diff mbox series

[2/2] drm/i915/hotplug: Add comment for DISPLAY13 SHPD_FILTER_CNT value

Message ID 20240917052307.760662-3-suraj.kandpal@intel.com (mailing list archive)
State New, archived
Headers show
Series Reduce SHPD_FILTER_CNT value | expand

Commit Message

Suraj Kandpal Sept. 17, 2024, 5:23 a.m. UTC
Add the reason for having SHPD_FILTER_CNT value for DISPLAY13 and
above as 250us instead of 500us.

Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
---
 drivers/gpu/drm/i915/display/intel_hotplug_irq.c | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Matt Roper Sept. 20, 2024, 9:33 p.m. UTC | #1
On Tue, Sep 17, 2024 at 10:53:07AM +0530, Suraj Kandpal wrote:
> Add the reason for having SHPD_FILTER_CNT value for DISPLAY13 and

It's a bit of a nitpick (and also applies to the first patch), but we're
not allowed to use terms like "DisplayXX" or "GraphicsYY" as proper
nouns anymore.  It's okay to either use the version as an informal
description like "display version XX" or use the official IP name (e.g.,
"Xe_D," "Xe_LPD," etc.).

Also, it's worth noting that the MTP PCH is only ever used on MTL
platforms, which all have display version 14 (known as "Xe_LPD+"), so
the DISPLAY13 here wasn't accurate even if it were allowed.

Aside from the IP naming in the title and commit message, the comment
change itself matches what I see in the DP spec and is

        Reviewed-by: Matt Roper <matthew.d.roper@intel.com>


Matt

> above as 250us instead of 500us.
> 
> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_hotplug_irq.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_hotplug_irq.c b/drivers/gpu/drm/i915/display/intel_hotplug_irq.c
> index 05a9e82cac75..5429d93f67fc 100644
> --- a/drivers/gpu/drm/i915/display/intel_hotplug_irq.c
> +++ b/drivers/gpu/drm/i915/display/intel_hotplug_irq.c
> @@ -1065,6 +1065,10 @@ static void mtp_hpd_irq_setup(struct drm_i915_private *i915)
>  	enabled_irqs = intel_hpd_enabled_irqs(i915, i915->display.hotplug.pch_hpd);
>  	hotplug_irqs = intel_hpd_hotplug_irqs(i915, i915->display.hotplug.pch_hpd);
>  
> +	/*
> +	 * Use 250us here to align with the DP1.4a(Table 3-4) spec as to what the
> +	 * SHPD_FILTER_CNT value should be.
> +	 */
>  	intel_de_write(i915, SHPD_FILTER_CNT, SHPD_FILTER_CNT_250);
>  
>  	mtp_hpd_invert(i915);
> -- 
> 2.43.2
>
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/display/intel_hotplug_irq.c b/drivers/gpu/drm/i915/display/intel_hotplug_irq.c
index 05a9e82cac75..5429d93f67fc 100644
--- a/drivers/gpu/drm/i915/display/intel_hotplug_irq.c
+++ b/drivers/gpu/drm/i915/display/intel_hotplug_irq.c
@@ -1065,6 +1065,10 @@  static void mtp_hpd_irq_setup(struct drm_i915_private *i915)
 	enabled_irqs = intel_hpd_enabled_irqs(i915, i915->display.hotplug.pch_hpd);
 	hotplug_irqs = intel_hpd_hotplug_irqs(i915, i915->display.hotplug.pch_hpd);
 
+	/*
+	 * Use 250us here to align with the DP1.4a(Table 3-4) spec as to what the
+	 * SHPD_FILTER_CNT value should be.
+	 */
 	intel_de_write(i915, SHPD_FILTER_CNT, SHPD_FILTER_CNT_250);
 
 	mtp_hpd_invert(i915);