diff --git a/drivers/gpu/drm/apple/afk.c b/drivers/gpu/drm/apple/afk.c
index a5c271254437..4ea4e00f0a45 100644
--- a/drivers/gpu/drm/apple/afk.c
+++ b/drivers/gpu/drm/apple/afk.c
@@ -1561,11 +1561,16 @@ static void afk_recv_handle_init(struct apple_dcp_afkep *ep, u32 channel,
 					      (ep->dcp->fw_compat == DCP_FIRMWARE_H17P || ep->dcp->fw_compat == DCP_FIRMWARE_V_27_0),
 					      ep->dcp->fw_compat == DCP_FIRMWARE_V_27_0);
 		if (ret == -ENOENT &&
-		    ep->dcp->hw.iomfb_method_profile == DCP_IOMFB_METHODS_H17G) {
+		    (ep->dcp->hw.iomfb_method_profile == DCP_IOMFB_METHODS_H17G ||
+		     (ep->dcp->fw_compat == DCP_FIRMWARE_V_27_0 &&
+		      ep->dcp->hw.firmware_compat == DCP_FIRMWARE_H17P))) {
 			/*
 			 * M5 (H17G) announces powerlog-service with only
-			 * ep-has-desc-mgr and interface-id; match it by the
-			 * announced name, as for props-less announces.
+			 * ep-has-desc-mgr and interface-id, on 26.x and on
+			 * firmware 27 alike (the T8142, an H17P-generation
+			 * processor, is the one that runs firmware 27); match
+			 * it by the announced name, as for props-less
+			 * announces.
 			 */
 			epic_name = NULL;
 			epic_class = NULL;
diff --git a/drivers/gpu/drm/apple/dcp_backlight.c b/drivers/gpu/drm/apple/dcp_backlight.c
index 00f29157241f..c029cca6d300 100644
--- a/drivers/gpu/drm/apple/dcp_backlight.c
+++ b/drivers/gpu/drm/apple/dcp_backlight.c
@@ -429,9 +429,16 @@ int dcp_backlight_prepare(struct apple_dcp *dcp, bool have_surface,
 
 	spin_lock_irqsave(&dcp->backlight.lock, flags);
 	ret = dcp_bl_prepare(&dcp->backlight.state, have_surface, present);
-	/* No reservation: carry the last completed level on an ordinary present. */
-	if (ret == -EALREADY)
+	/*
+	 * No reservation: carry the last completed level on an ordinary
+	 * present, and on one without a surface, which cannot apply a new
+	 * level. A pending level waits for the next present with a surface.
+	 */
+	if (ret == -EALREADY ||
+	    (ret == -ENODATA && !have_surface && dcp->backlight.state.ready)) {
 		present->nits = dcp->backlight.state.actual;
+		ret = -EALREADY;
+	}
 	spin_unlock_irqrestore(&dcp->backlight.lock, flags);
 	return ret;
 }
diff --git a/drivers/gpu/drm/apple/iomfb_v14_7_backlight_test.c b/drivers/gpu/drm/apple/iomfb_v14_7_backlight_test.c
index 3c1fc2f45d53..a84e45338793 100644
--- a/drivers/gpu/drm/apple/iomfb_v14_7_backlight_test.c
+++ b/drivers/gpu/drm/apple/iomfb_v14_7_backlight_test.c
@@ -554,6 +554,25 @@ static void v14_bl_t6030_work(struct kunit *test)
 	KUNIT_EXPECT_TRUE(test, dcp_backlight_pending(f.dcp));
 }
 
+/*
+ * A present without a surface cannot apply a new level: it carries the last
+ * completed one and reserves nothing, so it is still sent, and the request
+ * waits for the next present with a surface.
+ */
+static void v14_bl_surfaceless_present(struct kunit *test)
+{
+	struct v14_bl_fixture f = v14_bl_fixture(test, &dcp_v14_board_t6030, true);
+	struct dcp_backlight_present p = { .nits = U32_MAX };
+
+	v14_bl_request(test, f.dcp, 250);
+	KUNIT_EXPECT_EQ(test, dcp_backlight_prepare(f.dcp, false, &p), -EALREADY);
+	KUNIT_EXPECT_EQ(test, p.nits, DCP_V14_NITS_DEFAULT);
+	KUNIT_EXPECT_TRUE(test, f.dcp->backlight.state.dirty);
+	KUNIT_EXPECT_FALSE(test, f.dcp->backlight.state.in_flight);
+	KUNIT_ASSERT_EQ(test, dcp_backlight_prepare(f.dcp, true, &p), 0);
+	KUNIT_EXPECT_EQ(test, p.nits, 250U);
+}
+
 static struct kunit_case v14_backlight_cases[] = {
 	KUNIT_CASE(v14_bl_binary64),
 	KUNIT_CASE(v14_bl_level_block),
@@ -562,6 +581,7 @@ static struct kunit_case v14_backlight_cases[] = {
 	KUNIT_CASE(v14_bl_gate_transitions),
 	KUNIT_CASE(v14_bl_plan),
 	KUNIT_CASE(v14_bl_policy),
+	KUNIT_CASE(v14_bl_surfaceless_present),
 	KUNIT_CASE(v14_bl_other_boards_untouched),
 	KUNIT_CASE(v14_bl_external_untouched),
 	KUNIT_CASE(v14_bl_t6030_swap_levels),
diff --git a/tools/testing/selftests/drivers/gpu/apple-dcp/edid.py b/tools/testing/selftests/drivers/gpu/apple-dcp/edid.py
index 522740ab2bd3..602cf729aea4 100644
--- a/tools/testing/selftests/drivers/gpu/apple-dcp/edid.py
+++ b/tools/testing/selftests/drivers/gpu/apple-dcp/edid.py
@@ -98,7 +98,7 @@ def function(file,signature):
 struct apple_dcp {
     void *dev;int fw_compat;struct apple_dcp_afkep *dcpavservep;struct apple_connector *connector;
     bool external_physically_absent,hpd_mutex,quiescing,typec_cable_connected;u64 typec_generation;unsigned int nr_modes;
-    struct { int iomfb_method_profile; bool fw_14_7_endpoints; unsigned int num_dptx_ports; } hw; bool ext_dead,external_native;
+    struct { int iomfb_method_profile,firmware_compat; bool fw_14_7_endpoints; unsigned int num_dptx_ports; } hw; bool ext_dead,external_native;
     struct { bool lock,enabled;u64 epoch;int enable_completion;struct apple_epic_service *service,*opened;
              u64 opened_epoch,close_gen,terminated_epoch,close_epoch;bool opening;struct work_struct close_wq; } dcpavserv;
 };