diff mbox series

[v4,04/15] hw/display/apple-gfx: Adds configurable mode list

Message ID 20241024102813.9855-5-phil@philjordan.eu (mailing list archive)
State New
Headers show
Series macOS PV Graphics and new vmapple machine type | expand

Commit Message

Phil Dennis-Jordan Oct. 24, 2024, 10:28 a.m. UTC 
This change adds a property 'display_modes' on the graphics device
which permits specifying a list of display modes. (screen resolution
and refresh rate)

The property is an array of a custom type to make the syntax slightly
less awkward to use, for example:

-device '{"driver":"apple-gfx-pci", "display-modes":["1920x1080@60", "3840x2160@60"]}'

Signed-off-by: Phil Dennis-Jordan <phil@philjordan.eu>
---

v4:

 * Switched to the native array property type, which recently gained
	 command line support.
 * The property has also been added to the -mmio variant.
 * Tidied up the code a little.

 hw/display/apple-gfx-mmio.m |   8 +++
 hw/display/apple-gfx-pci.m  |   9 ++-
 hw/display/apple-gfx.h      |  12 ++++
 hw/display/apple-gfx.m      | 127 ++++++++++++++++++++++++++++++++----
 hw/display/trace-events     |   2 +
 5 files changed, 145 insertions(+), 13 deletions(-)

Comments

Akihiko Odaki Oct. 26, 2024, 5:15 a.m. UTC | #1 
On 2024/10/24 19:28, Phil Dennis-Jordan wrote:
> This change adds a property 'display_modes' on the graphics device
> which permits specifying a list of display modes. (screen resolution
> and refresh rate)
> 
> The property is an array of a custom type to make the syntax slightly
> less awkward to use, for example:
> 
> -device '{"driver":"apple-gfx-pci", "display-modes":["1920x1080@60", "3840x2160@60"]}'
> 
> Signed-off-by: Phil Dennis-Jordan <phil@philjordan.eu>
> ---
> 
> v4:
> 
>   * Switched to the native array property type, which recently gained
> 	 command line support.
>   * The property has also been added to the -mmio variant.
>   * Tidied up the code a little.
> 
>   hw/display/apple-gfx-mmio.m |   8 +++
>   hw/display/apple-gfx-pci.m  |   9 ++-
>   hw/display/apple-gfx.h      |  12 ++++
>   hw/display/apple-gfx.m      | 127 ++++++++++++++++++++++++++++++++----
>   hw/display/trace-events     |   2 +
>   5 files changed, 145 insertions(+), 13 deletions(-)
> 
> diff --git a/hw/display/apple-gfx-mmio.m b/hw/display/apple-gfx-mmio.m
> index 06131bc23f1..5d427c7005e 100644
> --- a/hw/display/apple-gfx-mmio.m
> +++ b/hw/display/apple-gfx-mmio.m
> @@ -261,6 +261,12 @@ static void apple_gfx_mmio_reset(Object *obj, ResetType type)
>       [s->common.pgdev reset];
>   }
>   
> +static Property apple_gfx_mmio_properties[] = {
> +    DEFINE_PROP_ARRAY("display-modes", AppleGFXMMIOState,
> +                      common.num_display_modes, common.display_modes,
> +                      qdev_prop_display_mode, AppleGFXDisplayMode),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
>   
>   static void apple_gfx_mmio_class_init(ObjectClass *klass, void *data)
>   {
> @@ -270,6 +276,8 @@ static void apple_gfx_mmio_class_init(ObjectClass *klass, void *data)
>       rc->phases.hold = apple_gfx_mmio_reset;
>       dc->hotpluggable = false;
>       dc->realize = apple_gfx_mmio_realize;
> +
> +    device_class_set_props(dc, apple_gfx_mmio_properties);
>   }
>   
>   static TypeInfo apple_gfx_mmio_types[] = {
> diff --git a/hw/display/apple-gfx-pci.m b/hw/display/apple-gfx-pci.m
> index 4ee26dde422..32e81bbef8b 100644
> --- a/hw/display/apple-gfx-pci.m
> +++ b/hw/display/apple-gfx-pci.m
> @@ -115,6 +115,13 @@ static void apple_gfx_pci_reset(Object *obj, ResetType type)
>       [s->common.pgdev reset];
>   }
>   
> +static Property apple_gfx_pci_properties[] = {
> +    DEFINE_PROP_ARRAY("display-modes", AppleGFXPCIState,
> +                      common.num_display_modes, common.display_modes,
> +                      qdev_prop_display_mode, AppleGFXDisplayMode),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
>   static void apple_gfx_pci_class_init(ObjectClass *klass, void *data)
>   {
>       DeviceClass *dc = DEVICE_CLASS(klass);
> @@ -132,7 +139,7 @@ static void apple_gfx_pci_class_init(ObjectClass *klass, void *data)
>       pci->class_id = PCI_CLASS_DISPLAY_OTHER;
>       pci->realize = apple_gfx_pci_realize;
>   
> -    // TODO: Property for setting mode list
> +    device_class_set_props(dc, apple_gfx_pci_properties);
>   }
>   
>   static TypeInfo apple_gfx_pci_types[] = {
> diff --git a/hw/display/apple-gfx.h b/hw/display/apple-gfx.h
> index 39931fba65a..d2c6a14229a 100644
> --- a/hw/display/apple-gfx.h
> +++ b/hw/display/apple-gfx.h
> @@ -9,6 +9,7 @@
>   #import <ParavirtualizedGraphics/ParavirtualizedGraphics.h>
>   #include "qemu/typedefs.h"
>   #include "exec/memory.h"
> +#include "hw/qdev-properties.h"
>   #include "ui/surface.h"
>   
>   @class PGDeviceDescriptor;
> @@ -20,6 +21,7 @@
>   
>   typedef QTAILQ_HEAD(, PGTask_s) PGTaskList;
>   
> +struct AppleGFXDisplayMode;
>   struct AppleGFXMapMemoryJob;
>   typedef struct AppleGFXState {
>       MemoryRegion iomem_gfx;
> @@ -31,6 +33,8 @@ typedef struct AppleGFXState {
>       id<MTLCommandQueue> mtl_queue;
>       bool cursor_show;
>       QEMUCursor *cursor;
> +    struct AppleGFXDisplayMode *display_modes;
> +    uint32_t num_display_modes;
>   
>       /* For running PVG memory-mapping requests in the AIO context */
>       QemuCond job_cond;
> @@ -47,6 +51,12 @@ typedef struct AppleGFXState {
>       id<MTLTexture> texture;
>   } AppleGFXState;
>   
> +typedef struct AppleGFXDisplayMode {
> +    uint16_t width_px;
> +    uint16_t height_px;
> +    uint16_t refresh_rate_hz;
> +} AppleGFXDisplayMode;
> +
>   void apple_gfx_common_init(Object *obj, AppleGFXState *s, const char* obj_name);
>   void apple_gfx_common_realize(AppleGFXState *s, PGDeviceDescriptor *desc,
>                                 Error **errp);
> @@ -54,5 +64,7 @@ uintptr_t apple_gfx_host_address_for_gpa_range(uint64_t guest_physical,
>                                                  uint64_t length, bool read_only);
>   void apple_gfx_await_bh_job(AppleGFXState *s, bool *job_done_flag);
>   
> +extern const PropertyInfo qdev_prop_display_mode;
> +
>   #endif
>   
> diff --git a/hw/display/apple-gfx.m b/hw/display/apple-gfx.m
> index 46be9957f69..42b601329fb 100644
> --- a/hw/display/apple-gfx.m
> +++ b/hw/display/apple-gfx.m
> @@ -28,9 +28,10 @@
>   #include "qapi/error.h"
>   #include "ui/console.h"
>   
> -static const PGDisplayCoord_t apple_gfx_modes[] = {
> -    { .x = 1440, .y = 1080 },
> -    { .x = 1280, .y = 1024 },
> +static const AppleGFXDisplayMode apple_gfx_default_modes[] = {
> +    { 1920, 1080, 60 },
> +    { 1440, 1080, 60 },
> +    { 1280, 1024, 60 },
>   };
>   
>   /* This implements a type defined in <ParavirtualizedGraphics/PGDevice.h>
> @@ -303,7 +304,6 @@ static void set_mode(AppleGFXState *s, uint32_t width, uint32_t height)
>   static void create_fb(AppleGFXState *s)
>   {
>       s->con = graphic_console_init(NULL, 0, &apple_gfx_fb_ops, s);
> -    set_mode(s, 1440, 1080);
>   
>       s->cursor_show = true;
>   }
> @@ -628,20 +628,25 @@ static void apple_gfx_register_task_mapping_handlers(AppleGFXState *s,
>       return disp_desc;
>   }
>   
> -static NSArray<PGDisplayMode*>* apple_gfx_prepare_display_mode_array(void)
> +static NSArray<PGDisplayMode*>* apple_gfx_create_display_mode_array(
> +    const AppleGFXDisplayMode display_modes[], uint32_t display_mode_count)
>   {
> -    PGDisplayMode *modes[ARRAY_SIZE(apple_gfx_modes)];
> +    PGDisplayMode **modes = alloca(sizeof(modes[0]) * display_mode_count);

Avoid alloca().

>       NSArray<PGDisplayMode*>* mode_array = nil;
> -    int i;
> +    uint32_t i;
>   
> -    for (i = 0; i < ARRAY_SIZE(apple_gfx_modes); i++) {
> +    for (i = 0; i < display_mode_count; i++) {
> +        const AppleGFXDisplayMode *mode = &display_modes[i];
> +        trace_apple_gfx_display_mode(i, mode->width_px, mode->height_px);
> +        PGDisplayCoord_t mode_size = { mode->width_px, mode->height_px };
>           modes[i] =
> -            [[PGDisplayMode alloc] initWithSizeInPixels:apple_gfx_modes[i] refreshRateInHz:60.];
> +            [[PGDisplayMode alloc] initWithSizeInPixels:mode_size
> +                                        refreshRateInHz:mode->refresh_rate_hz];
>       }
>   
> -    mode_array = [NSArray arrayWithObjects:modes count:ARRAY_SIZE(apple_gfx_modes)];
> +    mode_array = [NSArray arrayWithObjects:modes count:display_mode_count];
>   
> -    for (i = 0; i < ARRAY_SIZE(apple_gfx_modes); i++) {
> +    for (i = 0; i < display_mode_count; i++) {
>           [modes[i] release];
>           modes[i] = nil;
>       }
> @@ -679,6 +684,8 @@ void apple_gfx_common_realize(AppleGFXState *s, PGDeviceDescriptor *desc,
>                                 Error **errp)
>   {
>       PGDisplayDescriptor *disp_desc = nil;
> +    const AppleGFXDisplayMode *display_modes = apple_gfx_default_modes;
> +    int num_display_modes = ARRAY_SIZE(apple_gfx_default_modes);
>   
>       if (apple_gfx_mig_blocker == NULL) {
>           error_setg(&apple_gfx_mig_blocker,
> @@ -704,10 +711,106 @@ void apple_gfx_common_realize(AppleGFXState *s, PGDeviceDescriptor *desc,
>       s->pgdisp = [s->pgdev newDisplayWithDescriptor:disp_desc
>                                                 port:0 serialNum:1234];
>       [disp_desc release];
> -    s->pgdisp.modeList = apple_gfx_prepare_display_mode_array();
> +
> +    if (s->display_modes != NULL && s->num_display_modes > 0) {
> +        trace_apple_gfx_common_realize_modes_property(s->num_display_modes);
> +        display_modes = s->display_modes;
> +        num_display_modes = s->num_display_modes;
> +    }
> +    s->pgdisp.modeList =
> +        apple_gfx_create_display_mode_array(display_modes, num_display_modes);
>   
>       create_fb(s);
>   
>       qemu_mutex_init(&s->job_mutex);
>       qemu_cond_init(&s->job_cond);
>   }
> +
> +static void apple_gfx_get_display_mode(Object *obj, Visitor *v,
> +                                       const char *name, void *opaque,
> +                                       Error **errp)
> +{
> +    Property *prop = opaque;
> +    AppleGFXDisplayMode *mode = object_field_prop_ptr(obj, prop);
> +    /* 3 uint16s (max 5 digits) and 2 separator characters + nul. */
> +    static const size_t buffer_size = 5 * 3 + 2 + 1;
> +
> +    char buffer[buffer_size];

I prefer it to be written as: char buffer[5 * 3 + 2 + 1];
to avoid the indirection by having another variable.

 > +    char *pos = buffer;> +
> +    int rc = snprintf(buffer, buffer_size,
> +                      "%"PRIu16"x%"PRIu16"@%"PRIu16,
> +                      mode->width_px, mode->height_px,
> +                      mode->refresh_rate_hz);
> +    assert(rc < buffer_size);
> +
> +    visit_type_str(v, name, &pos, errp);
> +}
> +
> +static void apple_gfx_set_display_mode(Object *obj, Visitor *v,
> +                                       const char *name, void *opaque,
> +                                       Error **errp)
> +{
> +    Property *prop = opaque;
> +    AppleGFXDisplayMode *mode = object_field_prop_ptr(obj, prop);
> +    Error *local_err = NULL;
> +    const char *endptr;
> +    char *str;
> +    int ret;
> +    unsigned int val;
> +
> +    visit_type_str(v, name, &str, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        return;
> +    }
> +
> +    endptr = str;
> +
> +    ret = qemu_strtoui(endptr, &endptr, 10, &val);
> +    if (ret || val > UINT16_MAX || val == 0) {
> +        error_setg(errp, "width in '%s' must be a decimal integer number "
> +                   "of pixels in the range 1..65535", name);
> +        goto out;
> +    }
> +    mode->width_px = val;
> +    if (*endptr != 'x') {
> +        goto separator_error;
> +    }
> +
> +    ret = qemu_strtoui(endptr + 1, &endptr, 10, &val);
> +    if (ret || val > UINT16_MAX || val == 0) {
> +        error_setg(errp, "height in '%s' must be a decimal integer number "
> +                   "of pixels in the range 1..65535", name);
> +        goto out;
> +    }
> +    mode->height_px = val;
> +    if (*endptr != '@') {
> +        goto separator_error;
> +    }
> +
> +    ret = qemu_strtoui(endptr + 1, &endptr, 10, &val);

Use qemu_strtoi() or it will have a perculiar behavior with negative 
values; see the comment in util/cutils.c for details.

> +    if (ret) {
> +        error_setg(errp, "refresh rate in '%s'"
> +                   " must be a non-negative decimal integer (Hertz)", name);
> +    }
> +    mode->refresh_rate_hz = val;
> +
> +    goto out;
> +
> +separator_error:
> +    error_setg(errp, "Each display mode takes the format "
> +               "'<width>x<height>@<rate>'");
> +out:
> +    g_free(str);

Use g_autofree. docs/devel/style.rst has some explanation.

> +    return;
> +}
> +
> +const PropertyInfo qdev_prop_display_mode = {
> +    .name  = "display_mode",
> +    .description =
> +        "Display mode in pixels and Hertz, as <width>x<height>@<refresh-rate> "
> +        "Example: 3840x2160@60",
> +    .get   = apple_gfx_get_display_mode,
> +    .set   = apple_gfx_set_display_mode,
> +};
> diff --git a/hw/display/trace-events b/hw/display/trace-events
> index 214998312b9..2780239dbde 100644
> --- a/hw/display/trace-events
> +++ b/hw/display/trace-events
> @@ -209,6 +209,8 @@ apple_gfx_cursor_set(uint32_t bpp, uint64_t width, uint64_t height) "bpp=%d widt
>   apple_gfx_cursor_show(uint32_t show) "show=%d"
>   apple_gfx_cursor_move(void) ""
>   apple_gfx_common_init(const char *device_name, size_t mmio_size) "device: %s; MMIO size: %zu bytes"
> +apple_gfx_common_realize_modes_property(uint32_t num_modes) "using %u modes supplied by 'display-modes' device property"
> +apple_gfx_display_mode(uint32_t mode_idx, uint16_t width_px, uint16_t height_px) "mode %2"PRIu32": %4"PRIu16"x%4"PRIu16
>   
>   # apple-gfx-mmio.m
>   apple_gfx_mmio_iosfc_read(uint64_t offset, uint64_t res) "offset=0x%"PRIx64" res=0x%"PRIx64
diff mbox series

Patch

diff --git a/hw/display/apple-gfx-mmio.m b/hw/display/apple-gfx-mmio.m
index 06131bc23f1..5d427c7005e 100644
--- a/hw/display/apple-gfx-mmio.m
+++ b/hw/display/apple-gfx-mmio.m
@@ -261,6 +261,12 @@  static void apple_gfx_mmio_reset(Object *obj, ResetType type)
     [s->common.pgdev reset];
 }
 
+static Property apple_gfx_mmio_properties[] = {
+    DEFINE_PROP_ARRAY("display-modes", AppleGFXMMIOState,
+                      common.num_display_modes, common.display_modes,
+                      qdev_prop_display_mode, AppleGFXDisplayMode),
+    DEFINE_PROP_END_OF_LIST(),
+};
 
 static void apple_gfx_mmio_class_init(ObjectClass *klass, void *data)
 {
@@ -270,6 +276,8 @@  static void apple_gfx_mmio_class_init(ObjectClass *klass, void *data)
     rc->phases.hold = apple_gfx_mmio_reset;
     dc->hotpluggable = false;
     dc->realize = apple_gfx_mmio_realize;
+
+    device_class_set_props(dc, apple_gfx_mmio_properties);
 }
 
 static TypeInfo apple_gfx_mmio_types[] = {
diff --git a/hw/display/apple-gfx-pci.m b/hw/display/apple-gfx-pci.m
index 4ee26dde422..32e81bbef8b 100644
--- a/hw/display/apple-gfx-pci.m
+++ b/hw/display/apple-gfx-pci.m
@@ -115,6 +115,13 @@  static void apple_gfx_pci_reset(Object *obj, ResetType type)
     [s->common.pgdev reset];
 }
 
+static Property apple_gfx_pci_properties[] = {
+    DEFINE_PROP_ARRAY("display-modes", AppleGFXPCIState,
+                      common.num_display_modes, common.display_modes,
+                      qdev_prop_display_mode, AppleGFXDisplayMode),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
 static void apple_gfx_pci_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
@@ -132,7 +139,7 @@  static void apple_gfx_pci_class_init(ObjectClass *klass, void *data)
     pci->class_id = PCI_CLASS_DISPLAY_OTHER;
     pci->realize = apple_gfx_pci_realize;
 
-    // TODO: Property for setting mode list
+    device_class_set_props(dc, apple_gfx_pci_properties);
 }
 
 static TypeInfo apple_gfx_pci_types[] = {
diff --git a/hw/display/apple-gfx.h b/hw/display/apple-gfx.h
index 39931fba65a..d2c6a14229a 100644
--- a/hw/display/apple-gfx.h
+++ b/hw/display/apple-gfx.h
@@ -9,6 +9,7 @@ 
 #import <ParavirtualizedGraphics/ParavirtualizedGraphics.h>
 #include "qemu/typedefs.h"
 #include "exec/memory.h"
+#include "hw/qdev-properties.h"
 #include "ui/surface.h"
 
 @class PGDeviceDescriptor;
@@ -20,6 +21,7 @@ 
 
 typedef QTAILQ_HEAD(, PGTask_s) PGTaskList;
 
+struct AppleGFXDisplayMode;
 struct AppleGFXMapMemoryJob;
 typedef struct AppleGFXState {
     MemoryRegion iomem_gfx;
@@ -31,6 +33,8 @@  typedef struct AppleGFXState {
     id<MTLCommandQueue> mtl_queue;
     bool cursor_show;
     QEMUCursor *cursor;
+    struct AppleGFXDisplayMode *display_modes;
+    uint32_t num_display_modes;
 
     /* For running PVG memory-mapping requests in the AIO context */
     QemuCond job_cond;
@@ -47,6 +51,12 @@  typedef struct AppleGFXState {
     id<MTLTexture> texture;
 } AppleGFXState;
 
+typedef struct AppleGFXDisplayMode {
+    uint16_t width_px;
+    uint16_t height_px;
+    uint16_t refresh_rate_hz;
+} AppleGFXDisplayMode;
+
 void apple_gfx_common_init(Object *obj, AppleGFXState *s, const char* obj_name);
 void apple_gfx_common_realize(AppleGFXState *s, PGDeviceDescriptor *desc,
                               Error **errp);
@@ -54,5 +64,7 @@  uintptr_t apple_gfx_host_address_for_gpa_range(uint64_t guest_physical,
                                                uint64_t length, bool read_only);
 void apple_gfx_await_bh_job(AppleGFXState *s, bool *job_done_flag);
 
+extern const PropertyInfo qdev_prop_display_mode;
+
 #endif
 
diff --git a/hw/display/apple-gfx.m b/hw/display/apple-gfx.m
index 46be9957f69..42b601329fb 100644
--- a/hw/display/apple-gfx.m
+++ b/hw/display/apple-gfx.m
@@ -28,9 +28,10 @@ 
 #include "qapi/error.h"
 #include "ui/console.h"
 
-static const PGDisplayCoord_t apple_gfx_modes[] = {
-    { .x = 1440, .y = 1080 },
-    { .x = 1280, .y = 1024 },
+static const AppleGFXDisplayMode apple_gfx_default_modes[] = {
+    { 1920, 1080, 60 },
+    { 1440, 1080, 60 },
+    { 1280, 1024, 60 },
 };
 
 /* This implements a type defined in <ParavirtualizedGraphics/PGDevice.h>
@@ -303,7 +304,6 @@  static void set_mode(AppleGFXState *s, uint32_t width, uint32_t height)
 static void create_fb(AppleGFXState *s)
 {
     s->con = graphic_console_init(NULL, 0, &apple_gfx_fb_ops, s);
-    set_mode(s, 1440, 1080);
 
     s->cursor_show = true;
 }
@@ -628,20 +628,25 @@  static void apple_gfx_register_task_mapping_handlers(AppleGFXState *s,
     return disp_desc;
 }
 
-static NSArray<PGDisplayMode*>* apple_gfx_prepare_display_mode_array(void)
+static NSArray<PGDisplayMode*>* apple_gfx_create_display_mode_array(
+    const AppleGFXDisplayMode display_modes[], uint32_t display_mode_count)
 {
-    PGDisplayMode *modes[ARRAY_SIZE(apple_gfx_modes)];
+    PGDisplayMode **modes = alloca(sizeof(modes[0]) * display_mode_count);
     NSArray<PGDisplayMode*>* mode_array = nil;
-    int i;
+    uint32_t i;
 
-    for (i = 0; i < ARRAY_SIZE(apple_gfx_modes); i++) {
+    for (i = 0; i < display_mode_count; i++) {
+        const AppleGFXDisplayMode *mode = &display_modes[i];
+        trace_apple_gfx_display_mode(i, mode->width_px, mode->height_px);
+        PGDisplayCoord_t mode_size = { mode->width_px, mode->height_px };
         modes[i] =
-            [[PGDisplayMode alloc] initWithSizeInPixels:apple_gfx_modes[i] refreshRateInHz:60.];
+            [[PGDisplayMode alloc] initWithSizeInPixels:mode_size
+                                        refreshRateInHz:mode->refresh_rate_hz];
     }
 
-    mode_array = [NSArray arrayWithObjects:modes count:ARRAY_SIZE(apple_gfx_modes)];
+    mode_array = [NSArray arrayWithObjects:modes count:display_mode_count];
 
-    for (i = 0; i < ARRAY_SIZE(apple_gfx_modes); i++) {
+    for (i = 0; i < display_mode_count; i++) {
         [modes[i] release];
         modes[i] = nil;
     }
@@ -679,6 +684,8 @@  void apple_gfx_common_realize(AppleGFXState *s, PGDeviceDescriptor *desc,
                               Error **errp)
 {
     PGDisplayDescriptor *disp_desc = nil;
+    const AppleGFXDisplayMode *display_modes = apple_gfx_default_modes;
+    int num_display_modes = ARRAY_SIZE(apple_gfx_default_modes);
 
     if (apple_gfx_mig_blocker == NULL) {
         error_setg(&apple_gfx_mig_blocker,
@@ -704,10 +711,106 @@  void apple_gfx_common_realize(AppleGFXState *s, PGDeviceDescriptor *desc,
     s->pgdisp = [s->pgdev newDisplayWithDescriptor:disp_desc
                                               port:0 serialNum:1234];
     [disp_desc release];
-    s->pgdisp.modeList = apple_gfx_prepare_display_mode_array();
+
+    if (s->display_modes != NULL && s->num_display_modes > 0) {
+        trace_apple_gfx_common_realize_modes_property(s->num_display_modes);
+        display_modes = s->display_modes;
+        num_display_modes = s->num_display_modes;
+    }
+    s->pgdisp.modeList =
+        apple_gfx_create_display_mode_array(display_modes, num_display_modes);
 
     create_fb(s);
 
     qemu_mutex_init(&s->job_mutex);
     qemu_cond_init(&s->job_cond);
 }
+
+static void apple_gfx_get_display_mode(Object *obj, Visitor *v,
+                                       const char *name, void *opaque,
+                                       Error **errp)
+{
+    Property *prop = opaque;
+    AppleGFXDisplayMode *mode = object_field_prop_ptr(obj, prop);
+    /* 3 uint16s (max 5 digits) and 2 separator characters + nul. */
+    static const size_t buffer_size = 5 * 3 + 2 + 1;
+
+    char buffer[buffer_size];
+    char *pos = buffer;
+
+    int rc = snprintf(buffer, buffer_size,
+                      "%"PRIu16"x%"PRIu16"@%"PRIu16,
+                      mode->width_px, mode->height_px,
+                      mode->refresh_rate_hz);
+    assert(rc < buffer_size);
+
+    visit_type_str(v, name, &pos, errp);
+}
+
+static void apple_gfx_set_display_mode(Object *obj, Visitor *v,
+                                       const char *name, void *opaque,
+                                       Error **errp)
+{
+    Property *prop = opaque;
+    AppleGFXDisplayMode *mode = object_field_prop_ptr(obj, prop);
+    Error *local_err = NULL;
+    const char *endptr;
+    char *str;
+    int ret;
+    unsigned int val;
+
+    visit_type_str(v, name, &str, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    endptr = str;
+
+    ret = qemu_strtoui(endptr, &endptr, 10, &val);
+    if (ret || val > UINT16_MAX || val == 0) {
+        error_setg(errp, "width in '%s' must be a decimal integer number "
+                   "of pixels in the range 1..65535", name);
+        goto out;
+    }
+    mode->width_px = val;
+    if (*endptr != 'x') {
+        goto separator_error;
+    }
+
+    ret = qemu_strtoui(endptr + 1, &endptr, 10, &val);
+    if (ret || val > UINT16_MAX || val == 0) {
+        error_setg(errp, "height in '%s' must be a decimal integer number "
+                   "of pixels in the range 1..65535", name);
+        goto out;
+    }
+    mode->height_px = val;
+    if (*endptr != '@') {
+        goto separator_error;
+    }
+
+    ret = qemu_strtoui(endptr + 1, &endptr, 10, &val);
+    if (ret) {
+        error_setg(errp, "refresh rate in '%s'"
+                   " must be a non-negative decimal integer (Hertz)", name);
+    }
+    mode->refresh_rate_hz = val;
+
+    goto out;
+
+separator_error:
+    error_setg(errp, "Each display mode takes the format "
+               "'<width>x<height>@<rate>'");
+out:
+    g_free(str);
+    return;
+}
+
+const PropertyInfo qdev_prop_display_mode = {
+    .name  = "display_mode",
+    .description =
+        "Display mode in pixels and Hertz, as <width>x<height>@<refresh-rate> "
+        "Example: 3840x2160@60",
+    .get   = apple_gfx_get_display_mode,
+    .set   = apple_gfx_set_display_mode,
+};
diff --git a/hw/display/trace-events b/hw/display/trace-events
index 214998312b9..2780239dbde 100644
--- a/hw/display/trace-events
+++ b/hw/display/trace-events
@@ -209,6 +209,8 @@  apple_gfx_cursor_set(uint32_t bpp, uint64_t width, uint64_t height) "bpp=%d widt
 apple_gfx_cursor_show(uint32_t show) "show=%d"
 apple_gfx_cursor_move(void) ""
 apple_gfx_common_init(const char *device_name, size_t mmio_size) "device: %s; MMIO size: %zu bytes"
+apple_gfx_common_realize_modes_property(uint32_t num_modes) "using %u modes supplied by 'display-modes' device property"
+apple_gfx_display_mode(uint32_t mode_idx, uint16_t width_px, uint16_t height_px) "mode %2"PRIu32": %4"PRIu16"x%4"PRIu16
 
 # apple-gfx-mmio.m
 apple_gfx_mmio_iosfc_read(uint64_t offset, uint64_t res) "offset=0x%"PRIx64" res=0x%"PRIx64