On Wed, Jan 08, 2025 at 01:13:41AM +0200, Sergey Ryazanov wrote: > On 05.01.2025 19:39, Maciej S. Szmigiero wrote: > > Currently, the driver is seriously broken with respect to the > > hibernation (S4): after image restore the device is back into > > IPC_MEM_EXEC_STAGE_BOOT (which AFAIK means bootloader stage) and needs > > full re-launch of the rest of its firmware, but the driver restore > > handler treats the device as merely sleeping and just sends it a > > wake-up command. > > > > This wake-up command times out but device nodes (/dev/wwan*) remain > > accessible. > > However attempting to use them causes the bootloader to crash and > > enter IPC_MEM_EXEC_STAGE_CD_READY stage (which apparently means "a crash > > dump is ready"). > > > > It seems that the device cannot be re-initialized from this crashed > > stage without toggling some reset pin (on my test platform that's > > apparently what the device _RST ACPI method does). > > > > While it would theoretically be possible to rewrite the driver to tear > > down the whole MUX / IPC layers on hibernation (so the bootloader does > > not crash from improper access) and then re-launch the device on > > restore this would require significant refactoring of the driver > > (believe me, I've tried), since there are quite a few assumptions > > hard-coded in the driver about the device never being partially > > de-initialized (like channels other than devlink cannot be closed, > > for example). > > Probably this would also need some programming guide for this hardware. > > > > Considering that the driver seems orphaned [1] and other people are > > hitting this issue too [2] fix it by simply unbinding the PCI driver > > before hibernation and re-binding it after restore, much like > > USB_QUIRK_RESET_RESUME does for USB devices that exhibit a similar > > problem. > > > > Tested on XMM7360 in HP EliteBook 855 G7 both with s2idle (which uses > > the existing suspend / resume handlers) and S4 (which uses the new code). > > > > [1]: https://lore.kernel.org/all/c248f0b4-2114-4c61-905f-466a786bdebb@xxxxxxxxxxxxx/ > > [2]: > > https://github.com/xmm7360/xmm7360-pci/issues/211#issuecomment-1804139413 > > > > Signed-off-by: Maciej S. Szmigiero <mail@xxxxxxxxxxxxxxxxxxxxx> > > Generally looks good to me. Lets wait for approval from PCI maintainers to > be sure that there no unexpected side effects. I have nothing useful to contribute here. Seems like kind of a mess. But Intel claims to maintain this, so it would be nice if they would step up and make this work nicely. Bjorn
