drm/amd/display: add missing NULL check for DML2

Recently, the driver introduce DML2 for future ASIC support.
But, some ASIC's hubbub pointer is null before calling.
It cause the below null pointer issue, so add null check to fix it.

BUG: kernel NULL pointer dereference, address: 0000000000000000
RIP: 0010:dc_create_resource_pool+0xc1/0x2c0 [amdgpu] Call Trace:
 <TASK>
 ? show_regs.cold+0x1a/0x1f
 ? __die_body+0x20/0x70
 ? __die+0x2b/0x37
 ? page_fault_oops+0x136/0x2c0
 ? do_user_addr_fault+0x303/0x660
 ? exc_page_fault+0x77/0x170
 ? asm_exc_page_fault+0x27/0x30
 ? dc_create_resource_pool+0xc1/0x2c0 [amdgpu]  ? dc_create_resource_pool+0x243/0x2c0 [amdgpu]
 dc_create+0x23f/0x6b0 [amdgpu]
 ? dmi_matches+0xa3/0x200
 amdgpu_dm_init+0x2bd/0x22a0 [amdgpu]

Fixes: 7966f319c66d ("drm/amd/display: Introduce DML2")
Signed-off-by: Bob Zhou <bob.zhou@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
index a7e49c78c18760475e2c1a3dd1ec6fd5e0269f69..97f402123fbba259bfb1fb8e3ae4818a9e2253ce 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
@@ -321,7 +321,7 @@ struct resource_pool *dc_create_resource_pool(struct dc  *dc,
                                res_pool->ref_clocks.xtalin_clock_inKhz;
                        res_pool->ref_clocks.dchub_ref_clock_inKhz =
                                res_pool->ref_clocks.xtalin_clock_inKhz;
-                       if ((res_pool->hubbub->funcs->get_dchub_ref_freq))
+                       if (res_pool->hubbub && res_pool->hubbub->funcs->get_dchub_ref_freq)
                                res_pool->hubbub->funcs->get_dchub_ref_freq(res_pool->hubbub,
                                        res_pool->ref_clocks.dccg_ref_clock_inKhz,
                                        &res_pool->ref_clocks.dchub_ref_clock_inKhz);