Re: [PATCH] coresight: tpdm: fix invalid MMIO access issue

[Leo Yan]

On Tue, Apr 07, 2026 at 12:47:11PM +0800, Jie Gan wrote:
> Create the csdev_access struct only when a valid MMIO resource is
> available. In tpdm_probe(), base is uninitialized for static TPDM
> instances that lack an MMIO resource, causing csdev_access to be
> created with a garbage address and potentially leading to
> unexpected issues.

This patch itself is fine for me.  However, I am wandering if this
is sufficient.

As mentioned "potentially leading to unexpected issues", can I
understand some code pieces access register with uninitialized base?
If so, you would also explictly add coresight_is_static_tpdm() to
prevent register access.

Thanks,
Leo

> Fixes: 14ae052f7947 ("coresight: tpdm: add static tpdm support")
> Signed-off-by: Jie Gan <jie.gan@xxxxxxxxxxxxxxxx>
> ---
>  drivers/hwtracing/coresight/coresight-tpdm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c b/drivers/hwtracing/coresight/coresight-tpdm.c
> index 9b16f368a58b..eaf7210af648 100644
> --- a/drivers/hwtracing/coresight/coresight-tpdm.c
> +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
> @@ -1430,6 +1430,7 @@ static int tpdm_probe(struct device *dev, struct resource *res)
>  		if (ret)
>  			return ret;
>  
> +		desc.access = CSDEV_ACCESS_IOMEM(base);
>  		if (tpdm_has_dsb_dataset(drvdata))
>  			of_property_read_u32(drvdata->dev->of_node,
>  					     "qcom,dsb-msrs-num", &drvdata->dsb_msr_num);
> @@ -1452,7 +1453,6 @@ static int tpdm_probe(struct device *dev, struct resource *res)
>  	desc.ops = &tpdm_cs_ops;
>  	desc.pdata = dev->platform_data;
>  	desc.dev = dev;
> -	desc.access = CSDEV_ACCESS_IOMEM(base);
>  	if (res)
>  		desc.groups = tpdm_attr_grps;
>  	else
> 
> ---
> base-commit: 816f193dd0d95246f208590924dd962b192def78
> change-id: 20260407-fix-potential-issue-in-tpdm-b07b44416051
> 
> Best regards,
> -- 
> Jie Gan <jie.gan@xxxxxxxxxxxxxxxx>
>