[bug report] remoteproc: imx_rproc: Introduce prepare ops for imx_rproc_dcfg

[bug report] remoteproc: imx_rproc: Introduce prepare ops for imx_rproc_dcfg

[Dan Carpenter]

[ Smatch checking is paused while we raise funding.  #SadFace
  https://lore.kernel.org/all/aTaiGSbWZ9DJaGo7@stanley.mountain/ -dan ]

Hello Peng Fan,

Commit edd2a9956055 ("remoteproc: imx_rproc: Introduce prepare ops
for imx_rproc_dcfg") from Jan 9, 2026 (linux-next), leads to the
following Smatch static checker warning:

	drivers/remoteproc/imx_rproc.c:648 imx_rproc_prepare()
	warn: ignoring unreachable code.

drivers/remoteproc/imx_rproc.c
    605 static int imx_rproc_prepare(struct rproc *rproc)
    606 {
    607         struct imx_rproc *priv = rproc->priv;
    608         struct device_node *np = priv->dev->of_node;
    609         struct rproc_mem_entry *mem;
    610         int i = 0;
    611         u32 da;
    612 
    613         /* Register associated reserved memory regions */
    614         while (1) {
    615                 int err;
    616                 struct resource res;
    617 
    618                 err = of_reserved_mem_region_to_resource(np, i++, &res);
    619                 if (err)
    620                         return 0;
    621 
    622                 /*
    623                  * Ignore the first memory region which will be used vdev buffer.
    624                  * No need to do extra handlings, rproc_add_virtio_dev will handle it.
    625                  */
    626                 if (strstarts(res.name, "vdev0buffer"))
    627                         continue;
    628 
    629                 if (strstarts(res.name, "rsc-table"))
    630                         continue;
    631 
    632                 /* No need to translate pa to da, i.MX use same map */
    633                 da = res.start;
    634 
    635                 /* Register memory region */
    636                 mem = rproc_mem_entry_init(priv->dev, NULL, (dma_addr_t)res.start,
    637                                            resource_size(&res), da,
    638                                            imx_rproc_mem_alloc, imx_rproc_mem_release,
    639                                            "%.*s", strchrnul(res.name, '@') - res.name,
    640                                            res.name);
    641                 if (!mem)
    642                         return -ENOMEM;
    643 
    644                 rproc_coredump_add_segment(rproc, da, resource_size(&res));
    645                 rproc_add_carveout(rproc, mem);
    646         }
    647 
--> 648         if (priv->ops && priv->ops->prepare)
    649                 return priv->ops->prepare(rproc);

This is unreachable code.

    650 
    651         return 0;
    652 }

regards,
dan carpenter

Re: [bug report] remoteproc: imx_rproc: Introduce prepare ops for imx_rproc_dcfg

[Mathieu Poirier]

On Fri, Feb 06, 2026 at 04:41:13PM +0300, Dan Carpenter wrote:
> [ Smatch checking is paused while we raise funding.  #SadFace
>   https://lore.kernel.org/all/aTaiGSbWZ9DJaGo7@stanley.mountain/ -dan ]
> 
> Hello Peng Fan,
> 
> Commit edd2a9956055 ("remoteproc: imx_rproc: Introduce prepare ops
> for imx_rproc_dcfg") from Jan 9, 2026 (linux-next), leads to the
> following Smatch static checker warning:
> 
> 	drivers/remoteproc/imx_rproc.c:648 imx_rproc_prepare()
> 	warn: ignoring unreachable code.
> 
> drivers/remoteproc/imx_rproc.c
>     605 static int imx_rproc_prepare(struct rproc *rproc)
>     606 {
>     607         struct imx_rproc *priv = rproc->priv;
>     608         struct device_node *np = priv->dev->of_node;
>     609         struct rproc_mem_entry *mem;
>     610         int i = 0;
>     611         u32 da;
>     612 
>     613         /* Register associated reserved memory regions */
>     614         while (1) {
>     615                 int err;
>     616                 struct resource res;
>     617 
>     618                 err = of_reserved_mem_region_to_resource(np, i++, &res);
>     619                 if (err)
>     620                         return 0;
>     621 
>     622                 /*
>     623                  * Ignore the first memory region which will be used vdev buffer.
>     624                  * No need to do extra handlings, rproc_add_virtio_dev will handle it.
>     625                  */
>     626                 if (strstarts(res.name, "vdev0buffer"))
>     627                         continue;
>     628 
>     629                 if (strstarts(res.name, "rsc-table"))
>     630                         continue;
>     631 
>     632                 /* No need to translate pa to da, i.MX use same map */
>     633                 da = res.start;
>     634 
>     635                 /* Register memory region */
>     636                 mem = rproc_mem_entry_init(priv->dev, NULL, (dma_addr_t)res.start,
>     637                                            resource_size(&res), da,
>     638                                            imx_rproc_mem_alloc, imx_rproc_mem_release,
>     639                                            "%.*s", strchrnul(res.name, '@') - res.name,
>     640                                            res.name);
>     641                 if (!mem)
>     642                         return -ENOMEM;
>     643 
>     644                 rproc_coredump_add_segment(rproc, da, resource_size(&res));
>     645                 rproc_add_carveout(rproc, mem);
>     646         }
>     647 
> --> 648         if (priv->ops && priv->ops->prepare)
>     649                 return priv->ops->prepare(rproc);
> 
> This is unreachable code.

It looks like Dan (and Smatch) has a point.

> 
>     650 
>     651         return 0;
>     652 }
> 
> regards,
> dan carpenter
> 

RE: [bug report] remoteproc: imx_rproc: Introduce prepare ops for imx_rproc_dcfg

[Peng Fan]

Hi Dan,

Thanks for your report.

> Subject: [bug report] remoteproc: imx_rproc: Introduce prepare ops for
> imx_rproc_dcfg
> 
> Hello Peng Fan,
> 
> Commit edd2a9956055 ("remoteproc: imx_rproc: Introduce prepare
> ops for imx_rproc_dcfg") from Jan 9, 2026 (linux-next), leads to the
> following Smatch static checker warning:
> 
> 	drivers/remoteproc/imx_rproc.c:648 imx_rproc_prepare()
> 	warn: ignoring unreachable code.
> 
> drivers/remoteproc/imx_rproc.c

[...]
>     642                         return -ENOMEM;
>     643
>     644                 rproc_coredump_add_segment(rproc, da,
> resource_size(&res));
>     645                 rproc_add_carveout(rproc, mem);
>     646         }
>     647
> --> 648         if (priv->ops && priv->ops->prepare)
>     649                 return priv->ops->prepare(rproc);
> 
> This is unreachable code.

Indeed.

The i.MX95 patches were developed quite some time ago. Later, there was
another change [1] which modified the reserved-memory while-loop logic.
When rebasing my changes on top of that, I overlooked this behavior
change, which resulted in the early return making the prepare callback
unreachable.

Regarding why this was not exposed earlier during testing: NXP U-Boot
powers up the M7 (leaving it in reset) and initializes TCM ECC by default.
As a result, even without calling the platform prepare ops, Linux can
still load the M7 ELF correctly, so no issue was observed.

In hindsight, I should have tested the case where M7 remains powered off
when rebasing these changes (:

I have just sent out a fix to address this issue. Thanks again for
reporting it.

[1] 67a7bc7f0358b ("remoteproc: Use of_reserved_mem_region_* functions for "memory-region")

Thanks,
Peng

>     650
>     651         return 0;
>     652 }
> 
> regards,
> dan carpenter