Re: [PATCH v9 3/6] drm/i915: Add support for DRRS to switch RR

[Vandana Kannan <vandana.kannan@intel.com>]

On Apr-11-2014 2:56 PM, Daniel Vetter wrote:
> On Fri, Apr 11, 2014 at 02:48:53PM +0530, Vandana Kannan wrote:
>> On Apr-10-2014 2:28 PM, Daniel Vetter wrote:
>>> On Thu, Apr 10, 2014 at 11:43:15AM +0300, Jani Nikula wrote:
>>>>
>>>> Reviewed-by: Jani Nikula <jani.nikula@intel.com>
>>>>
>>>>
>>>> On Sat, 05 Apr 2014, Vandana Kannan <vandana.kannan@intel.com> wrote:
>>>>> From: Pradeep Bhat <pradeep.bhat@intel.com>
>>>>>
>>>>> This patch computes and stored 2nd M/N/TU for switching to different
>>>>> refresh rate dynamically. PIPECONF_EDP_RR_MODE_SWITCH bit helps toggle
>>>>> between alternate refresh rates programmed in 2nd M/N/TU registers.
>>>>>
>>>>> v2: Daniel's review comments
>>>>> Computing M2/N2 in compute_config and storing it in crtc_config
>>>>>
>>>>> v3: Modified reference to edp_downclock and edp_downclock_avail based on the
>>>>> changes made to move them from dev_private to intel_panel.
>>>>>
>>>>> v4: Modified references to is_drrs_supported based on the changes made to
>>>>> rename it to drrs_support.
>>>>>
>>>>> v5: Jani's review comments
>>>>> Removed superfluous return statements. Changed support for Gen 7 and above.
>>>>> Corrected indentation. Re-structured the code which finds crtc and connector
>>>>> from encoder. Changed some logs to be less verbose.
>>>>>
>>>>> v6: Modifying i915_drrs to include only intel connector as intel_dp can be
>>>>> derived from intel connector when required.
>>>>>
>>>>> v7: As per internal review comments, acquiring mutex just before accessing
>>>>> drrs RR. As per Chris's review comments, added documentation about the use
>>>>> of locking in the function.
>>>>>
>>>>> v8: Incorporated Jani's review comments.
>>>>> Removed reference to edp_downclock.
>>>>>
>>>>> v9: Jani's review comments. Modified comment in set_drrs. Changed index to
>>>>> type edp_drrs_refresh_rate_type. Check if PSR is enabled before setting
>>>>> registers fo DRRS.
>>>>>
>>>>> Signed-off-by: Pradeep Bhat <pradeep.bhat@intel.com>
>>>>> Signed-off-by: Vandana Kannan <vandana.kannan@intel.com>
>>>>> Cc: Jani Nikula <jani.nikula@linux.intel.com>
>>>
>>> Queued for -next, thanks for the patch. One thing that's missing though is
>>> the state readout and cross-check support for this new bit of crtc->config
>>> data. We need to add that before putting this to real use.
>>> -Daniel
>>>
>> Hi Daniel,
>>
>> Could you please elaborate on your input above - on the missing code and
>> cross-checking for support part?
> 
> If you add new state to crtc->config then you need to add the relevan
> readout code for that state (see the code in check_crtc_state) and ofc
> also add it to intel_pipe_config_compare.
> 
> This is a debug feature of our driver to make sure we never lose track of
> things and thus far has been extremely helpful in catching issues early.
> -Daniel
> 
I have submitted a patch adding this piece of code. Please have a look..
http://lists.freedesktop.org/archives/intel-gfx/2014-April/043569.html

- Vandana