[PATCH v3 4/6] drm/rockchip: Fix vmap address caching in rockchip_gem_prime_vmap()

[Jiaqi <shijiaqi_develop@163.com>]

In rockchip_gem_prime_vmap(), when rk_obj->kvaddr is NULL, a new
vmap() is performed but the resulting virtual address is only stored in
the local variable 'vaddr', not saved to rk_obj->kvaddr.

This causes three problems:
1. Every subsequent prime_vmap call re-maps the same pages, wasting
   kernel virtual address space and TLB resources.
2. If the gem object is freed before prime_vunmap is called (e.g., in
   an error path), rockchip_gem_free_iommu() calls vunmap(rk_obj->kvaddr)
   which is NULL, so the prime_vmap-created mapping is never freed.
3. Multiple concurrent mappings of the same object cannot be tracked.

Fix by saving the newly vmap()'d address to rk_obj->kvaddr so it can
be reused and properly cleaned up.

Signed-off-by: Jiaqi <shijiaqi_develop@163.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
index 8afabe2118a9..1234567890ab 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
@@ -520,6 +520,7 @@ int rockchip_gem_prime_vmap(struct drm_gem_object *obj, struct iosys_map *map)
 		if (!vaddr)
 			return -ENOMEM;
 		iosys_map_set_vaddr(map, vaddr);
+		rk_obj->kvaddr = vaddr;
 		return 0;
 	}

--
2.40.0