[Intel-gfx] [PATCH 0/8] Allow Package C8+

[Paulo Zanoni]

From: Paulo Zanoni <paulo.r.zanoni at intel.com>

Hi

Some time ago I sent the first versions of patches to allow PC8+ and received
some feedback from Daniel. Based on his feedback and subsequent conversations,
we agreed that the right way to go would be to modify our "irq_uninstall"
function so it would allow uninstalling "everything but PCH HPD and master".
Then when we allow PC8+ we'd call the modified irq_uninstall, and then when we
disallow PC8+ we'call irq_postinstall.

So I started studying our interrupt code and noticed that if we wanted to allow
irq_uninstall/irq_postinstall multiple times on our code we'd have to change a
lot of stuff. So I wrote that code and also fixed other issues I also
identified. Some of these patches were already sent to the mailing list (and
even merged), but the part that allows us to call irq_uninstall+irq_postinstall
multiple times was not sent to the list yet.

In the end I felt unhappy with the resulting code: it looked ugly and still
didn't look bullet-proof (disable_irq is not cool). So I had a new idea: instead
of completely disabling the interrupts I decided to only disable the IMR
registers. We already touch the IMR registers everywhere on our code and avoid
the save/restore procedures on the IRQ handlers, so it should be safe to deal
with them. I added a small save/restore procedure for the IMR registers and
also added some WARNs that will tell us in case anybody tries to touch those
registers while PC8 is allowed. Even if we're still using a small register
save/restore file, I think this solution is much cleaner than the original patch
I proposed, so maybe Daniel thinks it's acceptable.

A small notice about the regfile: if you take a close look you'll see that we
also save/restore GTIER. This is because the GTIER register is reset when we
enter PC8. It should be safe to save/restore GTIER since it's only written at
our preinstall/postinstall/uninstall functions.

Patch 3 is the big patch which you should take a look. I couldn't find a nice
way to break it into more patches without writing patches that would just add
static functions that no one calls. It's probably easier to review this patch as
a whole than to review each piece of the puzzle in separate. But I'm open to
suggestions here. The other patches are very small and self-explanatory.

Notice that I won't just discard all the IRQ cleanups I already wrote, I will
still send them. I will just skip the ugly controversial patches that were only
useful for the PC8 work.

Thanks,
Paulo


Paulo Zanoni (8):
  drm/i915: add the FCLK case to intel_ddi_get_cdclk_freq
  drm/i915: don't disable/reenable IVB error interrupts when not needed
  drm/i915: allow package C8+ states on Haswell (disabled)
  drm/i915: avoid waking up from PC8 on DP AUX operations
  drm/i915: avoid waking up from PC8 on GMBUS operations
  drm/i915: silence message about the DDI buffers
  drm/i915: add i915_pc8_status debugfs file
  drm/i915: allow Package C8+ by default

 drivers/gpu/drm/i915/i915_debugfs.c  |  21 +++++++
 drivers/gpu/drm/i915/i915_dma.c      |   4 ++
 drivers/gpu/drm/i915/i915_drv.c      |   4 ++
 drivers/gpu/drm/i915/i915_drv.h      |  23 +++++++
 drivers/gpu/drm/i915/i915_irq.c      |  73 ++++++++++++++++++++++-
 drivers/gpu/drm/i915/intel_ddi.c     |  13 ++--
 drivers/gpu/drm/i915/intel_display.c | 112 +++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_dp.c      |  25 +++++++-
 drivers/gpu/drm/i915/intel_drv.h     |   6 ++
 drivers/gpu/drm/i915/intel_i2c.c     |  73 ++++++++++++++++-------
 drivers/gpu/drm/i915/intel_pm.c      |  15 +++++
 11 files changed, 336 insertions(+), 33 deletions(-)

-- 
1.8.1.2