Re: [PATCH v4 2/4] PCI: dwc: Improve msg_atu_index error handling

[Damien Le Moal <dlemoal@kernel.org>]

On 2026/01/24 5:28, Niklas Cassel wrote:
> Only try to dedicate an outbound iATU to MSG TLP if use_atu_msg is set.
> If use_atu_msg is not set, it is completely useless to bump the index.
> 
> Additionally, if use_atu_msg is set, and there is no outbound iATU
> available, return an error.
> 
> Fixes: e1a4ec1a9520 ("PCI: dwc: Add generic MSG TLP support for sending PME_Turn_Off when system suspend")
> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>
> Signed-off-by: Niklas Cassel <cassel@kernel.org>
> ---
>  drivers/pci/controller/dwc/pcie-designware-host.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index ae5f2d8a3857..d7f57d77bdf5 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -982,7 +982,14 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
>  		dev_warn(pci->dev, "Ranges exceed outbound iATU size (%d)\n",
>  			 pci->num_ob_windows);
>  
> -	pp->msg_atu_index = ++i;
> +	if (pp->use_atu_msg) {
> +		if (pci->num_ob_windows > ++i) {

	if (pp->use_atu_msg) {
		i++;
		if (pci->num_ob_windows > i) {

is far more readable in my opinion.

> +			pp->msg_atu_index = i;
> +		} else {
> +			dev_err(pci->dev, "Cannot add outbound window for MSG TLP\n");
> +			return -ENOMEM;
> +		}
> +	}

Seeing this, I do not really see the point of the previous patch since you
completely nuke that change here. So maybe drop patch 1 ?

>  
>  	i = 0;
>  	resource_list_for_each_entry(entry, &pp->bridge->dma_ranges) {


-- 
Damien Le Moal
Western Digital Research