I have a Lenovo X201 laptop with an i7-620M processor. After I resume from a Suspend to RAM the graphics are very slow. Suspend to Disk does not cause the same problem and doing a Suspend to Disk after a Suspend to RAM fixes the problem. According to Chris Wilson from the intel-gfx mailing list: "Known problem. The PAT lose the WC bits for the GTT aperture on resume. There is a workaround that we can do: recreate the ioremapping upon resume. (But the root cause is not a gfx driver bug.)"
As a test, I booted with the "nopat" option and the problem went away.
Created attachment 51332 [details] dmesg before suspend
Created attachment 51342 [details] dmesg from after resume
Created attachment 51352 [details] kernel_page_tables before suspend
Created attachment 51362 [details] kernel_page_tables after resume
Chris, could you please update this report to tell us which part of the kernel needs fixing? x86? AGP? Thanks.
If there are any helpful tests or diagnostics I can provide, just let me know.
commit 84ac7cdbdd0f04df6b96153f7a79127fd6e45467 Author: Suresh Siddha <suresh.b.siddha@intel.com> Date: Tue Mar 29 15:38:12 2011 -0700 x86, mtrr, pat: Fix one cpu getting out of sync during resume On laptops with core i5/i7, there were reports that after resume graphics workloads were performing poorly on a specific AP, while the other cpu's were ok. This was observed on a 32bit kernel specifically.