Re: [PATCH v7 2/2] remoteproc: qcom: Use of_reserved_mem_region_* functions for "memory-region"

[Rob Herring <robh@kernel.org>]

On Thu, Nov 27, 2025 at 8:28 AM Marek Szyprowski
<m.szyprowski@samsung.com> wrote:
>
> Hi Rob,
>
> On 24.11.2025 19:27, Rob Herring (Arm) wrote:
> > Use the newly added of_reserved_mem_region_to_resource() and
> > of_reserved_mem_region_count() functions to handle "memory-region"
> > properties.
> >
> > The error handling is a bit different in some cases. Often
> > "memory-region" is optional, so failed lookup is not an error. But then
> > an error in of_reserved_mem_lookup() is treated as an error. However,
> > that distinction is not really important. Either the region is available
> > and usable or it is not. So now, it is just
> > of_reserved_mem_region_to_resource() which is checked for an error.
> >
> > Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
>
> This patch landed in today's linux-next as commit c70b9d5fdcd7
> ("remoteproc: qcom: Use of_reserved_mem_region_* functions for
> "memory-region""). In my tests I found that it breaks booting of
> DragonBoard410c (arch/arm64/boot/dts/qcom/apq8016-sbc.dts) by causing
> the NULL pointer dereference. The issue is caused by replacing
> devm_ioremap_wc() with devm_ioremap_resource_wc(), which fails on
> devm_request_mem_region(), see comment in the code below. It looks that
> the error handling is somewhere broken. Here is the the kernel log:
>
> remoteproc remoteproc0: 4080000.remoteproc is available
> qcom-wcnss-pil a204000.remoteproc: error -EBUSY: can't request region
> for resource [mem 0x8e200000-0x8e7fffff]
> remoteproc remoteproc1: a204000.remoteproc is available
> remoteproc remoteproc1: powering up a204000.remoteproc
> remoteproc remoteproc1: Booting fw image qcom/apq8016/wcnss.mbn, size
> 4111376
> Unable to handle kernel paging request at virtual address fffffffffffffff0
> Mem abort info:
> ...
> Internal error: Oops: 0000000096000046 [#1]  SMP
> Modules linked in: cpufreq_powersave qcom_wcnss_pil cpufreq_conservative
> coresight_stm coresight_replicator coresight_tmc coresight_tpiu stm_core
> coresight_funnel coresight_cpu_debug coresight_cti(+) adv7511 coresight
> nfc rfkill msm snd_soc_lpass_apq8016 snd_soc_apq8016_sbc
> snd_soc_lpass_cpu snd_soc_msm8916_analog snd_soc_msm8916_digital
> snd_soc_qcom_common snd_soc_lpass_platform snd_soc_core qrtr ubwc_config
> snd_compress llcc_qcom snd_pcm_dmaengine qcom_q6v5_mss snd_pcm ocmem
> qcom_pil_info qcom_spmi_vadc qcom_camss drm_gpuvm qcom_pon rtc_pm8xxx
> qcom_q6v5 qcom_spmi_temp_alarm venus_core qcom_vadc_common snd_timer
> drm_exec qcom_sysmon snd qcom_common gpu_sched videobuf2_dma_sg
> v4l2_mem2mem qcom_glink_smem v4l2_fwnode soundcore drm_dp_aux_bus
> qmi_helpers mdt_loader v4l2_async videobuf2_memops videobuf2_v4l2
> videodev qnoc_msm8916 videobuf2_common qcom_rng drm_display_helper mc
> qcom_stats rpmsg_ctrl rpmsg_char display_connector ramoops socinfo
> rmtfs_mem reed_solomon ax88796b asix usbnet phy_qcom_usb_hs ipv6 libsha1
> CPU: 2 UID: 0 PID: 28 Comm: kworker/2:0 Tainted: G W
> 6.18.0-rc1+ #16209 PREEMPT
> Tainted: [W]=WARN
> lr : __qcom_mdt_load+0x210/0x304 [mdt_loader]
> Call trace:
>   __pi_memcpy_generic+0x128/0x22c (P)
>   qcom_mdt_load+0x68/0x60c [mdt_loader]
>   wcnss_load+0x2c/0x5c [qcom_wcnss_pil]
>   rproc_start+0x30/0x1b4
>   rproc_boot+0x19c/0x560
>   rproc_auto_boot_callback+0x1c/0x34
>   request_firmware_work_func+0x4c/0x98
>   process_one_work+0x208/0x60c
>   worker_thread+0x244/0x388
>   kthread+0x150/0x228
>   ret_from_fork+0x10/0x20
> Code: 927cec03 cb0e0021 8b0e0042 a9411c26 (a900340c)
> ---[ end trace 0000000000000000 ]---
>
>
> > ---
> > v7:
> >   - Split QCom to separate patch
> > ---
> >   drivers/remoteproc/qcom_q6v5_adsp.c | 24 ++++------
> >   drivers/remoteproc/qcom_q6v5_mss.c  | 60 ++++++++-----------------
> >   drivers/remoteproc/qcom_q6v5_pas.c  | 69 +++++++++++------------------
> >   drivers/remoteproc/qcom_q6v5_wcss.c | 25 +++++------
> >   drivers/remoteproc/qcom_wcnss.c     | 23 ++++------
> >   5 files changed, 72 insertions(+), 129 deletions(-)
> >
>
> > ...
>
> > diff --git a/drivers/remoteproc/qcom_wcnss.c b/drivers/remoteproc/qcom_wcnss.c
> > index 2c7e519a2254..14005fb049a2 100644
> > --- a/drivers/remoteproc/qcom_wcnss.c
> > +++ b/drivers/remoteproc/qcom_wcnss.c
> > @@ -526,25 +526,20 @@ static int wcnss_request_irq(struct qcom_wcnss *wcnss,
> >
> >   static int wcnss_alloc_memory_region(struct qcom_wcnss *wcnss)
> >   {
> > -     struct reserved_mem *rmem = NULL;
> > -     struct device_node *node;
> > -
> > -     node = of_parse_phandle(wcnss->dev->of_node, "memory-region", 0);
> > -     if (node)
> > -             rmem = of_reserved_mem_lookup(node);
> > -     of_node_put(node);
> > +     struct resource res;
> > +     int ret;
> >
> > -     if (!rmem) {
> > +     ret = of_reserved_mem_region_to_resource(wcnss->dev->of_node, 0, &res);
> > +     if (ret) {
> >               dev_err(wcnss->dev, "unable to resolve memory-region\n");
> > -             return -EINVAL;
> > +             return ret;
> >       }
> >
> > -     wcnss->mem_phys = wcnss->mem_reloc = rmem->base;
> > -     wcnss->mem_size = rmem->size;
> > -     wcnss->mem_region = devm_ioremap_wc(wcnss->dev, wcnss->mem_phys, wcnss->mem_size);
> > +     wcnss->mem_phys = wcnss->mem_reloc = res.start;
> > +     wcnss->mem_size = resource_size(&res);
> > +     wcnss->mem_region = devm_ioremap_resource_wc(wcnss->dev, &res);
>
> The above line causes the failure. After restoring it to:
>
> wcnss->mem_region = devm_ioremap_wc(wcnss->dev, wcnss->mem_phys, wcnss->mem_size);
>
> the mentioned board boots fine again. I'm not sure about other drivers,
> if they also fail the same way as they might not be used on the tested
> board.

Other platforms (non-QCom) were tested also use
devm_ioremap_resource_wc(). So something else is claiming the same
region? Can you dump out /proc/iomem?

The region is dynamically allocated, so maybe that has something to do with it.

Rob