[PATCH] drm/radeon: avoid turning off spread spectrum for used pll

[Jerome Glisse]

On Fri, Aug 17, 2012 at 2:54 PM, Alex Deucher <alexdeucher at gmail.com> wrote:
> On Fri, Aug 17, 2012 at 2:40 PM,  <j.glisse at gmail.com> wrote:
>> From: Jerome Glisse <jglisse at redhat.com>
>>
>> If spread spectrum is enabled and in use for a given pll we
>> should not turn it off as it will lead to turning off display
>> for crtc that use the pll (this behavior was observed on chelsea
>> edp).
>>
>> Signed-off-by: Jerome Glisse <jglisse at redhat.com>
>
> Looks good.  I think an alternative would be to just always enable SS
> for DP/eDP rather than checking the DPCD since all DP connections run
> on the same PLL.  IIRC, that's what the closed driver does.
>
> Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

Forgot cc stable

>
>> ---
>>  drivers/gpu/drm/radeon/atombios_crtc.c |   25 +++++++++++++++++++++----
>>  1 files changed, 21 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/radeon/atombios_crtc.c b/drivers/gpu/drm/radeon/atombios_crtc.c
>> index c6fcb5b..cb18813 100644
>> --- a/drivers/gpu/drm/radeon/atombios_crtc.c
>> +++ b/drivers/gpu/drm/radeon/atombios_crtc.c
>> @@ -444,11 +444,28 @@ union atom_enable_ss {
>>  static void atombios_crtc_program_ss(struct radeon_device *rdev,
>>                                      int enable,
>>                                      int pll_id,
>> +                                    int crtc_id,
>>                                      struct radeon_atom_ss *ss)
>>  {
>> +       unsigned i;
>>         int index = GetIndexIntoMasterTable(COMMAND, EnableSpreadSpectrumOnPPLL);
>>         union atom_enable_ss args;
>>
>> +       if (!enable) {
>> +               for (i = 0; i < 6; i++) {
>> +                       if (rdev->mode_info.crtcs[i] &&
>> +                           rdev->mode_info.crtcs[i]->enabled &&
>> +                           i != crtc_id &&
>> +                           pll_id == rdev->mode_info.crtcs[i]->pll_id) {
>> +                               /* one other crtc is using this pll don't turn
>> +                                * off spread spectrum as it might turn off
>> +                                * display on active crtc
>> +                                */
>> +                               return;
>> +                       }
>> +               }
>> +       }
>> +
>>         memset(&args, 0, sizeof(args));
>>
>>         if (ASIC_IS_DCE5(rdev)) {
>> @@ -1028,7 +1045,7 @@ static void atombios_crtc_set_pll(struct drm_crtc *crtc, struct drm_display_mode
>>                 radeon_compute_pll_legacy(pll, adjusted_clock, &pll_clock, &fb_div, &frac_fb_div,
>>                                           &ref_div, &post_div);
>>
>> -       atombios_crtc_program_ss(rdev, ATOM_DISABLE, radeon_crtc->pll_id, &ss);
>> +       atombios_crtc_program_ss(rdev, ATOM_DISABLE, radeon_crtc->pll_id, radeon_crtc->crtc_id, &ss);
>>
>>         atombios_crtc_program_pll(crtc, radeon_crtc->crtc_id, radeon_crtc->pll_id,
>>                                   encoder_mode, radeon_encoder->encoder_id, mode->clock,
>> @@ -1051,7 +1068,7 @@ static void atombios_crtc_set_pll(struct drm_crtc *crtc, struct drm_display_mode
>>                         ss.step = step_size;
>>                 }
>>
>> -               atombios_crtc_program_ss(rdev, ATOM_ENABLE, radeon_crtc->pll_id, &ss);
>> +               atombios_crtc_program_ss(rdev, ATOM_ENABLE, radeon_crtc->pll_id, radeon_crtc->crtc_id, &ss);
>>         }
>>  }
>>
>> @@ -1572,11 +1589,11 @@ void radeon_atom_disp_eng_pll_init(struct radeon_device *rdev)
>>                                                                    ASIC_INTERNAL_SS_ON_DCPLL,
>>                                                                    rdev->clock.default_dispclk);
>>                 if (ss_enabled)
>> -                       atombios_crtc_program_ss(rdev, ATOM_DISABLE, ATOM_DCPLL, &ss);
>> +                       atombios_crtc_program_ss(rdev, ATOM_DISABLE, ATOM_DCPLL, -1, &ss);
>>                 /* XXX: DCE5, make sure voltage, dispclk is high enough */
>>                 atombios_crtc_set_disp_eng_pll(rdev, rdev->clock.default_dispclk);
>>                 if (ss_enabled)
>> -                       atombios_crtc_program_ss(rdev, ATOM_ENABLE, ATOM_DCPLL, &ss);
>> +                       atombios_crtc_program_ss(rdev, ATOM_ENABLE, ATOM_DCPLL, -1, &ss);
>>         }
>>
>>  }
>> --
>> 1.7.1
>>
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