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Revert r336326.

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In testing on a Dell Latitude 7480, having ig4.ko loaded during a
suspend caused the system to hang.  It turns out that ig4iic_intr() was
being called after the device entered D3, and entered an infinite loop
because a read of the I2C status register returned all ones, causing us
to attempt to read a byte from the data buffer until one of the status
bits clears.  This occured because ig4iic_pci0 shares an interrupt with
the VGA device on this laptop, so ig4iic_intr() gets called even when
there is no work to do.  This is exactly the problem fixed by r342170,
which resolves the hang for me and allows suspend/resume to work with
ig4.ko loaded.  So, re-enable autoloading of ig4.ko in the hope that
r342170 resolves the problem universally.

Reviewed by:	gonzo
MFC after:	1 month (pending an MFC of r342170)
Differential Revision:	https://reviews.freebsd.org/D18587
This commit is contained in:
markj 2018-12-17 21:13:05 +00:00
parent 4eb45cfa55
commit b323388966
1 changed files with 2 additions and 4 deletions
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6
sys/dev/ichiic/ig4_pci.c
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@ -232,7 +232,5 @@ DRIVER_MODULE_ORDERED(ig4iic_pci, pci, ig4iic_pci_driver, ig4iic_pci_devclass, 0
MODULE_DEPEND(ig4iic_pci, pci, 1, 1, 1);
MODULE_DEPEND(ig4iic_pci, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
MODULE_VERSION(ig4iic_pci, 1);
/*
* Loading this module breaks suspend/resume on laptops
* Do not add MODULE_PNP_INFO until it's impleneted
*/
MODULE_PNP_INFO("W32:vendor/device", pci, ig4iic_pci, ig4iic_pci_devices,
sizeof(ig4iic_pci_devices[0]), nitems(ig4iic_pci_devices));