On Fri, Aug 19, 2016 at 05:45:03PM +0100, Chris Wilson wrote: > Some GMBUS devices fail to report NAKs (even recent Skylakes), resulting > in us hitting the 50ms timeout every time we try to read an EDID on a > disconnected device. Try a quick GPIO discovery first by setting the > clock line and seeing if the device responds.
Sadly doesn't work. Doesn't make a difference on the problematic port (HDMI-A-2 on a ThinkPad 13) -- still very slow, nor on the non-problematic port (HDMI-A-1 on the same laptop) -- still fast, but seems to make things a lot worse on HDMI-A-1 when there *is* a display connected -- incredibly slow. So, ironically I'd say NAK to the NAK-patch. Kind regards, David Weinehall > Signed-off-by: Chris Wilson <[email protected]> > Cc: David Weinehall <[email protected]> > --- > drivers/gpu/drm/i915/intel_i2c.c | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/drivers/gpu/drm/i915/intel_i2c.c > b/drivers/gpu/drm/i915/intel_i2c.c > index 6841c41281a3..72945a7c5547 100644 > --- a/drivers/gpu/drm/i915/intel_i2c.c > +++ b/drivers/gpu/drm/i915/intel_i2c.c > @@ -461,6 +461,22 @@ gmbus_xfer_index_read(struct drm_i915_private *dev_priv, > struct i2c_msg *msgs) > return ret; > } > > +static bool gpio_is_alive(struct intel_gmbus *bus) > +{ > + bool result = true; > + > + intel_i2c_quirk_set(bus->dev_priv, true); > + set_clock(bus, 1); > + > + if (wait_for_us(get_clock(bus), 10) && wait_for(get_clock(bus), 2)) > + result = false; > + > + set_clock(bus, 0); > + intel_i2c_quirk_set(bus->dev_priv, false); > + > + return result; > +} > + > static int > do_gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num) > { > @@ -474,6 +490,13 @@ do_gmbus_xfer(struct i2c_adapter *adapter, struct > i2c_msg *msgs, int num) > int i = 0, inc, try = 0; > int ret = 0; > > + /* Some GMBUS devices fail to report NAKs and so we hit the 50ms > + * timeout, every time. Try a quick GPIO discovery first by seeing > + * if the device responds to setting the clock line high. > + */ > + if (!gpio_is_alive(bus)) > + return -ENXIO; > + > intel_uncore_forcewake_get(dev_priv, fw); > retry: > I915_WRITE_FW(GMBUS0, bus->reg0); > -- > 2.9.3 > _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
