[PATCH RESEND] drm/i915/psr: enable PSR on Apple T2 eDP panels

[PATCH RESEND] drm/i915/psr: enable PSR on Apple T2 eDP panels

[Aditya Garg]

From: Alexander Fischer <alexander.fischer@kait2en.org>

Commit 1035f4a65f58 ("drm/i915: Disable PSR in Apple panels")
disabled PSR on all Apple sinks until i915 gained the required panel
handling.

An AUX trace on a MacBookPro16,2 running macOS 15.7.7 shows the
following writes when the panel is powered on:

  DPCD 0x321 = 0x3c
  DPCD 0x4d2 = 0x01
  DPCD 0x4d1 = 0x03
  DPCD 0x170 = 0x01 (DP_PSR_ENABLE without CRC verification)

Five seconds later, a write of 0x01 to DPCD 0x4d4 occurs between the
BanksiaTcon FIFOEnter() and SRDEnter() events. This register is the
vendor trigger for entering self refresh.

With the three setup writes, CRC verification disabled, and the 0x4d4
trigger added to i915's existing PSR enable sequence, the tested panels
enter PSR1.

Implement this handling as an i915 DPCD quirk. Match the Apple PCI
subsystem vendor in the quirk table, and limit the quirk to Apple-OUI
eDP sinks on systems containing an Apple T2. All other Apple sinks
retain the existing NO_PSR quirk. Override the VBT PSR flag for
matching panels because Apple leaves it clear.

The same sink-side protocol may also be present on T1 and Apple silicon
systems, but leave those systems unchanged until it has been tested
with their display drivers.

Tested on MacBookPro15,1, MacBookPro15,2, MacBookPro16,1,
MacBookPro16,2 and MacBookAir9,1, covering four panel device IDs. All
five enter PSR1 after boot and across suspend/resume, report
DP_PSR_SINK_ACTIVE_SINK_SYNCED, and show no sink errors.

Tested-by: Andre Eikmeyer <dev@deq.rocks>
Tested-by: Yossef Osman <yossef.osman@proton.me>
Signed-off-by: Alexander Fischer <alexander.fischer@kait2en.org>
Signed-off-by: Aditya Garg <aditya.garg@linux.dev>
---
Changes in v4:
- Rebase onto drm-tip; use drm_dp_dpcd_write_byte() for the new
  writes to match the conversion of intel_psr.c

Changes in v3:
- Match the Apple PCI subsystem vendor in the DPCD quirk table
  (Lukas Wunner)

Changes in v2:
- Use pci_dev_present() instead of pci_get_device()/pci_dev_put(),
  which also drops the local PCI_DEVICE_ID define (Lukas Wunner)
---
 drivers/gpu/drm/i915/display/intel_psr.c    | 28 +++++++++++++++++++--
 drivers/gpu/drm/i915/display/intel_quirks.c | 28 +++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_quirks.h |  1 +
 3 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
index 00d0146b2..c3bde5b64 100644
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -228,6 +228,9 @@ static bool psr_global_enabled(struct intel_dp *intel_dp)
 
 	switch (intel_dp->psr.debug & I915_PSR_DEBUG_MODE_MASK) {
 	case I915_PSR_DEBUG_DEFAULT:
+		if (intel_has_dpcd_quirk(intel_dp, QUIRK_APPLE_PSR_HANDSHAKE))
+			return true;
+
 		return intel_dp_is_edp(intel_dp) ?
 			connector->panel.vbt.psr.enable : true;
 	case I915_PSR_DEBUG_DISABLE:
@@ -667,7 +670,8 @@ static void _psr_init_dpcd(struct intel_dp *intel_dp, struct intel_connector *co
 	drm_dbg_kms(display->drm, "eDP panel supports PSR version %x\n",
 		    connector->dp.psr_caps.dpcd[0]);
 
-	if (drm_dp_has_quirk(&intel_dp->desc, DP_DPCD_QUIRK_NO_PSR)) {
+	if (drm_dp_has_quirk(&intel_dp->desc, DP_DPCD_QUIRK_NO_PSR) &&
+	    !intel_has_dpcd_quirk(intel_dp, QUIRK_APPLE_PSR_HANDSHAKE)) {
 		drm_dbg_kms(display->drm,
 			    "PSR support not currently available for this panel\n");
 		return;
@@ -807,19 +811,36 @@ static void _panel_replay_enable_sink(struct intel_dp *intel_dp,
 	drm_dp_dpcd_write_byte(&intel_dp->aux, PANEL_REPLAY_CONFIG3, panel_replay_config_3);
 }
 
+/* Undocumented Apple eDP sink registers */
+#define APPLE_PSR_SETUP_1	0x321
+#define APPLE_PSR_SETUP_2	0x4d2
+#define APPLE_PSR_SETUP_3	0x4d1
+#define APPLE_PSR_TRIGGER	0x4d4
+
+static void psr_apple_prepare_sink(struct intel_dp *intel_dp)
+{
+	drm_dp_dpcd_write_byte(&intel_dp->aux, APPLE_PSR_SETUP_1, 0x3c);
+	drm_dp_dpcd_write_byte(&intel_dp->aux, APPLE_PSR_SETUP_2, 0x01);
+	drm_dp_dpcd_write_byte(&intel_dp->aux, APPLE_PSR_SETUP_3, 0x03);
+}
+
 static void _psr_enable_sink(struct intel_dp *intel_dp,
 			     const struct intel_crtc_state *crtc_state)
 {
 	struct intel_display *display = to_intel_display(intel_dp);
+	bool apple_psr = intel_has_dpcd_quirk(intel_dp, QUIRK_APPLE_PSR_HANDSHAKE);
 	u8 val = 0;
 
+	if (apple_psr)
+		psr_apple_prepare_sink(intel_dp);
+
 	if (crtc_state->has_sel_update) {
 		val |= DP_PSR_ENABLE_PSR2 | DP_PSR_IRQ_HPD_WITH_CRC_ERRORS;
 	} else {
 		if (intel_dp->psr.link_standby)
 			val |= DP_PSR_MAIN_LINK_ACTIVE;
 
-		if (DISPLAY_VER(display) >= 8)
+		if (DISPLAY_VER(display) >= 8 && !apple_psr)
 			val |= DP_PSR_CRC_VERIFICATION;
 	}
 
@@ -835,6 +856,9 @@ static void _psr_enable_sink(struct intel_dp *intel_dp,
 
 	val |= DP_PSR_ENABLE;
 	drm_dp_dpcd_write_byte(&intel_dp->aux, DP_PSR_EN_CFG, val);
+
+	if (apple_psr)
+		drm_dp_dpcd_write_byte(&intel_dp->aux, APPLE_PSR_TRIGGER, 0x01);
 }
 
 static void intel_psr_enable_sink(struct intel_dp *intel_dp,
diff --git a/drivers/gpu/drm/i915/display/intel_quirks.c b/drivers/gpu/drm/i915/display/intel_quirks.c
index 7d7db774d..8e9c851c2 100644
--- a/drivers/gpu/drm/i915/display/intel_quirks.c
+++ b/drivers/gpu/drm/i915/display/intel_quirks.c
@@ -9,6 +9,7 @@
 
 #include "intel_display_core.h"
 #include "intel_display_types.h"
+#include "intel_dp.h"
 #include "intel_quirks.h"
 
 static void intel_set_quirk(struct intel_display *display, enum intel_quirk_id quirk)
@@ -100,6 +101,25 @@ static void quirk_disable_psr2(struct intel_display *display)
 	drm_info(display->drm, "PSR2 support not currently available for this setup, applying disable PSR2 quirk\n");
 }
 
+static void quirk_apple_psr_handshake(struct intel_dp *intel_dp)
+{
+	static const struct pci_device_id t2_ids[] = {
+		/* Apple T2 */
+		{PCI_DEVICE(PCI_VENDOR_ID_APPLE, 0x1801)},
+		{}
+	};
+	struct intel_display *display = to_intel_display(intel_dp);
+
+	if (!intel_dp_is_edp(intel_dp))
+		return;
+
+	if (!pci_dev_present(t2_ids))
+		return;
+
+	intel_set_dpcd_quirk(intel_dp, QUIRK_APPLE_PSR_HANDSHAKE);
+	drm_info(display->drm, "Applying Apple PSR handshake quirk\n");
+}
+
 struct intel_quirk {
 	int device;
 	int subsystem_vendor;
@@ -289,6 +309,14 @@ static const struct intel_dpcd_quirk intel_dpcd_quirks[] = {
 		.sink_oui = SINK_OUI(0x00, 0x22, 0xb9),
 		.hook = quirk_disable_edp_panel_replay,
 	},
+	/* Apple T2 eDP panels */
+	{
+		.device = DEVICE_ID_ANY,
+		.subsystem_vendor = PCI_VENDOR_ID_APPLE,
+		.subsystem_device = PCI_ANY_ID,
+		.sink_oui = SINK_OUI(0x00, 0x10, 0xfa),
+		.hook = quirk_apple_psr_handshake,
+	},
 };
 
 void intel_init_quirks(struct intel_display *display)
diff --git a/drivers/gpu/drm/i915/display/intel_quirks.h b/drivers/gpu/drm/i915/display/intel_quirks.h
index 970a4fe52..7b863d408 100644
--- a/drivers/gpu/drm/i915/display/intel_quirks.h
+++ b/drivers/gpu/drm/i915/display/intel_quirks.h
@@ -23,6 +23,7 @@ enum intel_quirk_id {
 	QUIRK_EDP_LIMIT_RATE_HBR2,
 	QUIRK_DISABLE_EDP_PANEL_REPLAY,
 	QUIRK_DISABLE_PSR2,
+	QUIRK_APPLE_PSR_HANDSHAKE,
 };
 
 void intel_init_quirks(struct intel_display *display);
-- 
2.56.0

Re: [PATCH RESEND] drm/i915/psr: enable PSR on Apple T2 eDP panels

[Ville Syrjälä]

On Thu, Nov 12, 2026 at 10:29:56PM +0530, Aditya Garg wrote:
> From: Alexander Fischer <alexander.fischer@kait2en.org>
> 
> Commit 1035f4a65f58 ("drm/i915: Disable PSR in Apple panels")
> disabled PSR on all Apple sinks until i915 gained the required panel
> handling.
> 
> An AUX trace on a MacBookPro16,2 running macOS 15.7.7 shows the
> following writes when the panel is powered on:
> 
>   DPCD 0x321 = 0x3c

That's in the source device specific range. I think technically
the registers there can only be considered valid after writing
the appropriate source OUI to 0x300-0x302. Which source OUI
does the Apple driver write there?

>   DPCD 0x4d2 = 0x01
>   DPCD 0x4d1 = 0x03
>   DPCD 0x170 = 0x01 (DP_PSR_ENABLE without CRC verification)
> 
> Five seconds later, a write of 0x01 to DPCD 0x4d4 occurs between the
> BanksiaTcon FIFOEnter() and SRDEnter() events. This register is the
> vendor trigger for entering self refresh.
> 
> With the three setup writes, CRC verification disabled, and the 0x4d4
> trigger added to i915's existing PSR enable sequence, the tested panels
> enter PSR1.
> 
> Implement this handling as an i915 DPCD quirk. Match the Apple PCI
> subsystem vendor in the quirk table, and limit the quirk to Apple-OUI
> eDP sinks on systems containing an Apple T2. All other Apple sinks
> retain the existing NO_PSR quirk. Override the VBT PSR flag for
> matching panels because Apple leaves it clear.
> 
> The same sink-side protocol may also be present on T1 and Apple silicon
> systems, but leave those systems unchanged until it has been tested
> with their display drivers.
> 
> Tested on MacBookPro15,1, MacBookPro15,2, MacBookPro16,1,
> MacBookPro16,2 and MacBookAir9,1, covering four panel device IDs. All
> five enter PSR1 after boot and across suspend/resume, report
> DP_PSR_SINK_ACTIVE_SINK_SYNCED, and show no sink errors.
> 
> Tested-by: Andre Eikmeyer <dev@deq.rocks>
> Tested-by: Yossef Osman <yossef.osman@proton.me>
> Signed-off-by: Alexander Fischer <alexander.fischer@kait2en.org>
> Signed-off-by: Aditya Garg <aditya.garg@linux.dev>
> ---
> Changes in v4:
> - Rebase onto drm-tip; use drm_dp_dpcd_write_byte() for the new
>   writes to match the conversion of intel_psr.c
> 
> Changes in v3:
> - Match the Apple PCI subsystem vendor in the DPCD quirk table
>   (Lukas Wunner)
> 
> Changes in v2:
> - Use pci_dev_present() instead of pci_get_device()/pci_dev_put(),
>   which also drops the local PCI_DEVICE_ID define (Lukas Wunner)
> ---
>  drivers/gpu/drm/i915/display/intel_psr.c    | 28 +++++++++++++++++++--
>  drivers/gpu/drm/i915/display/intel_quirks.c | 28 +++++++++++++++++++++
>  drivers/gpu/drm/i915/display/intel_quirks.h |  1 +
>  3 files changed, 55 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
> index 00d0146b2..c3bde5b64 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -228,6 +228,9 @@ static bool psr_global_enabled(struct intel_dp *intel_dp)
>  
>  	switch (intel_dp->psr.debug & I915_PSR_DEBUG_MODE_MASK) {
>  	case I915_PSR_DEBUG_DEFAULT:
> +		if (intel_has_dpcd_quirk(intel_dp, QUIRK_APPLE_PSR_HANDSHAKE))
> +			return true;
> +
>  		return intel_dp_is_edp(intel_dp) ?
>  			connector->panel.vbt.psr.enable : true;
>  	case I915_PSR_DEBUG_DISABLE:
> @@ -667,7 +670,8 @@ static void _psr_init_dpcd(struct intel_dp *intel_dp, struct intel_connector *co
>  	drm_dbg_kms(display->drm, "eDP panel supports PSR version %x\n",
>  		    connector->dp.psr_caps.dpcd[0]);
>  
> -	if (drm_dp_has_quirk(&intel_dp->desc, DP_DPCD_QUIRK_NO_PSR)) {
> +	if (drm_dp_has_quirk(&intel_dp->desc, DP_DPCD_QUIRK_NO_PSR) &&
> +	    !intel_has_dpcd_quirk(intel_dp, QUIRK_APPLE_PSR_HANDSHAKE)) {
>  		drm_dbg_kms(display->drm,
>  			    "PSR support not currently available for this panel\n");
>  		return;
> @@ -807,19 +811,36 @@ static void _panel_replay_enable_sink(struct intel_dp *intel_dp,
>  	drm_dp_dpcd_write_byte(&intel_dp->aux, PANEL_REPLAY_CONFIG3, panel_replay_config_3);
>  }
>  
> +/* Undocumented Apple eDP sink registers */
> +#define APPLE_PSR_SETUP_1	0x321
> +#define APPLE_PSR_SETUP_2	0x4d2
> +#define APPLE_PSR_SETUP_3	0x4d1
> +#define APPLE_PSR_TRIGGER	0x4d4

Maybe these should include "SOURCE" vs. "SINK" in the
name as well.

> +
> +static void psr_apple_prepare_sink(struct intel_dp *intel_dp)
> +{
> +	drm_dp_dpcd_write_byte(&intel_dp->aux, APPLE_PSR_SETUP_1, 0x3c);
> +	drm_dp_dpcd_write_byte(&intel_dp->aux, APPLE_PSR_SETUP_2, 0x01);
> +	drm_dp_dpcd_write_byte(&intel_dp->aux, APPLE_PSR_SETUP_3, 0x03);
> +}
> +
>  static void _psr_enable_sink(struct intel_dp *intel_dp,
>  			     const struct intel_crtc_state *crtc_state)
>  {
>  	struct intel_display *display = to_intel_display(intel_dp);
> +	bool apple_psr = intel_has_dpcd_quirk(intel_dp, QUIRK_APPLE_PSR_HANDSHAKE);
>  	u8 val = 0;
>  
> +	if (apple_psr)
> +		psr_apple_prepare_sink(intel_dp);
> +
>  	if (crtc_state->has_sel_update) {
>  		val |= DP_PSR_ENABLE_PSR2 | DP_PSR_IRQ_HPD_WITH_CRC_ERRORS;
>  	} else {
>  		if (intel_dp->psr.link_standby)
>  			val |= DP_PSR_MAIN_LINK_ACTIVE;
>  
> -		if (DISPLAY_VER(display) >= 8)
> +		if (DISPLAY_VER(display) >= 8 && !apple_psr)
>  			val |= DP_PSR_CRC_VERIFICATION;
>  	}
>  
> @@ -835,6 +856,9 @@ static void _psr_enable_sink(struct intel_dp *intel_dp,
>  
>  	val |= DP_PSR_ENABLE;
>  	drm_dp_dpcd_write_byte(&intel_dp->aux, DP_PSR_EN_CFG, val);
> +
> +	if (apple_psr)
> +		drm_dp_dpcd_write_byte(&intel_dp->aux, APPLE_PSR_TRIGGER, 0x01);
>  }
>  
>  static void intel_psr_enable_sink(struct intel_dp *intel_dp,
> diff --git a/drivers/gpu/drm/i915/display/intel_quirks.c b/drivers/gpu/drm/i915/display/intel_quirks.c
> index 7d7db774d..8e9c851c2 100644
> --- a/drivers/gpu/drm/i915/display/intel_quirks.c
> +++ b/drivers/gpu/drm/i915/display/intel_quirks.c
> @@ -9,6 +9,7 @@
>  
>  #include "intel_display_core.h"
>  #include "intel_display_types.h"
> +#include "intel_dp.h"
>  #include "intel_quirks.h"
>  
>  static void intel_set_quirk(struct intel_display *display, enum intel_quirk_id quirk)
> @@ -100,6 +101,25 @@ static void quirk_disable_psr2(struct intel_display *display)
>  	drm_info(display->drm, "PSR2 support not currently available for this setup, applying disable PSR2 quirk\n");
>  }
>  
> +static void quirk_apple_psr_handshake(struct intel_dp *intel_dp)
> +{
> +	static const struct pci_device_id t2_ids[] = {
> +		/* Apple T2 */
> +		{PCI_DEVICE(PCI_VENDOR_ID_APPLE, 0x1801)},

This is some other device on these systems? Can't just
match on the GPU subsys vendor/device + sink OUI alone?

> +		{}
> +	};
> +	struct intel_display *display = to_intel_display(intel_dp);
> +
> +	if (!intel_dp_is_edp(intel_dp))
> +		return;
> +
> +	if (!pci_dev_present(t2_ids))
> +		return;
> +
> +	intel_set_dpcd_quirk(intel_dp, QUIRK_APPLE_PSR_HANDSHAKE);
> +	drm_info(display->drm, "Applying Apple PSR handshake quirk\n");
> +}
> +
>  struct intel_quirk {
>  	int device;
>  	int subsystem_vendor;
> @@ -289,6 +309,14 @@ static const struct intel_dpcd_quirk intel_dpcd_quirks[] = {
>  		.sink_oui = SINK_OUI(0x00, 0x22, 0xb9),
>  		.hook = quirk_disable_edp_panel_replay,
>  	},
> +	/* Apple T2 eDP panels */
> +	{
> +		.device = DEVICE_ID_ANY,
> +		.subsystem_vendor = PCI_VENDOR_ID_APPLE,
> +		.subsystem_device = PCI_ANY_ID,
> +		.sink_oui = SINK_OUI(0x00, 0x10, 0xfa),
> +		.hook = quirk_apple_psr_handshake,
> +	},
>  };
>  
>  void intel_init_quirks(struct intel_display *display)
> diff --git a/drivers/gpu/drm/i915/display/intel_quirks.h b/drivers/gpu/drm/i915/display/intel_quirks.h
> index 970a4fe52..7b863d408 100644
> --- a/drivers/gpu/drm/i915/display/intel_quirks.h
> +++ b/drivers/gpu/drm/i915/display/intel_quirks.h
> @@ -23,6 +23,7 @@ enum intel_quirk_id {
>  	QUIRK_EDP_LIMIT_RATE_HBR2,
>  	QUIRK_DISABLE_EDP_PANEL_REPLAY,
>  	QUIRK_DISABLE_PSR2,
> +	QUIRK_APPLE_PSR_HANDSHAKE,
>  };
>  
>  void intel_init_quirks(struct intel_display *display);
> -- 
> 2.56.0

-- 
Ville Syrjälä
Intel

Re: [PATCH RESEND] drm/i915/psr: enable PSR on Apple T2 eDP panels

[Alexander Fischer]

Hi Ville,

Thanks for reviewing this.

> Which source OUI does the Apple driver write there?

When I first tried to get PSR working, I also tried writing Apple's
00:10:fa from i915 before link training. It made no difference. I then
traced macOS and found the extra writes in this patch. With those
added, PSR worked, leaving i915's Intel source OUI unchanged.

After your question, I read back 0x300-0x302 on the MacBookPro16,2
under macOS 26.6.1 and got 00 00 00 twice. The same read method
returned the expected sink identity at 0x400. I haven't captured boot,
so I can't say whether a different source OUI was set earlier.

> Maybe these should include "SOURCE" vs. "SINK" in the name as well.

Agreed. I'll use APPLE_SOURCE_PSR_SETUP for 0x321 and APPLE_SINK_PSR_*
for the other registers, and update the comment.

> This is some other device on these systems? Can't just match on the
GPU subsys vendor/device + sink OUI alone?

Yes, 106b:1801 is the separate T2 Bridge Controller. We only check its
presence to restrict the quirk to T2 systems and retain NO_PSR on older
untested Macs. The current subsystem device ID is a wildcard.

Specific GPU subsystem vendor/device pairs plus the sink OUI could
replace this. I chose T2 detection to avoid a per-model list; the five
tested models are only a subset of what matches. If you prefer explicit
subsystem IDs, I can collect and verify those for the tested machines.

Best regards,
Alex