text: From 5357e5991f09f78e945b3adcc5db0ebfa1766dc1 Mon Sep 17 00:00:00 2001
  From: Dave Stevenson <dave.stevenson@raspberrypi.org>
  Date: Tue, 9 Apr 2019 12:37:28 +0100
  Subject: [PATCH] drm: vc4: Query the display ID for each display in
   FKMS
  
  Replace the hard coded list of display IDs for a mailbox call
  that returns the display ID for each display that has been
  detected.
  
  Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
  ---
   drivers/gpu/drm/vc4/vc4_firmware_kms.c     | 16 +++++++++++++---
   include/soc/bcm2835/raspberrypi-firmware.h |  1 +
   2 files changed, 14 insertions(+), 3 deletions(-)
  
  --- a/drivers/gpu/drm/vc4/vc4_firmware_kms.c
  +++ b/drivers/gpu/drm/vc4/vc4_firmware_kms.c
  @@ -944,7 +944,7 @@ static int vc4_fkms_bind(struct device *
   	struct vc4_crtc **crtc_list;
   	u32 num_displays, display_num;
   	int ret;
  -	const u32 display_num_lookup[] = {2, 7, 1};
  +	u32 display_id;
   
   	vc4->firmware_kms = true;
   
  @@ -983,8 +983,18 @@ static int vc4_fkms_bind(struct device *
   		return -ENOMEM;
   
   	for (display_num = 0; display_num < num_displays; display_num++) {
  -		ret = vc4_fkms_create_screen(dev, drm, display_num,
  -					     display_num_lookup[display_num],
  +		display_id = display_num;
  +		ret = rpi_firmware_property(vc4->firmware,
  +					    RPI_FIRMWARE_FRAMEBUFFER_GET_DISPLAY_ID,
  +					    &display_id, sizeof(display_id));
  +		/* FIXME: Determine the correct error handling here.
  +		 * Should we fail to create the one "screen" but keep the
  +		 * others, or fail the whole thing?
  +		 */
  +		if (ret)
  +			DRM_ERROR("Failed to get display id %u\n", display_num);
  +
  +		ret = vc4_fkms_create_screen(dev, drm, display_num, display_id,
   					     &crtc_list[display_num]);
   		if (ret)
   			DRM_ERROR("Oh dear, failed to create display %u\n",
  --- a/include/soc/bcm2835/raspberrypi-firmware.h
  +++ b/include/soc/bcm2835/raspberrypi-firmware.h
  @@ -114,6 +114,7 @@ enum rpi_firmware_property_tag {
   	RPI_FIRMWARE_FRAMEBUFFER_GET_TOUCHBUF =               0x0004000f,
   	RPI_FIRMWARE_FRAMEBUFFER_GET_GPIOVIRTBUF =            0x00040010,
   	RPI_FIRMWARE_FRAMEBUFFER_RELEASE =                    0x00048001,
  +	RPI_FIRMWARE_FRAMEBUFFER_GET_DISPLAY_ID =             0x00040016,
   	RPI_FIRMWARE_FRAMEBUFFER_SET_DISPLAY_NUM =            0x00048013,
   	RPI_FIRMWARE_FRAMEBUFFER_GET_NUM_DISPLAYS =           0x00040013,
   	RPI_FIRMWARE_FRAMEBUFFER_GET_DISPLAY_SETTINGS =       0x00040014,
  