[Saucy][SRU][PATCH 1/1] (no-up) Revert "Revert "drm/i915: revert eDP bpp clamping code changes""

[Robert Hooker]

On Thu, Oct 31, 2013 at 12:03 PM, Joseph Salisbury
<joseph.salisbury at canonical.com> wrote:
> On 10/24/2013 06:22 PM, Tim Gardner wrote:
>> On 10/16/2013 02:06 PM, Joseph Salisbury wrote:
>>> On 10/16/2013 04:57 PM, Joseph Salisbury wrote:
>>>> BugLink: http://bugs.launchpad.net/bugs/1195483
>>>>
>>>> This reverts commit 657445fe8660100ad174600ebfa61536392b7624.
>>>>
>>>> Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
>>>> ---
>>>>   drivers/gpu/drm/i915/intel_dp.c |   18 ++++++++++++++----
>>>>   1 file changed, 14 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/intel_dp.c
>>>> b/drivers/gpu/drm/i915/intel_dp.c
>>>> index 26e162b..ce933ad 100644
>>>> --- a/drivers/gpu/drm/i915/intel_dp.c
>>>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>>>> @@ -709,10 +709,7 @@ intel_dp_compute_config(struct intel_encoder
>>>> *encoder,
>>>>
>>>>       /* Walk through all bpp values. Luckily they're all nicely
>>>> spaced with 2
>>>>        * bpc in between. */
>>>> -    bpp = pipe_config->pipe_bpp;
>>>> -    if (is_edp(intel_dp) && dev_priv->vbt.edp_bpp)
>>>> -        bpp = min_t(int, bpp, dev_priv->vbt.edp_bpp);
>>>> -
>>>> +    bpp = min_t(int, 8*3, pipe_config->pipe_bpp);
>>>>       for (; bpp >= 6*3; bpp -= 2*3) {
>>>>           mode_rate = intel_dp_link_required(adjusted_mode->clock,
>>>> bpp);
>>>>
>>>> @@ -763,6 +760,19 @@ found:
>>>>                      &pipe_config->dp_m_n);
>>>>
>>>>       intel_dp_set_clock(encoder, pipe_config, intel_dp->link_bw);
>>>> +    /*
>>>> +     * XXX: We have a strange regression where using the vbt edp
>>>> bpp value
>>>> +     * for the link bw computation results in black screens, the
>>>> panel only
>>>> +     * works when we do the computation at the usual 24bpp (but still
>>>> +     * requires us to use 18bpp). Until that's fully debugged, stay
>>>> +     * bug-for-bug compatible with the old code.
>>>> +     */
>>>> +    if (is_edp(intel_dp) && dev_priv->vbt.edp_bpp) {
>>>> +        DRM_DEBUG_KMS("clamping display bpc (was %d) to eDP (%d)\n",
>>>> +                  bpp, dev_priv->vbt.edp_bpp);
>>>> +        bpp = min_t(int, bpp, dev_priv->vbt.edp_bpp);
>>>> +    }
>>>> +    pipe_config->pipe_bpp = bpp;
>>>>
>>>>       return true;
>>>>   }
>>>
>>> A proper fix is also being discussed upstream:
>>> https://bugzilla.kernel.org/show_bug.cgi?id=59841
>>>
>>> Maybe an alternative to this patch is to add something to the Saucy
>>> release notes until this is fixed upstream?
>>>
>>>
>>
>> Joe - any upstream movement on this ?
>>
> A fix is avaiable upstream and also cc'd to stable:
>
> commit c6cd2ee2d59111a07cd9199564c9bdcb2d11e5cf
> Author: Jani Nikula <jani.nikula at intel.com>
> Date:   Mon Oct 21 10:52:07 2013 +0300
>
>     drm/i915/dp: workaround BIOS eDP bpp clamping issue
>
> and a couple of dependencies are now in Linus' tree, i.e. should be
> released in 3.12. The commits are also CC: stable.
>
>
> --
> kernel-team mailing list
> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team


commit 7195a50b5c7e00cc3312934fd022c3006b533d12
Author: Ville Syrjälä <ville.syrjala at linux.intel.com>
Date:   Tue Sep 24 14:24:05 2013 +0300

    drm/i915: Add HSW CRT output readout support

commit 4f56d12ebb28fceac4c6e60c8993fbfc122e1399
Author: Ville Syrjälä <ville.syrjala at linux.intel.com>
Date:   Mon Oct 21 10:52:06 2013 +0300

    drm/i915: Add support for pipe_bpp readout

are the required extra commits according to the mailing list thread.