cdc-acm: fix incorrect runtime wakeup in acm_tty_write
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Patches in v3 No applies recorded yet
| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/3 | usb: add function usb_autopm_get_interface_upgradedrivers/ include/ | +57 | 0 replies | |
| 2/3 | cdc-acm: call usb_autopm_get_interface_upgrade in acm_tty_writedrivers/ | +6 | 0 replies | |
| 3/3 | n_gsm: wake up ldisc tty before using itdrivers/ | +39 | 0 replies |
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Cover letter [PATCH V3 0/3] cdc-acm: fix incorrect runtime wakeup in acm_tty_write
Resend as V1/V2 have email format issue. Sorry for bothering.
I use Thunderbird. It has no a button to enable LKML email simply. :)
V3: Change email config to resend.
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There is a scenario about cdc-acm utilization.Application opens n_gsm tty and cdc-acm tty. cdc-acm tty connects to xhci device. The application configures cdc-adm tty to n_gsm tty as ldisc tty.
n_gsm=>cdc-acm=>xhci driver
acm_tty_write can be called from n_gsm driver by ldisc connection, and from application when application opens cdc-acm tty directly. acm_tty_write wakes up the device by calling usb_autopm_get_interface_async, which calls pm_runtime_get. However, pm_runtime_get can't wake up the device before returning as it's an async wake up. Then, acm_tty_write might access the device when it is off.
The patchset fixes it by:
1) add a new function usb_autopm_get_interface_upgrade to deal with above 2 requirements;
2) wake up device in n_gsm driver if n_gsm drivers calls cdc-acm driver;