Commit 0d95e11b authored Mar 31, 2014 by Ville Syrjälä Committed by Daniel Vetter Apr 03, 2014

drm/i915: Warn when DPIO read returns 0xffffffff



DPIO reads from groups/broadcast register offsets for PCS and
TX return all 1's. If that result gets used for something
we'll probably end up doing something wrong. So warn when that
happens.

FIXME there might be some registers where all 1's is a valid value,
so ideally we should check the register offset instead...

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
[danvet: copypaste the FIXME comment into the code.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

parent 2070f00c

drivers/gpu/drm/i915/intel_sideband.c

+8 −0

Original line number	Original line	Diff line number	Diff line
	@@ -182,6 +182,14 @@ u32 vlv_dpio_read(struct drm_i915_private *dev_priv, enum pipe pipe, int reg)

	vlv_sideband_rw(dev_priv, DPIO_DEVFN, DPIO_PHY_IOSF_PORT(DPIO_PHY(pipe)),		vlv_sideband_rw(dev_priv, DPIO_DEVFN, DPIO_PHY_IOSF_PORT(DPIO_PHY(pipe)),
	DPIO_OPCODE_REG_READ, reg, &val);		DPIO_OPCODE_REG_READ, reg, &val);

			/*
			* FIXME: There might be some registers where all 1's is a valid value,
			* so ideally we should check the register offset instead...
			*/
			WARN(val == 0xffffffff, "DPIO read pipe %c reg 0x%x == 0x%x\n",
			pipe_name(pipe), reg, val);

	return val;		return val;
	}		}