On Tue, 2017-02-28 at 18:57 -0800, Dhinakaran Pandiyan wrote:
> According to BSpec, "The CD clock frequency must be at least twice the
> frequency of the Azalia BCLK." and BCLK is configured to 96 MHz by
> default. BXT and GLK both have cdclk frequencies that are less han 192 MHz,
> so apply the check conditionally for these platforms.
>
> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandi...@intel.com>
> ---
> drivers/gpu/drm/i915/intel_cdclk.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_cdclk.c
> b/drivers/gpu/drm/i915/intel_cdclk.c
> index 8fc0f72..89027fa 100644
> --- a/drivers/gpu/drm/i915/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/intel_cdclk.c
> @@ -1444,6 +1444,8 @@ static int intel_min_cdclk(struct drm_atomic_state
> *state)
> struct intel_crtc_state *crtc_state;
>
> crtc_state = to_intel_crtc_state(cstate);
> + if (!crtc_state->has_audio)
> + continue;
>
> /* According to BSpec, "Do not use DisplayPort with CDCLK less
> * than 432 MHz, audio enabled, port width x4, and link rate
> @@ -1452,7 +1454,6 @@ static int intel_min_cdclk(struct drm_atomic_state
> *state)
> * for GLK is at 316.8 MHz
> */
> if (intel_crtc_has_dp_encoder(crtc_state) &&
> - crtc_state->has_audio &&
> crtc_state->port_clock >= 540000 &&
> crtc_state->lane_count == 4) {
> if (IS_GEMINILAKE(dev_priv))
> @@ -1460,6 +1461,13 @@ static int intel_min_cdclk(struct drm_atomic_state
> *state)
> else if (IS_BROADWELL(dev_priv) || IS_GEN9(dev_priv))
> min_cdclk = 432000;
> }
> +
> + /* According to BSpec, "The CD clock frequency must be at least
> + * twice the frequency of the Azalia BCLK." and BCLK is 96 MHz
> + * by default.
> + */
> + if (IS_BROXTON(dev_priv) || IS_GEMINILAKE(dev_priv))
> + min_cdclk = max(min_cdclk, 2 * 96000);
Hmm, my assumption from reviewing patch 1 of "this returns a valid cdclk" is
broken here. Maybe with the idea of splitting the calc_cdclk_state() in two from
my comment to Paulo's series this could be just:
min_cdclk = max(min_cdcdlk, choose_cdclk(2 * 96000));
?
On second thought, it does make sense for this kind of platform specific
restrictions to be dealt with in platform specific hook, so duplicating that in
calc_cdclk_state() is not that bad?
Ander
> }
>
> return min_cdclk;
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