[PATCH v2 1/2] media: rcar-isp: distinguish absent cores from registration failures

[Myeonghun Pak <mhun512@gmail.com>]

risp_core_probe() clears core->base when resource setup fails. Once
resource setup has succeeded, it leaves core->base set while unwinding
errors from the remaining registration steps, including destruction of
core->rpp and release of the VSPX device reference.

risp_probe() treats every -ENODEV from risp_core_probe() as an absent
optional core. If a later registration step returns that error, the
parent probe can continue and subsequently call risp_core_remove() on
resources that have already been released.

Only accept -ENODEV as an absent core when core->base is NULL. Otherwise,
propagate the error through the parent probe's subdevice cleanup. This
also keeps failures from the later IRQ request in the following patch
from being mistaken for an absent core.

This issue was identified during our ongoing research while reviewing
kernel code.

Fixes: 2151350f60d1 ("media: rcar-isp: Add support for ISPCORE")
Assisted-by: LLM
Co-developed-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
---
Changes in v2:
- Split the -ENODEV handling out of the IRQ lifetime fix, as requested
  by Niklas Soderlund.

v1: https://lore.kernel.org/r/20261011214448.2043581-1-mhun512@gmail.com

Compile-tested with Clang 22.1.2, W=1 (arm64). No runtime testing.

 drivers/media/platform/renesas/rcar-isp/csisp.c | 2 ++
 1 file changed, 2 insertions(+)
diff --git a/drivers/media/platform/renesas/rcar-isp/csisp.c b/drivers/media/platform/renesas/rcar-isp/csisp.c
index 53ce47020d170454b3d208bce7f4d6aad76764d3..73bf7e42bad2ac1ec2493cd8ec81003cce05a3dd 100644
--- a/drivers/media/platform/renesas/rcar-isp/csisp.c
+++ b/drivers/media/platform/renesas/rcar-isp/csisp.c
@@ -563,6 +563,8 @@ static int risp_probe(struct platform_device *pdev)
 		isp->subdev.internal_ops = &risp_cs_internal_ops;
 		break;
 	case -ENODEV:
+		if (isp->core.base)
+			goto error_subdev;
 		/* The device don't have an ISP core, that is OK. */
 		ret = 0;
 		break;