Hi Bryan,

Thank you for the patch.

On Tue, Aug 22, 2023 at 09:06:20PM +0100, Bryan O'Donoghue wrote:

Right now it is possible to do a vfe_get() with the internal reference count at 1. If vfe_check_clock_rates() returns non-zero then we will leave the reference count as-is and

run:

• pm_runtime_put_sync()
• vfe->ops->pm_domain_off()

skip:

• camss_disable_clocks()

Subsequent vfe_put() calls will when the ref-count is non-zero unconditionally run:

• pm_runtime_put_sync()
• vfe->ops->pm_domain_off()
• camss_disable_clocks()

vfe_get() should not attempt to roll-back on error when the ref-count is non-zero as the upper layers will still do their own vfe_put() operations.

vfe_put() will drop the reference count and do the necessary power domain release, the cleanup jumps in vfe_get() should only be run when the ref-count is zero.

[ 50.095796] CPU: 7 PID: 3075 Comm: cam Not tainted 6.3.2+ #80 [ 50.095798] Hardware name: LENOVO 21BXCTO1WW/21BXCTO1WW, BIOS N3HET82W (1.54 ) 05/26/2023 [ 50.095799] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 50.095802] pc : refcount_warn_saturate+0xf4/0x148 [ 50.095804] lr : refcount_warn_saturate+0xf4/0x148 [ 50.095805] sp : ffff80000c7cb8b0 [ 50.095806] x29: ffff80000c7cb8b0 x28: ffff16ecc0e3fc10 x27: 0000000000000000 [ 50.095810] x26: 0000000000000000 x25: 0000000000020802 x24: 0000000000000000 [ 50.095813] x23: ffff16ecc7360640 x22: 00000000ffffffff x21: 0000000000000005 [ 50.095815] x20: ffff16ed175f4400 x19: ffffb4d9852942a8 x18: ffffffffffffffff [ 50.095818] x17: ffffb4d9852d4a48 x16: ffffb4d983da5db8 x15: ffff80000c7cb320 [ 50.095821] x14: 0000000000000001 x13: 2e656572662d7265 x12: 7466612d65737520 [ 50.095823] x11: 00000000ffffefff x10: ffffb4d9850cebf0 x9 : ffffb4d9835cf954 [ 50.095826] x8 : 0000000000017fe8 x7 : c0000000ffffefff x6 : 0000000000057fa8 [ 50.095829] x5 : ffff16f813fe3d08 x4 : 0000000000000000 x3 : ffff621e8f4d2000 [ 50.095832] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff16ed32119040 [ 50.095835] Call trace: [ 50.095836] refcount_warn_saturate+0xf4/0x148 [ 50.095838] device_link_put_kref+0x84/0xc8 [ 50.095843] device_link_del+0x38/0x58 [ 50.095846] vfe_pm_domain_off+0x3c/0x50 [qcom_camss] [ 50.095860] vfe_put+0x114/0x140 [qcom_camss] [ 50.095869] csid_set_power+0x2c8/0x408 [qcom_camss] [ 50.095878] pipeline_pm_power_one+0x164/0x170 [videodev] [ 50.095896] pipeline_pm_power+0xc4/0x110 [videodev] [ 50.095909] v4l2_pipeline_pm_use+0x5c/0xa0 [videodev] [ 50.095923] v4l2_pipeline_pm_get+0x1c/0x30 [videodev] [ 50.095937] video_open+0x7c/0x100 [qcom_camss] [ 50.095945] v4l2_open+0x84/0x130 [videodev] [ 50.095960] chrdev_open+0xc8/0x250 [ 50.095964] do_dentry_open+0x1bc/0x498 [ 50.095966] vfs_open+0x34/0x40 [ 50.095968] path_openat+0xb44/0xf20 [ 50.095971] do_filp_open+0xa4/0x160 [ 50.095974] do_sys_openat2+0xc8/0x188 [ 50.095975] __arm64_sys_openat+0x6c/0xb8 [ 50.095977] invoke_syscall+0x50/0x128 [ 50.095982] el0_svc_common.constprop.0+0x4c/0x100 [ 50.095985] do_el0_svc+0x40/0xa8 [ 50.095988] el0_svc+0x2c/0x88 [ 50.095991] el0t_64_sync_handler+0xf4/0x120 [ 50.095994] el0t_64_sync+0x190/0x198 [ 50.095996] ---[ end trace 0000000000000000 ]---

Fixes: 779096916dae ("media: camss: vfe: Fix runtime PM imbalance on error") Cc: stable@vger.kernel.org Signed-off-by: Bryan O'Donoghue bryan.odonoghue@linaro.org

Reviewed-by: Laurent Pinchart laurent.pinchart@ideasonboard.com

---

drivers/media/platform/qcom/camss/camss-vfe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/platform/qcom/camss/camss-vfe.c b/drivers/media/platform/qcom/camss/camss-vfe.c index dabfd613b2f94..938f373bcd1fd 100644 --- a/drivers/media/platform/qcom/camss/camss-vfe.c +++ b/drivers/media/platform/qcom/camss/camss-vfe.c @@ -611,7 +611,7 @@ int vfe_get(struct vfe_device *vfe) } else { ret = vfe_check_clock_rates(vfe); if (ret < 0)

• 	goto error_pm_runtime_get;
  

• 	goto error_pm_domain;
  

  } vfe->power_count++;