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

[Jie Gan]

Hi Leo

On 4/7/2026 4:10 PM, Leo Yan wrote:
> 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.

Actually, we havent MMIO access for the static TPDM device, So no issues 
are observed. The commit message here may be misleading. do I need 
rephrase the commit message?

Thanks,
Jie

> 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>