Why doesn't pm-suspend work repeatedly?

Question

linux

Samsung NP535 laptop with Debian 8 (netinstall), kernel 3.16.0-4-686-pae, openbox, video Radeon HD 7500G and 7550M (amdshny firewood). Installed pm-utils, the standby mode (which is without swap) has earned.
From the root I execute pm-suspend, the laptop goes into standby mode, it exits normally. But when pm-suspend is reactivated, the screen turns off for a second or two and does not go into standby mode, it continues to work if an integrated card is used. Everything is good on the disc.
pm-is-supported indicates that pm-suspend is supported. LMT installed. Previously, standby worked correctly on Ubuntu in all versions.
Tell me where to dig?
dmesg after being unable to sleep:

[  765.330357] PM: Syncing filesystems ... done.
[  765.401405] PM: Preparing system for mem sleep
[  766.803852] PM: Entering mem sleep
[  766.804079] Suspending console(s) (use no_console_suspend to debug)
[  766.804321] <3>[fglrx:fglrx_pci_suspend] *ERROR* fglrx_pci_suspend. Can not get drm device context .
[  766.804380] pci_legacy_suspend(): fglrx_pci_suspend+0x0/0x140 [fglrx] returns -5
[  766.804388] dpm_run_callback(): pci_pm_suspend+0x0/0x120 returns -5
[  766.804390] PM: Device 0000:01:00.0 failed to suspend async: error -5
[  766.816492] PM: Some devices failed to suspend, or early wake event detected
[  766.825468] PM: resume of devices complete after 8.964 msecs
[  766.825963] PM: Finishing wakeup.

Answer 1

fglrx is the video card driver.
According to the reports, the problem was due to an error when trying to call the fglrx_pci_suspend function, and as a result, the hibernation process was interrupted.
Try updating the driver.
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