linux-kernel - Re: [PATCH v3 1/5] PCI: dwc: Skip failed outbound iATU and continue

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Message-ID: <20250923144223.GA2032427@bhelgaas>
Date: Tue, 23 Sep 2025 09:42:23 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Randolph Lin <randolph@...estech.com>
Cc: linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-riscv@...ts.infradead.org, devicetree@...r.kernel.org,
	jingoohan1@...il.com, mani@...nel.org, lpieralisi@...nel.org,
	kwilczynski@...nel.org, robh@...nel.org, bhelgaas@...gle.com,
	krzk+dt@...nel.org, conor+dt@...nel.org, alex@...ti.fr,
	aou@...s.berkeley.edu, palmer@...belt.com, paul.walmsley@...ive.com,
	ben717@...estech.com, inochiama@...il.com,
	thippeswamy.havalige@....com, namcao@...utronix.de,
	shradha.t@...sung.com, randolph.sklin@...il.com,
	tim609@...estech.com
Subject: Re: [PATCH v3 1/5] PCI: dwc: Skip failed outbound iATU and continue

On Tue, Sep 23, 2025 at 07:36:43PM +0800, Randolph Lin wrote:
> Previously, outbound iATU programming included range checks based
> on hardware limitations. If a configuration did not meet these
> constraints, the loop would stop immediately.
> 
> This patch updates the behavior to enhance flexibility. Instead of
> stopping at the first issue, it now logs a warning with details of
> the affected window and proceeds to program the remaining iATU
> entries.
> 
> This enables partial configuration to complete in cases where some
> iATU windows may not meet requirements, improving overall
> compatibility.

It's not really clear why this is needed.  I assume it's related to
dropping qilai_pcie_outbound_atu_addr_valid().

I guess dw_pcie_prog_outbound_atu() must return an error for one of
the QiLai ranges?  Which one, and what exactly is the problem?  I
still suspect something wrong in the devicetree description.

> Signed-off-by: Randolph Lin <randolph@...estech.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware-host.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 952f8594b501..91ee6b903934 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -756,7 +756,7 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
>  		if (resource_type(entry->res) != IORESOURCE_MEM)
>  			continue;
>  
> -		if (pci->num_ob_windows <= ++i)
> +		if (pci->num_ob_windows <= i)
>  			break;
>  
>  		atu.index = i;
> @@ -773,9 +773,10 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
>  
>  		ret = dw_pcie_prog_outbound_atu(pci, &atu);
>  		if (ret) {
> -			dev_err(pci->dev, "Failed to set MEM range %pr\n",
> -				entry->res);
> -			return ret;
> +			dev_warn(pci->dev, "Failed to set MEM range %pr\n",
> +				 entry->res);
> +		} else {
> +			i++;
>  		}
>  	}
>  
> -- 
> 2.34.1
> 
> 
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