On Mon, Sep 23, 2024 at 08:38:35PM +0300, Ville Syrjälä wrote: > 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. The other things we might want to think about are moving this into *_hpd_detection_setup() instead, and perhaps we should also start explicitly configuring SHPD_PULSE_CNT as well? -- Ville Syrjälä Intel
