From: Ville Syrjälä Date: Mon, 31 Mar 2014 15:21:27 +0000 (+0300) Subject: drm/i915: Warn when DPIO read returns 0xffffffff X-Git-Tag: next-20140428~44^2~89 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=0d95e11b7e27536dbb52c42a8bb5a6f31d7c24cf;p=karo-tx-linux.git 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 Reviewed-by: Jesse Barnes [danvet: copypaste the FIXME comment into the code.] Signed-off-by: Daniel Vetter --- diff --git a/drivers/gpu/drm/i915/intel_sideband.c b/drivers/gpu/drm/i915/intel_sideband.c index 0954f132726e..b1a5514e695a 100644 --- a/drivers/gpu/drm/i915/intel_sideband.c +++ b/drivers/gpu/drm/i915/intel_sideband.c @@ -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)), 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; }