On Mon, Sep 23, 2024 at 08:40:07AM +0530, Suraj Kandpal wrote: > Reduce SHPD_CNT to 250us for display version 12 as it lines up > with DP1.4a(Table3-4) spec. > > --v2 > -Update commit message and comment [Matt] > > Signed-off-by: Suraj Kandpal <suraj.kandpal@xxxxxxxxx> > --- > drivers/gpu/drm/i915/display/intel_hotplug_irq.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_hotplug_irq.c b/drivers/gpu/drm/i915/display/intel_hotplug_irq.c > index 2c4e946d5575..8427386132e6 100644 > --- a/drivers/gpu/drm/i915/display/intel_hotplug_irq.c > +++ b/drivers/gpu/drm/i915/display/intel_hotplug_irq.c > @@ -849,7 +849,11 @@ static void icp_hpd_irq_setup(struct drm_i915_private *dev_priv) > enabled_irqs = intel_hpd_enabled_irqs(dev_priv, dev_priv->display.hotplug.pch_hpd); > hotplug_irqs = intel_hpd_hotplug_irqs(dev_priv, dev_priv->display.hotplug.pch_hpd); > > - if (INTEL_PCH_TYPE(dev_priv) <= PCH_TGP) > + /* > + * We reduce the value to 250us to be able to detect SHPD when an external display > + * is connected. This is also expected of us as stated in DP1.4a Table 3-4. > + */ > + if (INTEL_PCH_TYPE(dev_priv) < PCH_TGP) > intel_uncore_write(&dev_priv->uncore, SHPD_FILTER_CNT, SHPD_FILTER_CNT_500_ADJ); > else > intel_uncore_write(&dev_priv->uncore, SHPD_FILTER_CNT, SHPD_FILTER_CNT_250); IMO if we start reducing this for older platforms then we should just do it for all of them, instead of based on some random cutoff. -- Ville Syrjälä Intel
