Subject: Re: [PATCH net-next v2 5/8] net: macb: timer adjust mode is not supported

From: Simon Horman <[email-masked]>
Date: Sun, 1 Mar 2026 18:12:33 +0000

On Thu, Feb 26, 2026 at 11:03:20AM +0000, Conor Dooley wrote:
> From: Conor Dooley <[email-masked]>
> 
> The ptp portion of this driver controls the tsu's timer using the
> controls for "increment mode", which is not compatible with the hardware
> trying to control it via the gem_tsu_inc_ctrl and gem_tsu_ms inputs in
> "timer adjust mode". Abort probe if the property signalling that the
> relevant signals have been wired up is present.
> 
> Signed-off-by: Conor Dooley <[email-masked]>
> ---
>  drivers/net/ethernet/cadence/macb_main.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index ddbb0c327b303..fa55e6e7036f2 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -5535,6 +5535,12 @@ static int macb_probe(struct platform_device *pdev)
>  
>  	bp->usrio = macb_config->usrio;
>  
> +	if (of_property_read_bool(bp->pdev->dev.of_node, "cdns,timer-adjust") &&
> +			IS_ENABLED(CONFIG_MACB_USE_HWSTAMP)) {
> +		dev_err(&pdev->dev, "Timer adjust mode is not supported\n");

Hi Conor,

Assuming this is an error condition I think that err should
be set to an negative error value here. Else the function will return 0.

Flagged by Smatch.

> +		goto err_out_free_netdev;
> +	}
> +
>  	/* By default we set to partial store and forward mode for zynqmp.
>  	 * Disable if not set in devicetree.
>  	 */
> -- 
> 2.51.0
> 
>