From: Imre Deak <imre.deak@intel.com>
To: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 6/7] drm/i915: Fix DP_TRAIN_MAX_{PRE_EMPHASIS, SWING}_REACHED handling
Date: Fri, 26 Jun 2020 00:06:52 +0300 [thread overview]
Message-ID: <20200625210652.GA18750@ideak-desk.fi.intel.com> (raw)
In-Reply-To: <20200512174145.3186-7-ville.syrjala@linux.intel.com>
On Tue, May 12, 2020 at 08:41:44PM +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> The DP spec says:
> "The transmitter shall support at least three levels of voltage
> swing (Levels 0, 1, and 2).
>
> If only three levels of voltage swing are supported (VOLTAGE
> SWING SET field (bits 1:0) are programmed to 10 (Level 2)),
> this bit shall be set to 1, and cleared in all other cases.
>
> If all four levels of voltage swing are supported (VOLTAGE
> SWING SET field (bits 1:0) are programmed to 11 (Level 3)),
> this bit shall be set to 1,and cleared in all other cases."
>
> Let's follow that exactly instead of the current apporach
> where we can set those also for vswing/preemph levels 0 or 1
> (or 2 when the platform max is 3).
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Yep, so the sink could've incorrectly stopped asking for higher vswing
levels after it asked for 0 vs+2 pe, when the max vs is 2 for instance.
Matches the spec:
Reviewed-by: Imre Deak <imre.deak@intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_dp_link_training.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> index 573f93779449..aa7af531bcb8 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> @@ -72,8 +72,9 @@ void intel_dp_get_adjust_train(struct intel_dp *intel_dp,
> if (p >= preemph_max)
> p = preemph_max | DP_TRAIN_MAX_PRE_EMPHASIS_REACHED;
>
> - voltage_max = min(intel_dp->voltage_max(intel_dp),
> - dp_voltage_max(p));
> + v = min(v, dp_voltage_max(p));
> +
> + voltage_max = intel_dp->voltage_max(intel_dp);
> if (v >= voltage_max)
> v = voltage_max | DP_TRAIN_MAX_SWING_REACHED;
>
> --
> 2.26.2
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
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next prev parent reply other threads:[~2020-06-25 21:07 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-12 17:41 [Intel-gfx] [PATCH 0/7] drm/i915: DP vswing/preemph fixes Ville Syrjala
2020-05-12 17:41 ` [Intel-gfx] [PATCH 1/7] drm/i915: Fix cpt/ppt max pre-emphasis Ville Syrjala
2020-05-30 1:30 ` Souza, Jose
2020-05-12 17:41 ` [Intel-gfx] [PATCH 2/7] drm/i915: Fix ibx max vswing/preemph Ville Syrjala
2020-06-01 20:23 ` Souza, Jose
2020-05-12 17:41 ` [Intel-gfx] [PATCH 3/7] drm/i915: Fix ivb cpu edp vswing Ville Syrjala
2020-05-30 1:38 ` Souza, Jose
2020-05-12 17:41 ` [Intel-gfx] [PATCH 4/7] drm/i915: Add {preemph, voltage}_max() vfuncs Ville Syrjala
2020-05-15 19:09 ` Manasi Navare
2020-05-12 17:41 ` [Intel-gfx] [PATCH 5/7] drm/i915: Reverse preemph vs. voltage swing preference Ville Syrjala
2020-05-15 19:18 ` Manasi Navare
2020-05-15 19:59 ` Ville Syrjälä
2020-05-18 18:20 ` Manasi Navare
2020-05-12 17:41 ` [Intel-gfx] [PATCH 6/7] drm/i915: Fix DP_TRAIN_MAX_{PRE_EMPHASIS, SWING}_REACHED handling Ville Syrjala
2020-06-25 21:06 ` Imre Deak [this message]
2020-05-12 17:41 ` [Intel-gfx] [PATCH 7/7] drm/i915: Replace some hand rolled max()s Ville Syrjala
2020-05-15 19:21 ` Manasi Navare
2020-05-12 18:38 ` [Intel-gfx] ✓ Fi.CI.BAT: success for drm/i915: DP vswing/preemph fixes Patchwork
2020-05-12 20:11 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork
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