Hi,
On 07/04/2025 17:23, Luca Ceresoli wrote:
This is the new API for allocating DRM bridges.
This driver has a peculiar structure. zynqmp_dpsub.c is the actual driver,
which delegates to a submodule (zynqmp_dp.c) the allocation of a
sub-structure embedding the drm_bridge and its initialization, however it
does not delegate the drm_bridge_add(). Hence, following carefully the code
flow, it is correct to change the allocation function and .funcs assignment
in the submodule, while the drm_bridge_add() is not in that submodule.
Signed-off-by: Luca Ceresoli <luca.ceres...@bootlin.com>
---
Cc: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
Cc: Michal Simek <michal.si...@amd.com>
Cc: Tomi Valkeinen <tomi.valkei...@ideasonboard.com>
---
drivers/gpu/drm/xlnx/zynqmp_dp.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index
11d2415fb5a1f7fad03421898331289f2295d68b..de22b6457a78a7a2110f9f308d0b5a8700544010
100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -2439,9 +2439,9 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub)
struct zynqmp_dp *dp;
int ret;
- dp = kzalloc(sizeof(*dp), GFP_KERNEL);
- if (!dp)
- return -ENOMEM;
+ dp = devm_drm_bridge_alloc(&pdev->dev, struct zynqmp_dp, bridge,
&zynqmp_dp_bridge_funcs);
+ if (IS_ERR(dp))
+ return PTR_ERR(dp);
dp->dev = &pdev->dev;
dp->dpsub = dpsub;
@@ -2488,7 +2488,6 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub)
/* Initialize the bridge. */
bridge = &dp->bridge;
- bridge->funcs = &zynqmp_dp_bridge_funcs;
bridge->ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID
| DRM_BRIDGE_OP_HPD;
bridge->type = DRM_MODE_CONNECTOR_DisplayPort;
I haven't had time to look at this more, but jfyi: I got this when
unloading modules, but it doesn't seem to happen every time:
[ 103.010533] ------------[ cut here ]------------
[ 103.015415] refcount_t: underflow; use-after-free.
[ 103.020657] WARNING: CPU: 2 PID: 392 at lib/refcount.c:28
refcount_warn_saturate+0xf4/0x148
[ 103.029056] Modules linked in: zynqmp_dpsub(-) display_connector
drm_display_helper drm_dma_helper drm_kms_helper drm drm_p
anel_orientation_quirks
[ 103.042437] CPU: 2 UID: 0 PID: 392 Comm: rmmod Not tainted
6.15.0-rc2+ #3 PREEMPT
[ 103.050035] Hardware name: ZynqMP ZCU106 RevA (DT)
[ 103.054836] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS
BTYPE=--)
[ 103.061814] pc : refcount_warn_saturate+0xf4/0x148
[ 103.066632] lr : refcount_warn_saturate+0xf4/0x148
[ 103.071441] sp : ffff800083b5bbb0
[ 103.074766] x29: ffff800083b5bbb0 x28: ffff000806b23780 x27:
0000000000000000
[ 103.081953] x26: 0000000000000000 x25: 0000000000000000 x24:
ffff000801a68400
[ 103.089141] x23: ffff800081311a20 x22: ffff800083b5bc38 x21:
ffff000801a68010
[ 103.096329] x20: ffff0008040676c0 x19: ffff000804067240 x18:
0000000000000006
[ 103.103517] x17: 2e30303030303464 x16: 662d7968703a7968 x15:
ffff800083b5b5a0
[ 103.110705] x14: 0000000000000000 x13: 00000000000c0000 x12:
0000000000000000
[ 103.117892] x11: ffff80008163d6bc x10: 0000000000000028 x9 :
ffff800080ead38c
[ 103.125080] x8 : ffff800083b5b908 x7 : 0000000000000000 x6 :
ffff800083b5b9c0
[ 103.132268] x5 : ffff800083b5b948 x4 : 0000000000000001 x3 :
00000000000000db
[ 103.139455] x2 : 0000000000000000 x1 : 0000000000000000 x0 :
ffff000806b23780
[ 103.146644] Call trace:
[ 103.149102] refcount_warn_saturate+0xf4/0x148 (P)
[ 103.153918] drm_bridge_put.part.0+0x88/0xa0 [drm]
[ 103.159188] drm_bridge_put_void+0x1c/0x38 [drm]
[ 103.164231] devm_action_release+0x1c/0x30
[ 103.168354] release_nodes+0x68/0xa8
[ 103.171957] devres_release_all+0x98/0xf0
[ 103.175993] device_unbind_cleanup+0x20/0x70
[ 103.180291] device_release_driver_internal+0x208/0x250
[ 103.185542] driver_detach+0x54/0xa8
[ 103.189145] bus_remove_driver+0x78/0x108
[ 103.193181] driver_unregister+0x38/0x70
[ 103.197131] platform_driver_unregister+0x1c/0x30
[ 103.201862] zynqmp_dpsub_driver_exit+0x18/0x1100 [zynqmp_dpsub]
[ 103.207931] __arm64_sys_delete_module+0x1a8/0x2d0
[ 103.212748] invoke_syscall+0x50/0x120
[ 103.216524] el0_svc_common.constprop.0+0x48/0xf0
[ 103.221256] do_el0_svc+0x24/0x38
[ 103.224598] el0_svc+0x48/0x128
[ 103.227766] el0t_64_sync_handler+0x10c/0x138
[ 103.232150] el0t_64_sync+0x1a4/0x1a8
[ 103.235841] irq event stamp: 7936
[ 103.239173] hardirqs last enabled at (7935): [<ffff8000800aaf78>]
finish_task_switch.isra.0+0xb0/0x2a0
[ 103.248600] hardirqs last disabled at (7936): [<ffff800080eaac74>]
el1_dbg+0x24/0x90
[ 103.256369] softirqs last enabled at (7930): [<ffff800080066f98>]
handle_softirqs+0x4a0/0x4c0
[ 103.265007] softirqs last disabled at (7905): [<ffff800080010224>]
__do_softirq+0x1c/0x28
[ 103.273211] ---[ end trace 0000000000000000 ]---
Tomi
