<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_REOPENED " title="REOPENED - [snb] backlight issue on TOSHIBA PORTEGE R830 after suspend/resume" href="https://bugs.freedesktop.org/show_bug.cgi?id=82634#c33">Comment # 33</a> on <a class="bz_bug_link bz_status_REOPENED " title="REOPENED - [snb] backlight issue on TOSHIBA PORTEGE R830 after suspend/resume" href="https://bugs.freedesktop.org/show_bug.cgi?id=82634">bug 82634</a> from <a class="email" href="mailto:aaron.lu@intel.com" title="Aaron Lu <aaron.lu@intel.com>"> Aaron Lu</a> <pre>The acpidump shows that _BCM makes use of SMM code to do the backlight handling by writing some values to some fixed memory address and then write a value to IO port 0xB2: _BCM -> SMBR -> BIOT(arg0, arg1, ..., arg6) Method (BIOT, 7, Serialized) { IEAX = Arg0 IEBX = Arg1 IECX = Arg2 IEDX = Arg3 IESI = Arg4 IEDI = Arg5 SSMP = Arg6 } The IEXX are fields defined in an operation region of memory type and from their names, they seem to be meant to pass their values to the corresponding registers. And SSMP is defined as: OperationRegion (SPRT, SystemIO, 0xB2, 0x02) Field (SPRT, ByteAcc, Lock, Preserve) { SSMP, 8 } And the final write to it should trigger SMI. The SMM code may do something magical and I have no idea what would happen there. Sylvain also said that a LID status change could bring up the backlight, I suspect that has something to do with intel_lid_notify, perhaps this function bring up the backlight? Sylvain, I'll attach a test patch to disable the register of intel_lid_notify and then please test if open/close the LID, you can still turn the backlight on, thanks. You may get a black screen with this test patch, please prepare for that. If the result is no, then perhaps that means intel_lid_notify has the knowledge of turning the backlight on and we should use that somewhere in i915 driver to turn on the backlight during resume?</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> <li>You are on the CC list for the bug.</li> <li>You are the assignee for the bug.</li> </ul> </body> </html>