[PATCH 0/9] drm/i915/intel_i2c: fix gmbus writes and related issues

Daniel Kurtz djkurtz at chromium.org
Wed Mar 7 03:50:41 PST 2012

This patchset addresses a couple of issues with the i915 gmbus implementation:
  * fixes misassigned pin port pair for HDMI-D
  * fixes write transactions when they are the only transaction requested
    (including large >4-byte writes)
  * returns -ENXIO and -ETIMEDOUT as appropriate so upper layers can handled
    i2c transaction failures
  * optimizes the typical read transaction case by using the INDEX cycle

The patchset should apply cleanly onto linus/master.
It is inspired by, but completely supercedes, a similar patch submitted
recently by Benson Leung (bleung at chromium.org).
I'd be happy to rebase on a different tree if necessary.

There is one more patch in the set which I have not included here.  It enables
the PCH GMBUS interrupt and makes use of it to eliminate the very slow
'wait_for' polling loop.  This patch was not included, however, because there
is at least one case I have discovered where the i915 driver issues a GMBUS
transaction AFTER its interrupts have been initialized, but BEFORE it they have
been enabled.  Both the gmbus transaction and irq initialization occur during
i915_load_modeset_init(), but the gmbus transaction happens first, during:
Is there a way to switch the order of these to events?
Or does it make more sense for the gmbus driver to check a "bool irq_enabled",
and choose whether to poll or use the GMBUS interrupt?
... or both?

Daniel Kurtz (9):
  drm/i915/intel_i2c: cleanup
  drm/i915/intel_i2c: assign HDMI port D to pin pair 6
  drm/i915/intel_i2c: refactor using intel_gmbus_get_bus
  drm/i915/intel_i2c: cleanup gmbus/gpio pin assignments
  drm/i915/intel_i2c: add locking around i2c algorithm accesses
  drm/i915/intel_i2c: return -ENXIO for device NAK
  drm/i915/intel_i2c: use WAIT cycle, not STOP
  drm/i915/intel_i2c: use INDEX cycles for i2c read transactions
  drm/i915/intel_i2c: reuse GMBUS2 value read in polling loop

 drivers/gpu/drm/i915/i915_drv.h    |    5 +-
 drivers/gpu/drm/i915/i915_reg.h    |    5 +-
 drivers/gpu/drm/i915/intel_bios.c  |   10 ++-
 drivers/gpu/drm/i915/intel_crt.c   |   13 ++--
 drivers/gpu/drm/i915/intel_drv.h   |    3 +-
 drivers/gpu/drm/i915/intel_dvo.c   |    4 +-
 drivers/gpu/drm/i915/intel_hdmi.c  |   29 +++---
 drivers/gpu/drm/i915/intel_i2c.c   |  175 +++++++++++++++++++++++++-----------
 drivers/gpu/drm/i915/intel_lvds.c  |    2 +-
 drivers/gpu/drm/i915/intel_modes.c |    6 +-
 drivers/gpu/drm/i915/intel_sdvo.c  |   10 +--
 11 files changed, 165 insertions(+), 97 deletions(-)


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