On 13/08/2024 22:03, Vladimir Zapolskiy wrote:

There is a chance to meet runtime issues during configuration of CAMSS power domains, because on the error path dev_pm_domain_detach() is unexpectedly called with NULL or error pointer.

One of the simplest ways to reproduce the problem is to probe CAMSS driver before registration of CAMSS power domains, for instance if a platform CAMCC driver is simply not built.

Warning backtrace example:

 Unable to handle kernel NULL pointer dereference at virtual address 00000000000001a2

 <snip>

 pc : dev_pm_domain_detach+0x8/0x48
 lr : camss_probe+0x374/0x9c0

 <snip>

 Call trace:
  dev_pm_domain_detach+0x8/0x48
  platform_probe+0x70/0xf0
  really_probe+0xc4/0x2a8
  __driver_probe_device+0x80/0x140
  driver_probe_device+0x48/0x170
  __device_attach_driver+0xc0/0x148
  bus_for_each_drv+0x88/0xf0
  __device_attach+0xb0/0x1c0
  device_initial_probe+0x1c/0x30
  bus_probe_device+0xb4/0xc0
  deferred_probe_work_func+0x90/0xd0
  process_one_work+0x164/0x3e0
  worker_thread+0x310/0x420
  kthread+0x120/0x130
  ret_from_fork+0x10/0x20

Fixes: 23aa4f0cd327 ("media: qcom: camss: Move VFE power-domain specifics into vfe.c") Signed-off-by: Vladimir Zapolskiy vladimir.zapolskiy@linaro.org

---

The first version of the patch and discussion is found over here:

https://lore.kernel.org/all/20240806221204.1560258-1-vladimir.zapolskiy@lina...

Changes from v1 to v2:

• added an encountered runtime warning to the commit message per ask from Bryan.

I tested this fix in both cases of set and unset "power-domain-names" property in camss device tree node, and I didn't find any negative side effects of the fix.

drivers/media/platform/qcom/camss/camss.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/drivers/media/platform/qcom/camss/camss.c b/drivers/media/platform/qcom/camss/camss.c index 51b1d3550421..aa894be1461d 100644 --- a/drivers/media/platform/qcom/camss/camss.c +++ b/drivers/media/platform/qcom/camss/camss.c

+ stable@vger.kernel.org

Reviewed-by: Bryan O'Donoghue bryan.odonoghue@linaro.org