因此，我需要一些有关如何使spidev在内核init的开始运行的指导。我正在使用ILI9341显示器，该显示器连接到使用SPI驱动的Pocketbeagle。问题是，我需要在引导过程中将图像“发送”到显示器。为此，我需要在启动过程的最开始就启动spidev，但我不确定是什么进程启动了spidev。我不确定这是系统进程还是其他进程启动的。
这是我的设备树声明spidev（原始版本：am335x-pocketbeagle.dts）：
&spi0 {
#address-cells = <1>;
#size-cells = <0>;
status = "okay";
channel@0 {
#address-cells = <1>;
#size-cells = <0>;
compatible = "spidev";
reg = <0>;
spi-max-frequency = <100000000>;
};
channel@1 {
#address-cells = <1>;
#size-cells = <0>;
compatible = "spidev";
reg = <1>;
spi-max-frequency = <100000000>;
status = "disabled";
};
};
&spi1 {
#address-cells = <1>;
#size-cells = <0>;
status = "okay";
channel@0 {
#address-cells = <1>;
#size-cells = <0>;
compatible = "spidev";
reg = <0>;
spi-max-frequency = <100000000>;
};
channel@1 {
#address-cells = <1>;
#size-cells = <0>;
compatible = "spidev";
reg = <1>;
spi-max-frequency = <100000000>;
};
};
这是启动过程的开始（此处仅显示前几秒钟）：
U-Boot SPL 2018.01-dirty (May 06 2018 - 17:12:35)
Trying to boot from MMC1
U-Boot 2018.01-dirty (May 06 2018 - 17:12:35 -0400)
CPU : AM335X-GP rev 2.1
I2C: ready
DRAM: 512 MiB
No match for driver 'omap_hsmmc'
No match for driver 'omap_hsmmc'
Some drivers were not found
Reset Source: Power-on reset has occurred.
MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1
Using default environment
Model: BeagleBoard.org PocketBeagle
<ethaddr> not set. Validating first E-fuse MAC
Net: usb_ether
Press SPACE to abort autoboot in 2 seconds
board_name=[A335PBGL] ...
switch to partitions #0, OK
mmc0 is current device
SD/MMC found on device 0
** Bad device 0:2 0x82000000 **
** Bad device 0:2 0x82000000 **
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
gpio: pin 56 (gpio 56) value is 0
gpio: pin 55 (gpio 55) value is 0
gpio: pin 54 (gpio 54) value is 0
gpio: pin 53 (gpio 53) value is 1
switch to partitions #0, OK
mmc0 is current device
gpio: pin 54 (gpio 54) value is 1
Checking for: /uEnv.txt ...
Checking for: /boot.scr ...
Checking for: /boot/boot.scr ...
Checking for: /boot/uEnv.txt ...
gpio: pin 55 (gpio 55) value is 1
24 bytes read in 15 ms (1000 Bytes/s)
Loaded environment from /boot/uEnv.txt
Checking if uname_r is set in /boot/uEnv.txt...
gpio: pin 56 (gpio 56) value is 1
Running uname_boot ...
loading /boot/vmlinuz-4.4.113-ti-r149 ...
9431560 bytes read in 612 ms (14.7 MiB/s)
loading /boot/dtbs/4.4.113-ti-r149/am335x-pocketbeagle.dtb ...
130113 bytes read in 84 ms (1.5 MiB/s)
uboot_overlays: add [enable_uboot_overlays=1] to /boot/uEnv.txt to enable...
debug: [console=ttyO0,115200n8 root=/dev/mmcblk0p1 ro rootfstype=ext4 rootwait] ...
debug: [bootz 0x82000000 - 0x88000000] ...
## Flattened Device Tree blob at 88000000
Booting using the fdt blob at 0x88000000
Loading Device Tree to 8ffdd000, end 8ffffc40 ... OK
Starting kernel ...
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Initializing cgroup subsys cpuset
[ 0.000000] Initializing cgroup subsys cpu
[ 0.000000] Initializing cgroup subsys cpuacct
[ 0.000000] Linux version 4.4.113-ti-r149 (luis@luis) (gcc version 5.5.0 (Lin aro GCC 5.5-2017.10) ) #2 SMP Fri Jun 29 16:50:45 EDT 2018
[ 0.000000] CPU: ARMv7 Processor [413fc082] revision 2 (ARMv7), cr=10c5387d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instructio n cache
[ 0.000000] Machine model: TI AM335x PocketBeagle
[ 0.000000] cma: Reserved 48 MiB at 0x9c800000
[ 0.000000] Memory policy: Data cache writeback
[ 0.000000] CPU: All CPU(s) started in SVC mode.
[ 0.000000] AM335X ES2.1 (sgx neon )
[ 0.000000] PERCPU: Embedded 13 pages/cpu @df8f2000 s24192 r8192 d20864 u5324 8
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pag es: 129408
[ 0.000000] Kernel command line: console=ttyO0,115200n8 root=/dev/mmcblk0p1 r o rootfstype=ext4 rootwait
[ 0.000000] PID hash table entries: 2048 (order: 1, 8192 bytes)
[ 0.000000] Dentry cache hash table entries: 65536 (order: 6, 262144 bytes)
[ 0.000000] Inode-cache hash table entries: 32768 (order: 5, 131072 bytes)
[ 0.000000] Memory: 448072K/522240K available (12533K kernel code, 1016K rwda ta, 4064K rodata, 824K init, 857K bss, 25016K reserved, 49152K cma-reserved, 0K highmem)
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB)
[ 0.000000] fixmap : 0xffc00000 - 0xfff00000 (3072 kB)
[ 0.000000] vmalloc : 0xe0800000 - 0xff800000 ( 496 MB)
[ 0.000000] lowmem : 0xc0000000 - 0xe0000000 ( 512 MB)
[ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB)
[ 0.000000] modules : 0xbf000000 - 0xbfe00000 ( 14 MB)
[ 0.000000] .text : 0xc0008000 - 0xc103d760 (16598 kB)
[ 0.000000] .init : 0xc103e000 - 0xc110c000 ( 824 kB)
[ 0.000000] .data : 0xc110c000 - 0xc120a0e8 (1017 kB)
[ 0.000000] .bss : 0xc120d000 - 0xc12e355c ( 858 kB)
[ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.000000] Hierarchical RCU implementation.
[ 0.000000] Build-time adjustment of leaf fanout to 32.
[ 0.000000] RCU restricting CPUs from NR_CPUS=2 to nr_cpu_ids=1.
[ 0.000000] RCU: Adjusting geometry for rcu_fanout_leaf=32, nr_cpu_ids=1
[ 0.000000] NR_IRQS:16 nr_irqs:16 16
[ 0.000000] IRQ: Found an INTC at 0xfa200000 (revision 5.0) with 128 interrup ts
[ 0.000000] OMAP clockevent source: timer2 at 24000000 Hz
[ 0.000022] sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 89478 484971ns
[ 0.000048] clocksource: timer1: mask: 0xffffffff max_cycles: 0xffffffff, max _idle_ns: 79635851949 ns
[ 0.000061] OMAP clocksource: timer1 at 24000000 Hz
[ 0.001914] clocksource_probe: no matching clocksources found
[ 0.002223] Console: colour dummy device 80x30
[ 0.002254] WARNING: Your 'console=ttyO0' has been replaced by 'ttyS0'
[ 0.002262] This ensures that you still see kernel messages. Please
[ 0.002268] update your kernel commandline.
[ 0.002289] Calibrating delay loop... 995.32 BogoMIPS (lpj=1990656)
[ 0.021215] pid_max: default: 32768 minimum: 301
[ 0.021365] Security Framework initialized
[ 0.021380] Yama: becoming mindful.
[ 0.021418] AppArmor: AppArmor disabled by boot time parameter
[ 0.021590] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.021603] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.022464] Initializing cgroup subsys io
[ 0.022497] Initializing cgroup subsys memory
[ 0.022543] Initializing cgroup subsys devices
[ 0.022561] Initializing cgroup subsys freezer
[ 0.022578] Initializing cgroup subsys net_cls
[ 0.022592] Initializing cgroup subsys perf_event
[ 0.022607] Initializing cgroup subsys net_prio
[ 0.022630] Initializing cgroup subsys pids
[ 0.022688] CPU: Testing write buffer coherency: ok
[ 0.022747] ftrace: allocating 37522 entries in 111 pages
[ 0.128715] CPU0: thread -1, cpu 0, socket -1, mpidr 0
[ 0.128838] Setting up static identity map for 0x80008280 - 0x800082e0
[ 0.133343] Brought up 1 CPUs
[ 0.133369] SMP: Total of 1 processors activated (995.32 BogoMIPS).
[ 0.133377] CPU: All CPU(s) started in SVC mode.
[ 0.134975] devtmpfs: initialized
[ 0.172782] VFP support v0.3: implementor 41 architecture 3 part 30 variant c rev 3
[ 0.223366] omap_hwmod: debugss: _wait_target_disable failed
[ 0.277491] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, ma x_idle_ns: 7645041785100000 ns
[ 0.277527] futex hash table entries: 256 (order: 2, 16384 bytes)
[ 0.281782] xor: measuring software checksum speed
[ 0.321202] arm4regs : 1219.000 MB/sec
[ 0.361191] 8regs : 957.000 MB/sec
[ 0.401188] 32regs : 1089.000 MB/sec
[ 0.441187] neon : 1725.000 MB/sec
[ 0.441195] xor: using function: neon (1725.000 MB/sec)
[ 0.441228] pinctrl core: initialized pinctrl subsystem
[ 0.442711] NET: Registered protocol family 16
[ 0.445513] DMA: preallocated 256 KiB pool for atomic coherent allocations
[ 0.446456] cpuidle: using governor ladder
[ 0.446477] cpuidle: using governor menu
[ 0.452463] OMAP GPIO hardware version 0.1
[ 0.475562] No ATAGs?
[ 0.475601] hw-breakpoint: debug architecture 0x4 unsupported.
[ 0.476766] omap4_sram_init:Unable to allocate sram needed to handle errata I 688
[ 0.476789] omap4_sram_init:Unable to get sram pool needed to handle errata I 688
[ 0.557214] raid6: neonx2 gen() 1887 MB/s
[ 0.625198] raid6: neonx2 xor() 1161 MB/s
[ 0.625207] raid6: using algorithm neonx2 gen() 1887 MB/s
[ 0.625214] raid6: .... xor() 1161 MB/s, rmw enabled
[ 0.625221] raid6: using intx1 recovery algorithm
[ 0.635476] edma 49000000.edma: TI EDMA DMA engine driver
[ 0.640859] vgaarb: loaded
[ 0.641610] SCSI subsystem initialized
[ 0.642367] usbcore: registered new interface driver usbfs
[ 0.642449] usbcore: registered new interface driver hub
[ 0.642560] usbcore: registered new device driver usb
[ 0.643413] omap_i2c 44e0b000.i2c: could not find pctldev for node /ocp/l4_wk up@44c00000/scm@210000/pinmux@800/pinmux_i2c0_pins, deferring probe
[ 0.644286] omap_i2c 4802a000.i2c: bus 1 rev0.11 at 400 kHz
[ 0.644967] omap_i2c 4819c000.i2c: bus 2 rev0.11 at 400 kHz
[ 0.645404] media: Linux media interface: v0.10
[ 0.645482] Linux video capture interface: v2.00
[ 0.645611] pps_core: LinuxPPS API ver. 1 registered
[ 0.645620] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giome tti <giometti@linux.it>
[ 0.645655] PTP clock support registered
[ 0.646615] omap-mailbox 480c8000.mailbox: omap mailbox rev 0x400
[ 0.648938] NetLabel: Initializing
[ 0.648955] NetLabel: domain hash size = 128
[ 0.648961] NetLabel: protocols = UNLABELED CIPSOv4
[ 0.649029] NetLabel: unlabeled traffic allowed by default
[ 0.649769] clocksource: Switched to clocksource timer1
[ 0.773340] NET: Registered protocol family 2
[ 0.774347] TCP established hash table entries: 4096 (order: 2, 16384 bytes)
[ 0.774397] TCP bind hash table entries: 4096 (order: 3, 32768 bytes)
[ 0.774456] TCP: Hash tables configured (established 4096 bind 4096)
[ 0.774539] UDP hash table entries: 256 (order: 1, 8192 bytes)
[ 0.774560] UDP-Lite hash table entries: 256 (order: 1, 8192 bytes)
[ 0.774925] NET: Registered protocol family 1
[ 0.775551] RPC: Registered named UNIX socket transport module.
[ 0.775567] RPC: Registered udp transport module.
[ 0.775574] RPC: Registered tcp transport module.
[ 0.775580] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 0.776750] hw perfevents: enabled with armv7_cortex_a8 PMU driver, 5 counter s available
[ 0.780201] audit: initializing netlink subsys (disabled)
[ 0.780300] audit: type=2000 audit(0.712:1): initialized
[ 0.790964] zbud: loaded
[ 0.791713] VFS: Disk quotas dquot_6.6.0
[ 0.791995] VFS: Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[ 0.795073] NFS: Registering the id_resolver key type
[ 0.795149] Key type id_resolver registered
[ 0.795157] Key type id_legacy registered
[ 0.795187] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[ 0.795579] fuse init (API version 7.23)
[ 0.796227] SGI XFS with ACLs, security attributes, realtime, no debug enable d
[ 0.805645] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 2 47)
[ 0.806079] io scheduler noop registered
[ 0.806100] io scheduler deadline registered
[ 0.806175] io scheduler cfq registered (default)
[ 0.808070] pinctrl-single 44e10800.pinmux: 142 pins at pa f9e10800 size 568
[ 0.809173] gpio-of-helper ocp:cape-universal: Allocated GPIO id=0
[ 0.809332] gpio-of-helper ocp:cape-universal: Allocated GPIO id=1
[ 0.809521] gpio-of-helper ocp:cape-universal: Allocated GPIO id=2
[ 0.809670] gpio-of-helper ocp:cape-universal: Allocated GPIO id=3
[ 0.810219] gpio-of-helper ocp:cape-universal: Allocated GPIO id=4
[ 0.810400] gpio-of-helper ocp:cape-universal: Allocated GPIO id=5
[ 0.810547] gpio-of-helper ocp:cape-universal: Allocated GPIO id=6
[ 0.810691] gpio-of-helper ocp:cape-universal: Allocated GPIO id=7
[ 0.810844] gpio-of-helper ocp:cape-universal: Allocated GPIO id=8
[ 0.811050] gpio-of-helper ocp:cape-universal: Allocated GPIO id=9
[ 0.811224] gpio-of-helper ocp:cape-universal: Allocated GPIO id=10
[ 0.811392] gpio-of-helper ocp:cape-universal: Allocated GPIO id=11
[ 0.811539] gpio-of-helper ocp:cape-universal: Allocated GPIO id=12
[ 0.811692] gpio-of-helper ocp:cape-universal: Allocated GPIO id=13
[ 0.811838] gpio-of-helper ocp:cape-universal: Allocated GPIO id=14
[ 0.811988] gpio-of-helper ocp:cape-universal: Allocated GPIO id=15
[ 0.812144] gpio-of-helper ocp:cape-universal: Allocated GPIO id=16
[ 0.812293] gpio-of-helper ocp:cape-universal: Allocated GPIO id=17
[ 0.812445] gpio-of-helper ocp:cape-universal: Allocated GPIO id=18
[ 0.812598] gpio-of-helper ocp:cape-universal: Allocated GPIO id=19
[ 0.812752] gpio-of-helper ocp:cape-universal: Allocated GPIO id=20
[ 0.812907] gpio-of-helper ocp:cape-universal: Allocated GPIO id=21
[ 0.813055] gpio-of-helper ocp:cape-universal: Allocated GPIO id=22
[ 0.813189] gpio-of-helper ocp:cape-universal: Allocated GPIO id=23
[ 0.813332] gpio-of-helper ocp:cape-universal: Allocated GPIO id=24
[ 0.813467] gpio-of-helper ocp:cape-universal: Allocated GPIO id=25
[ 0.813602] gpio-of-helper ocp:cape-universal: Allocated GPIO id=26
[ 0.813842] gpio-of-helper ocp:cape-universal: Allocated GPIO id=27
[ 0.814192] gpio-of-helper ocp:cape-universal: Allocated GPIO id=28
[ 0.814350] gpio-of-helper ocp:cape-universal: Allocated GPIO id=29
[ 0.814491] gpio-of-helper ocp:cape-universal: Allocated GPIO id=30
[ 0.814629] gpio-of-helper ocp:cape-universal: Allocated GPIO id=31
[ 0.814774] gpio-of-helper ocp:cape-universal: Allocated GPIO id=32
[ 0.814911] gpio-of-helper ocp:cape-universal: Allocated GPIO id=33
[ 0.815048] gpio-of-helper ocp:cape-universal: Allocated GPIO id=34
[ 0.815196] gpio-of-helper ocp:cape-universal: Allocated GPIO id=35
[ 0.815338] gpio-of-helper ocp:cape-universal: Allocated GPIO id=36
[ 0.815485] gpio-of-helper ocp:cape-universal: Allocated GPIO id=37
[ 0.815624] gpio-of-helper ocp:cape-universal: Allocated GPIO id=38
[ 0.815762] gpio-of-helper ocp:cape-universal: Allocated GPIO id=39
[ 0.815909] gpio-of-helper ocp:cape-universal: Allocated GPIO id=40
[ 0.816053] gpio-of-helper ocp:cape-universal: Allocated GPIO id=41
[ 0.816194] gpio-of-helper ocp:cape-universal: Allocated GPIO id=42
[ 0.816343] gpio-of-helper ocp:cape-universal: Allocated GPIO id=43
[ 0.816354] gpio-of-helper ocp:cape-universal: ready
[ 0.822156] wkup_m3_ipc 44e11324.wkup_m3_ipc: could not get rproc handle
[ 0.824170] Serial: 8250/16550 driver, 6 ports, IRQ sharing disabled
[ 0.827881] 44e09000.serial: ttyS0 at MMIO 0x44e09000 (irq = 158, base_baud = 3000000) is a 8250
[ 1.921701] console [ttyS0] enabled
诸如GPIO和I2C之类的“重要”东西似乎在启动过程的开始就在运行。我如何用spidev做同样的事情？
我不清楚启动过程中在哪里声明了Pocketbeagle的设备树？ / dev / spidev在引导过程中的哪里可用？我该如何使它更早开始？
答案 0 :(得分：1)
将@sawdust和我的评论总结为一个答案：
bootdelay to 0 or -2 in U-Boot Env