Re: [PATCH 1/2] PCI: dwc: Correct iATU index increment for MSG TLP region

[Frank Li]

On Wed, Dec 03, 2025 at 11:50:14AM +0530, Krishna Chaitanya Chundru wrote:
> Commit e1a4ec1a9520 ("PCI: dwc: Add generic MSG TLP support for sending
> PME_Turn_Off when system suspend") introduced a mechanism to reserve an
> iATU window for MSG TLP transactions. However, the code incorrectly
> assigned pp->msg_atu_index = i without incrementing i first, causing
> the MSG TLP region to reuse the last configured outbound window instead
> of the next available one. This can cause issue with IO transfers as
> this can over write iATU configured for IO memory.
>
> Fix this by incrementing i before assigning it to msg_atu_index so
> that the MSG TLP region uses a dedicated iATU entry.
>
> Fixes: e1a4ec1a9520 ("PCI: dwc: Add generic MSG TLP support for sending PME_Turn_Off when system suspend")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@xxxxxxxxxxxxxxxx>

Thank you fix it.

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
> ---
>  drivers/pci/controller/dwc/pcie-designware-host.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index e92513c5bda51bde3a7157033ddbd73afa370d78..4fb6331fbc2b322c1a1b6a8e4fe08f92e170da19 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -942,7 +942,7 @@ 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;
> +	pp->msg_atu_index = ++i;
>
>  	i = 0;
>  	resource_list_for_each_entry(entry, &pp->bridge->dma_ranges) {
>
> --
> 2.34.1
>