+70
−49
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drm/i915: fix Haswell FDI link training code
This commit makes hsw_fdi_link_train responsible for implementing
everything described in the "Enable and train FDI" section from the
Hawell CRT mode set sequence documentation. We completely rewrite
hsw_fdi_link_train to match the documentation and we also call it in
the right place.
This patch was initially sent as a series of tiny patches fixing every
little problem of the function, but since there were too many patches
fixing the same function it got a little difficult to get the "big
picture" of how the function would be in the end, so here we amended
all the patches into a single big patch fixing the whole function.
Problems we fixed:
1 - Train Haswell FDI at the right time.
We need to train the FDI before enabling the pipes and planes, so
we're moving the call from lpt_pch_enable to haswell_crtc_enable
directly.
We are also removing ironlake_fdi_pll_enable since the PLL
enablement on Haswell is completely different and is also done
during the link training steps.
2 - Use the right FDI_RX_CTL register on Haswell
There is only one PCH transcoder, so it's always _FDI_RXA_CTL.
Using "pipe" here is wrong.
3 - Don't rely on DDI_BUF_CTL previous values
Just set the bits we want, everything else is zero. Also
POSTING_READ the register before sleeping.
4 - Program the FDI RX TUSIZE register on hsw_fdi_link_train
According to the mode set sequence documentation, this is the
right place. According to the FDI_RX_TUSIZE register description,
this is the value we should set.
Also remove the code that sets this register from the old
location: lpt_pch_enable.
5 - Properly program FDI_RX_MISC pwrdn lane values on HSW
6 - Wait only 35us for the FDI link training
First we wait 30us for the FDI receiver lane calibration, then we
wait 5us for the FDI auto training time.
7 - Remove an useless indentation level on hsw_fdi_link_train
We already "break" when the link training succeeds.
8 - Disable FDI_RX_ENABLE, not FDI_RX_PLL_ENABLE
When we fail the training.
9 - Change Haswell FDI link training error messages
We shouldn't call DRM_ERROR when still looping through voltage
levels since this is expected and not really a failure. So in this
commit we adjust the error path to only DRM_ERROR when we really
fail after trying everything.
While at it, replace DRM_DEBUG_DRIVER with DRM_DEBUG_KMS since
it's what we use everywhere.
10 - Try each voltage twice at hsw_fdi_link_train
Now with Daniel Vetter's suggestion to use "/2" instead of ">>1".
Signed-off-by: 
Paulo Zanoni <paulo.r.zanoni@intel.com>
[danvet: Applied tiny bikesheds:
- mention in comment that we test each voltage/emphasis level twice
- realing arguments of the only untouched reg write, it spilled over
the 80 char limit ...]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>