				     cap, ep, func_no);
> +}
> +
>  /**
>   * dw_pcie_ep_hide_ext_capability - Hide a capability from the linked list
>   * @pci: DWC PCI device

I'm not sure to which branch Mani wants to apply this series.

But if the answer is pci/controller/dwc then this patch will not apply,
because the context lines "dw_pcie_ep_hide_ext_capability()" specifically
has been removed there.

If he intends to put this patch on the endpoint branch, then this comment
can be disregarded.


Kind regards,
Niklas