Re: [PATCH net v5 1/4] net: ethernet: oa_tc6: Interrupt is active low, level triggered.

[<Parthiban.Veerasooran@microchip.com>]

Hi Selvamani,

I did a quick test by connecting Mikroe LAN8651 Click to a Raspberry Pi 
4 and shared the feedback below. Please let me know if you need any 
further details.

Test case 1: Single LAN8651 instance on RPI4

Setup:

RPI4 #1 + LAN8651 (IP: 192.168.10.101) <--- RPI4 #2 + EVB-LAN8670-USB 
(IP: 192.168.10.102)

Commands:

iperf3 -s -p 5001 <--- iperf3 -c 192.168.10.101 -u -b 9.4M -i 1 -t 0 -p 5001

Result:

No issues observed.

Test case 2: Two LAN8651 instances on the same RPI4

Setup:

RPI4 #1 + LAN8651 (IP: 192.168.10.101) <--- RPI4 #2 + EVB-LAN8670-USB 
(IP: 192.168.10.102)
RPI4 #1 + LAN8651 (IP: 192.168.20.101) <--- RPI4 #2 + EVB-LAN8670-USB 
(IP: 192.168.20.102)

Result:

Initially working fine with continuous "Receive buffer overflow" errors. 
This is expected, as both USB devices transmit at full speed while RPI4 
can handle the traffic only up to a maximum SPI frequency of 15 MHz. 
Eventually, the system crashed. The crash message was captured in the 
dmesg log,

[ 8276.676335] net_ratelimit: 2448 callbacks suppressed
[ 8276.676341] eth1: Receive buffer overflow error
[ 8276.676349] eth2: Receive buffer overflow error
[ 8276.680025] eth2: Receive buffer overflow error
[ 8276.680033] eth1: Receive buffer overflow error
[ 8276.683701] eth2: Receive buffer overflow error
[ 8276.683710] eth1: Receive buffer overflow error
[ 8276.687378] eth2: Receive buffer overflow error
[ 8276.687387] eth1: Receive buffer overflow error
[ 8276.691055] eth2: Receive buffer overflow error
[ 8276.691064] eth1: Receive buffer overflow error
[ 8281.662600] Unable to handle kernel NULL pointer dereference at 
virtual address 0000000000000074
[ 8281.670936] Mem abort info:
[ 8281.673747]   ESR = 0x0000000096000005
[ 8281.677544]   EC = 0x25: DABT (current EL), IL = 32 bits
[ 8281.682917]   SET = 0, FnV = 0
[ 8281.685997]   EA = 0, S1PTW = 0
[ 8281.689173]   FSC = 0x05: level 1 translation fault
[ 8281.694109] Data abort info:
[ 8281.697017]   ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
[ 8281.702571]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[ 8281.707680]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[ 8281.713056] user pgtable: 4k pages, 39-bit VAs, pgdp=0000000040a1d000
[ 8281.719578] [0000000000000074] pgd=0000000000000000, 
p4d=0000000000000000, pud=0000000000000000
[ 8281.728391] Internal error: Oops: 0000000096000005 [#1]  SMP
[ 8281.734115] Modules linked in: sch_fq lan865x_t1s(O) microchip_t1s(O) 
snd_seq_dummy snd_hrtimer snd_seq snd_seq_device rfcomm algif_hash 
aes_neon_bs algif_skcipher af_alg bnep binfmt_misc brcmfmac_cyw brcmfmac 
vc4 hci_uart brcmutil btbcm bluetooth v3d snd_soc_hdmi_codec bcm2835_isp 
cfg80211 rpi_hevc_dec bcm2835_codec(C) drm_exec bcm2835_v4l2(C) 
drm_display_helper ecdh_generic cec ecc bcm2835_mmal_vchiq gpu_sched 
videobuf2_vmalloc vc_sm_cma v4l2_mem2mem drm_dma_helper rfkill crc_ccitt 
drm_client_lib drm_shmem_helper videobuf2_dma_contig videobuf2_memops 
drm_kms_helper videobuf2_v4l2 snd_soc_core videodev raspberrypi_hwmon 
snd_bcm2835(C) snd_compress i2c_brcmstb snd_pcm_dmaengine snd_pcm 
videobuf2_common snd_timer mc raspberrypi_gpiomem spi_bcm2835 snd 
gpio_fan nvmem_rmem sch_fq_codel i2c_dev zram lz4_compress drm fuse 
drm_panel_orientation_quirks backlight nfnetlink
[ 8281.811847] CPU: 3 UID: 0 PID: 1759 Comm: irq/59-spi0.0 Tainted: G 
      C O        7.1.0-rc7-v8+ #1 PREEMPT
[ 8281.822067] Tainted: [C]=CRAP, [O]=OOT_MODULE
[ 8281.826473] Hardware name: Raspberry Pi 4 Model B Rev 1.4 (DT)
[ 8281.832377] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS 
BTYPE=--)
[ 8281.839427] pc : skb_put+0x14/0x80
[ 8281.842864] lr : oa_tc6_macphy_threaded_irq+0x428/0x880 [lan865x_t1s]
[ 8281.849386] sp : ffffffc083c4bd40
[ 8281.852735] x29: ffffffc083c4bd40 x28: 000000002020003e x27: 
ffffffe59e5609c8
[ 8281.859962] x26: ffffff8103d55080 x25: 0000000000000001 x24: 
ffffff8040566880
[ 8281.867187] x23: 0000000000000001 x22: 0000000000000000 x21: 
0000000000000000
[ 8281.874414] x20: 000000003e002020 x19: ffffff80405668a0 x18: 
00000000000b6748
[ 8281.881641] x17: ffffff9b64502000 x16: ffffffe59f08cef0 x15: 
1ae8add2c0a08935
[ 8281.888867] x14: b154d86008ee08e7 x13: b66a1ae8add2c0a0 x12: 
8935b154d86008ee
[ 8281.896093] x11: 00000000000000c0 x10: 0000000000001ae0 x9 : 
ffffffe590bb7918
[ 8281.903320] x8 : ffffff80493c1b40 x7 : 0000000000000004 x6 : 
ffffffffffffffff
[ 8281.910547] x5 : ffffffe59fb9d000 x4 : 0000000000000004 x3 : 
0000000000000000
[ 8281.917773] x2 : 0000000000000000 x1 : 0000000000000040 x0 : 
0000000000000000
[ 8281.925000] Call trace:
[ 8281.927468]  skb_put+0x14/0x80 (P)
[ 8281.930905]  oa_tc6_macphy_threaded_irq+0x428/0x880 [lan865x_t1s]
[ 8281.937073]  irq_thread_fn+0x34/0xc0
[ 8281.940686]  irq_thread+0x1a8/0x308
[ 8281.944212]  kthread+0x138/0x150
[ 8281.947472]  ret_from_fork+0x10/0x20
[ 8281.951089] Code: d503201f d503233f a9bf7bfd 910003fd (b9407406)
[ 8281.957258] ---[ end trace 0000000000000000 ]---
[ 8281.961969] genirq: exiting task "irq/59-spi0.0" (1759) is an active 
IRQ thread (irq 59)
[ 8282.080140] irq 59: nobody cared (try booting with the "irqpoll" option)
[ 8282.086344] CPU: 0 UID: 0 PID: 15 Comm: rcu_preempt Tainted: G      D 
  C O        7.1.0-rc7-v8+ #1 PREEMPT
[ 8282.086352] Tainted: [D]=DIE, [C]=CRAP, [O]=OOT_MODULE
[ 8282.086354] Hardware name: Raspberry Pi 4 Model B Rev 1.4 (DT)
[ 8282.086357] Call trace:
[ 8282.086359]  show_stack+0x20/0x38 (C)
[ 8282.086372]  dump_stack_lvl+0x60/0x80
[ 8282.086378]  dump_stack+0x18/0x24
[ 8282.086382]  __report_bad_irq+0x54/0xf0
[ 8282.086388]  note_interrupt+0x344/0x398
[ 8282.086393]  handle_irq_event+0xa4/0x110
[ 8282.086397]  handle_level_irq+0xe0/0x178
[ 8282.086401]  handle_irq_desc+0x3c/0x68
[ 8282.086407]  generic_handle_domain_irq+0x20/0x40
[ 8282.086413]  bcm2835_gpio_irq_handle_bank+0x180/0x1c8
[ 8282.086420]  bcm2835_gpio_irq_handler+0x88/0x188
[ 8282.086424]  handle_irq_desc+0x3c/0x68
[ 8282.086430]  generic_handle_domain_irq+0x20/0x40
[ 8282.086435]  gic_handle_irq+0x4c/0xe0
[ 8282.086438]  call_on_irq_stack+0x30/0x88
[ 8282.086444]  do_interrupt_handler+0x88/0x98
[ 8282.086447]  el1_interrupt+0x3c/0x60
[ 8282.086452]  el1h_64_irq_handler+0x18/0x30
[ 8282.086457]  el1h_64_irq+0x6c/0x70
[ 8282.086460]  _raw_spin_unlock_irq+0x10/0x60 (P)
[ 8282.086465]  rcu_gp_kthread+0x2f0/0x310
[ 8282.086471]  kthread+0x138/0x150
[ 8282.086476]  ret_from_fork+0x10/0x20
[ 8282.086481] handlers:
[ 8282.170193] lan8650 spi0.1: SPI transfer timed out
[ 8282.170591] [<0000000094f492f8>] oa_tc6_macphy_isr [lan865x_t1s]
[ 8282.174845] spi_master spi0: failed to transfer one message from queue
[ 8282.178435]  threaded [<000000008b769ba3>] oa_tc6_macphy_threaded_irq 
[lan865x_t1s]
[ 8282.178443] spi_master spi0: noqueue transfer failed

[ 8282.182578] Disabling IRQ #59
[ 8282.238458] lan8650 spi0.1 eth2: SPI data transfer failed: -110
[ 8282.244490] lan8650 spi0.1: Device interrupt disabled to avoid 
interrupt storm

Best regards,
Parthiban V

On 12/06/26 3:25 am, Selvamani Rajagopal via B4 Relay wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> From: Selvamani Rajagopal <Selvamani.Rajagopal@onsemi.com>
> 
> According OPEN Alliance 10BASET1x MAC-PHY Serial Interface
> specification, interrupt is active low, level triggered.
> 
> Code used edge triggered interrupt which has the risk of losing an
> interrupt on instances like when interrupt is disabled. Level
> triggered interrupt won't be deasserted unless handler runs and
> clear the interrupting conditions.
> 
> Interrupt handler mechanism is changed to threaded irq from
> interrupt handler and kernel thread waiting on work queue.
> Threaded irq mechanism is best suited for level triggered interrupt
> as it disables the interrupt until handler is run in thread level,
> while giving us an ability to have interrupt context handler to
> signal the threaded irq handler.
> 
> Introduced a logic to disable the device interrupt on error. Error
> could be due in data chunk's header and footer or SPI interface itself.
> This will avoid having repeated interrupts, in case the driver couldn't
> recover from the error condition with the available recovery mechanism.
> 
> Fixes: 2c6ce5354453 ("net: ethernet: oa_tc6: implement mac-phy interrupt")
> Signed-off-by: Selvamani Rajagopal <Selvamani.Rajagopal@onsemi.com>