An attempt to keep uboot logo before Linux displays system initialisation

[#1]

1.Test environment

Board: i.MX8MPlus, RM67199

BSP: uboot 2022.04, linux-6.1.1-1.0.1

2.Modification of uboot

 In uboot, you need comment the video_link_shut_down and dm_remove_devices_flags in announce_and_cleanup function.

#if defined(CONFIG_VIDEO_LINK)
	//video_link_shut_down();
#endif

	board_quiesce_devices();

	printf("\nStarting kernel ...%s\n\n", fake ?
		"(fake run for tracing)" : "");
	/*
	 * Call remove function of all devices with a removal flag set.
	 * This may be useful for last-stage operations, like cancelling
	 * of DMA operation or releasing device internal buffers.
	 */
// #ifndef CONFIG_POWER_DOMAIN
// 	dm_remove_devices_flags(DM_REMOVE_ACTIVE_ALL | DM_REMOVE_NON_VITAL);

// 	/* Remove all active vital devices next */
// 	dm_remove_devices_flags(DM_REMOVE_ACTIVE_ALL);
// #endif

	cleanup_before_linux();
}

 After doing this, the uboot logo will not be cleaned before Linux PM framework.

3.Modification of Linux

You need add  CONFIG_LOGO=n into defconfig file to disable kernel logo.

 3.1 Disable the power down of mediamix and mipi-dphy in gpcv2.c

Please add below code into the beginning of  imx_pgc_power_down function

if ((strcmp(genpd->name, "mipi-phy1") == 0) ||
			(strcmp(genpd->name, "mediamix") == 0))
	{
		return 0;
	}

 3.2 Only reset lcdif in the last call of drm framework

Please modify imx_lcdifv3_runtime_resume function like this. The imx_lcdifv3_runtime_resume function will be called two times, thus the lcdif will be reset two times.We can let it only reset last time,which before the rootfs mount.

bool rst = false; //////////////////////////////
static int imx_lcdifv3_runtime_resume(struct device *dev)
{
	int ret = 0;
	struct lcdifv3_soc *lcdifv3 = dev_get_drvdata(dev);

	if (unlikely(!atomic_read(&lcdifv3->rpm_suspended))) {
		dev_warn(lcdifv3->dev, "Unbalanced %s!\n", __func__);
		return 0;
	}

	if (!atomic_dec_and_test(&lcdifv3->rpm_suspended))
		return 0;

	/* set LCDIF QoS and cache */
	if (of_device_is_compatible(dev->of_node, "fsl,imx93-lcdif"))
		regmap_write(lcdifv3->gpr, 0xc, 0x3712);

	request_bus_freq(BUS_FREQ_HIGH);

	ret = lcdifv3_enable_clocks(lcdifv3);
	if (ret) {
		release_bus_freq(BUS_FREQ_HIGH);
		return ret;
	}

        //////////////////////////////
	if (rst)
	{
		/* clear sw_reset */
		writel(CTRL_SW_RESET, lcdifv3->base + LCDIFV3_CTRL_CLR);
		rst = false;
	}
	rst = true;
	//////////////////////////////

	/* enable plane FIFO panic */
	lcdifv3_enable_plane_panic(lcdifv3);

	return ret;
}

4.Conclusion

The uboot logo will be cleaned at log "imx-drm 1.0.0 20120507 for display-subsystem on minor 1".

The boot time of  systemd service on evk is very long. For weston.service, it needs 3 seconds.

From log here we test, the pcie and ethernet probe after drm system also cost about 1 second. If you want to reduce the boot time of other modules, you can try to reduce the system service and disable pcie/ethernet drivers if you don't need them.

[    2.505616] [drm] Initialized imx-drm 1.0.0 20120507 for display-subsystem on minor 1
[    2.620324] imx6q-pcie 33800000.pcie: iATU unroll: enabled
[    2.620335] imx6q-pcie 33800000.pcie: iATU regions: 4 ob, 4 ib, align 64K, limit 16G
[    2.720689] imx6q-pcie 33800000.pcie: PCIe Gen.1 x1 link up
[    2.820996] imx6q-pcie 33800000.pcie: PCIe Gen.2 x1 link up
[    2.821003] imx6q-pcie 33800000.pcie: Link up, Gen2
[    2.821010] imx6q-pcie 33800000.pcie: PCIe Gen.2 x1 link up
[    2.821112] imx6q-pcie 33800000.pcie: PCI host bridge to bus 0000:00
[    2.821119] pci_bus 0000:00: root bus resource [bus 00-ff]
[    2.821126] pci_bus 0000:00: root bus resource [io  0x0000-0xffff]
[    2.821133] pci_bus 0000:00: root bus resource [mem 0x18000000-0x1fefffff]
[    2.821161] pci 0000:00:00.0: [16c3:abcd] type 01 class 0x060400
[    2.821176] pci 0000:00:00.0: reg 0x10: [mem 0x00000000-0x000fffff]
[    2.821187] pci 0000:00:00.0: reg 0x38: [mem 0x00000000-0x0000ffff pref]
[    2.821232] pci 0000:00:00.0: supports D1
[    2.821237] pci 0000:00:00.0: PME# supported from D0 D1 D3hot D3cold
[    2.824664] pci 0000:01:00.0: [1b4b:2b42] type 00 class 0x020000
[    2.824725] pci 0000:01:00.0: reg 0x10: [mem 0x00000000-0x000fffff 64bit pref]
[    2.824761] pci 0000:01:00.0: reg 0x18: [mem 0x00000000-0x000fffff 64bit pref]
[    2.825066] pci 0000:01:00.0: supports D1 D2
[    2.825072] pci 0000:01:00.0: PME# supported from D0 D1 D3hot D3cold
[    2.835499] pci 0000:00:00.0: BAR 0: assigned [mem 0x18000000-0x180fffff]
[    2.835511] pci 0000:00:00.0: BAR 15: assigned [mem 0x18100000-0x182fffff pref]
[    2.835519] pci 0000:00:00.0: BAR 6: assigned [mem 0x18300000-0x1830ffff pref]
[    2.835530] pci 0000:01:00.0: BAR 0: assigned [mem 0x18100000-0x181fffff 64bit pref]
[    2.835561] pci 0000:01:00.0: BAR 2: assigned [mem 0x18200000-0x182fffff 64bit pref]
[    2.835590] pci 0000:00:00.0: PCI bridge to [bus 01-ff]
[    2.835598] pci 0000:00:00.0:   bridge window [mem 0x18100000-0x182fffff pref]
[    2.835899] pcieport 0000:00:00.0: PME: Signaling with IRQ 218
[    2.897767] Console: switching to colour frame buffer device 135x120
[    3.098361] imx-drm display-subsystem: [drm] fb0: imx-drmdrmfb frame buffer device
[    3.111239] pps pps0: new PPS source ptp0
[    3.316650] fec 30be0000.ethernet eth0: registered PHC device 0
[    3.323645] imx-dwmac 30bf0000.ethernet: IRQ eth_lpi not found
[    3.329593] imx-dwmac 30bf0000.ethernet: force_sf_dma_mode is ignored if force_thresh_dma_mode is set.
[    3.340074] imx-dwmac 30bf0000.ethernet: User ID: 0x10, Synopsys ID: 0x51
[    3.346883] imx-dwmac 30bf0000.ethernet:     DWMAC4/5
[    3.351684] imx-dwmac 30bf0000.ethernet: DMA HW capability register supported
[    3.358825] imx-dwmac 30bf0000.ethernet: RX Checksum Offload Engine supported
[    3.365966] imx-dwmac 30bf0000.ethernet: Wake-Up On Lan supported
[    3.372113] imx-dwmac 30bf0000.ethernet: Enable RX Mitigation via HW Watchdog Timer
[    3.379778] imx-dwmac 30bf0000.ethernet: Enabled L3L4 Flow TC (entries=8)
[    3.386573] imx-dwmac 30bf0000.ethernet: Enabled RFS Flow TC (entries=10)
[    3.393373] imx-dwmac 30bf0000.ethernet: Enabling HW TC (entries=256, max_off=256)
[    3.400950] imx-dwmac 30bf0000.ethernet: Using 34 bits DMA width
[    3.608045] xhci-hcd xhci-hcd.1.auto: xHCI Host Controller
[    3.613580] xhci-hcd xhci-hcd.1.auto: new USB bus registered, assigned bus number 1
[    3.621621] xhci-hcd xhci-hcd.1.auto: hcc params 0x0220fe6d hci version 0x110 quirks 0x0000002001010010
[    3.631059] xhci-hcd xhci-hcd.1.auto: irq 226, io mem 0x38200000
[    3.637197] xhci-hcd xhci-hcd.1.auto: xHCI Host Controller
[    3.642698] xhci-hcd xhci-hcd.1.auto: new USB bus registered, assigned bus number 2
[    3.650365] xhci-hcd xhci-hcd.1.auto: Host supports USB 3.0 SuperSpeed
[    3.657695] hub 1-0:1.0: USB hub found
[    3.661473] hub 1-0:1.0: 1 port detected
[    3.665669] usb usb2: We don't know the algorithms for LPM for this host, disabling LPM.
[    3.674445] hub 2-0:1.0: USB hub found
[    3.678220] hub 2-0:1.0: 1 port detected
[    3.683428] imx-cpufreq-dt imx-cpufreq-dt: cpu speed grade 7 mkt segment 2 supported-hw 0x80 0x4
[    3.693184] Hot alarm is canceled. GPU3D clock will return to 64/64
[    3.702683] sdhci-esdhc-imx 30b50000.mmc: Got CD GPIO
[    3.703346] mxc-mipi-csi2-sam 32e40000.csi: supply mipi-phy not found, using dummy regulator
[    3.716645] : mipi_csis_imx8mp_phy_reset, No remote pad found!
[    3.722602] mxc-mipi-csi2-sam 32e40000.csi: lanes: 2, hs_settle: 13, clk_settle: 2, wclk: 1, freq: 500000000
[    3.739353] mmc1: SDHCI controller on 30b50000.mmc [30b50000.mmc] using ADMA
[    3.752018] isi-m2m 32e00000.isi:m2m_device: Register m2m success for ISI.0
[    3.759172] cfg80211: Loading compiled-in X.509 certificates for regulatory database
[    3.768303] cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
[    3.787598] platform regulatory.0: Direct firmware load for regulatory.db failed with error -2
[    3.795171] ALSA device list:
[    3.796227] platform regulatory.0: Falling back to sysfs fallback for: regulatory.db
[    3.799186]   No soundcards found.
[    3.819630] EXT4-fs (mmcblk2p2): mounted filesystem with ordered data mode. Quota mode: none.
[    3.828212] VFS: Mounted root (ext4 filesystem) on device 179:2.
[    3.834944] devtmpfs: mounted