>
> Hey Markus,
>
> On 03.12.2021 15:38:38, Markus Mirevik wrote:
> > I have a problem I cant figure out underlaying cause to and maybe you
> > can help me.
>
> Let's move the discussion to the linux-can mailing list.
> (linux-can@xxxxxxxxxxxxxxx).
Sure.. buy replying to that address I hope 😊
>
> > I have custom board based on Beaglebone black.
> >
> > The CPU is a AM3358BZCZ100.
> > Connected to this is two mcp2518fd on one SPI line.
> > I'm currently running hardknott yocto build with kernel 5.10.79-yocto-tiny.
> >
> > The initialization of the mcp is fine:
> > [ 4.020952] mcp251xfd spi1.0 can0: MCP2518FD rev0.0 (+RX_INT -
> MAB_NO_WARN +CRC_REG +CRC_RX +CRC_TX +ECC -HD c:40.00MHz
> m:20.00MHz r:17.00MHz e:0.00MHz) successfully initialized.
> > [ 4.046274] mcp251xfd spi1.1 can1: MCP2518FD rev0.0 (+RX_INT -
> MAB_NO_WARN +CRC_REG +CRC_RX +CRC_TX +ECC -HD c:40.00MHz
> m:20.00MHz r:17.00MHz e:0.00MHz) successfully initialized.
>
> That looks good so far. Do you have connected the INT1 pin of the
> mcp2518fd to a GPIO of your board?
Yes I have.
>
> > Right now I have 3 other units talking on the canbus. Sending 3
> > messages every 10ms each. And that works great.
> >
> > But now to the problem. Every 5 minutes or so. (Not consistent,
> > sometimes earlier sometimes later ). I get a spike in CPU usage.
> >
> > It goes to 50% for sometimes a few seconds sometime a bit longer. In
> > between the peaks the CPU is idling around 2,5%.
>
> - Is this while there is communication on the CAN bus?
> - Can you compare the output of:
>
> | candump any,0:0,#FFFFFFFF -extA
>
> during this high load against output during normal operation.
>
Looks the same, but its a lot of messages. I compared 3 different seconds and both receive 594 or 596 messages / second .
> - Can you have a look at the IRQs and soft IRQs of your system during
> high load and during normal operation:
> | watch -n1 cat /proc/interrupts /proc/softirqs
Looks sort of the same to me the same to me,
With 53% load
Stop Start Sum /s
Time: 18:17:25 18:16:36 49 1
HI: 2 2 0,00 0,00
TIMER: 79941 79244 697,00 14,22
NET_TX: 1085 1075 10,00 0,20
NET_RX: 3131831 3103252 28579,00 583,24
BLOCK: 1224 1224 0,00 0,00
IRQ_POLL: 0 0 0,00 0,00
TASKLET: 1276 1276 0,00 0,00
SCHED: 0 0 0,00 0,00
HRTIMER: 0 0 0,00 0,00
RCU 173305 171765 1540,00 31,43
Normal 3% load
Stop Start Diff /s
Time: 18:21:24 18:20:35 49 1
HI: 2 2 0,00 0,00
TIMER: 83236 82552 684,00 13,96
NET_TX: 1133 1123 10,00 0,20
NET_RX: 3244121 3221392 22729,00 463,86
BLOCK: 1224 1224 0,00 0,00
IRQ_POLL: 0 0 0,00 0,00
TASKLET: 1276 1276 0,00 0,00
SCHED: 0 0 0,00 0,00
HRTIMER: 0 0 0,00 0,00
RCU 180684 179154 1530,00 31,22
A bit more NET_RX.. might that be an indicator?
>
> > Neither top or htop shows what process is using the CPU.
> > (irq/64-spi1.1 is stable around 14%)
>
> Please use htop, make sure you don't hide the kernel threads (Setup ->
> Display options -> Hide kernel threads), display detailed CPU usage (Setup ->
> Meters -> CPU [Text]). What kind of CPU usage ("sy", "ni", "hi", "si",...) do
> you have during high load?
Kernel threads is showing but I don’t seem to have the CPU[Text] option..
>
> > This only happens when I'm receiving on the can bus. If I bring can1
> > down it disappears right away. If I don't have anything connected it
> > doesn't happened.
>
> OK, that answers my first question. :)
>
> > The communication works great, no errors, no dropped, nothing that looks
> weird to me..
> > # ip -details -statistics link show can1
> > 6: can1: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP
> mode DEFAULT group default qlen 10
> > link/can promiscuity 0 minmtu 0 maxmtu 0
> > can state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0
> > bitrate 1000000 sample-point 0.750
> > tq 25 prop-seg 14 phase-seg1 15 phase-seg2 10 sjw 1
> > mcp251xfd: tseg1 2..256 tseg2 1..128 sjw 1..128 brp 1..256 brp-inc 1
> > mcp251xfd: dtseg1 1..32 dtseg2 1..16 dsjw 1..16 dbrp 1..256 dbrp-inc 1
> > clock 40000000
> > re-started bus-errors arbit-lost error-warn error-pass bus-off
> > 0 0 0 0 0 0 numtxqueues 1 numrxqueues 1
> gso_max_size 65536 gso_max_segs 65535
> > RX: bytes packets errors dropped missed mcast
> > 4298124 537270 0 0 0 0
> > TX: bytes packets errors dropped carrier collsns
> > 3 3 0 0 0 0
> >
> >
> > I have tested everything I can think of but I am not closer to a
> > answer to why this happens. Maybe you have some ideas? Or at least can
> > point me in the right direction?
>
> - Can you check if removing "microchip,rx-int-gpios" from you DT brings
> any difference?
Yes, it does not effect the 50% burst episodes. But it seems to use a bit more CPU when idle without the RX-int.
> - Can you send the complete mcp251xfd DT config snippet.
>
Yes, I can.
#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/interrupt-controller/irq.h>
&am33xx_pinmux{
pinctrl_spi1_pins: pinctrl_spi1_pins {
pinctrl-single,pins = <
AM33XX_IOPAD(0x990, PIN_INPUT | MUX_MODE3) /* (A13) mcasp0_aclkx.spi1_sclk */
AM33XX_IOPAD(0x994, PIN_INPUT | MUX_MODE3) /* (B13) mcasp0_fsx.spi1_d0 */
AM33XX_IOPAD(0x998, PIN_INPUT | MUX_MODE3) /* (D12) mcasp0_axr0.spi1_d1 */
AM33XX_IOPAD(0x96c, PIN_OUTPUT_PULLUP | MUX_MODE5) /* (E17) uart0_rtsn.spi1_cs0 CleANopen LEFT*/
AM33XX_IOPAD(0x9b0, PIN_OUTPUT_PULLUP | MUX_MODE4) /* (A15) xdma_event_intr0.spi1_cs1 SAWM CAN RIGHT*/
>;
};
can0_int_pins: can0_int_pins {
pinctrl-single,pins = <
/*CleANopen*/
AM33XX_IOPAD(0x89c, PIN_INPUT | MUX_MODE7) /* (T6) gpmc_be0n_cle.gpio2[5] nINT */
AM33XX_IOPAD(0x968, PIN_INPUT | MUX_MODE7) /* (E18) uart0_ctsn.gpio1[8] nINT1 */
>;
};
can1_int_pins: can1_int_pins {
pinctrl-single,pins = <
/*SAWM CAN*/
AM33XX_IOPAD(0x820, PIN_INPUT | MUX_MODE7) /* (U10) gpmc_ad8.gpio0[22] nINT */
AM33XX_IOPAD(0x8c8, PIN_INPUT | MUX_MODE7) /* (U3) lcd_data10.gpio2[16] nINT1 */
AM33XX_IOPAD(0x8cc, PIN_INPUT | MUX_MODE7) /* (U4) lcd_data11.gpio2[17] nINT0 NOT USED */
>;
};
};
/{
/* external 40M oscillator of mcp2518fd on SPI1.0 */
mcp2518fd_can0_osc: mcp2518fd_can0_osc {
compatible = "fixed-clock";
#clock-cells = <0>;
clock-frequency = <40000000>;
};
};
/{
/* external 40M oscillator of mcp2518fd on SPI1.1 */
mcp2518fd_can1_osc: mcp2518fd_can1_osc {
compatible = "fixed-clock";
#clock-cells = <0>;
clock-frequency = <40000000>;
};
};
/* the spi config of the can-controller itself binding everything together */
&spi1{
#address-cells = <1>;
#size-cells = <0>;
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_spi1_pins>;
/*CleANopen*/
can@0 {
compatible = "microchip,mcp2518fd";
reg = <0>;
clocks = <&mcp2518fd_can0_osc>;
pinctrl-names = "default";
pinctrl-0 = <&can0_int_pins>;
spi-max-frequency = <20000000>;
interrupts-extended = <&gpio2 5 IRQ_TYPE_LEVEL_LOW>;
microchip,rx-int-gpios = <&gpio1 8 GPIO_ACTIVE_LOW>;
};
can@1 {
compatible = "microchip,mcp2518fd";
reg = <1>;
clocks = <&mcp2518fd_can1_osc>;
pinctrl-names = "default";
pinctrl-0 = <&can1_int_pins>;
spi-max-frequency = <20000000>;
interrupts-extended = <&gpio0 22 IRQ_TYPE_LEVEL_LOW>;
microchip,rx-int-gpios = <&gpio2 16 GPIO_ACTIVE_LOW>;
};
};
Thank you for your time!
Markus
> regards,
> Marc
>
> --
> Pengutronix e.K. | Marc Kleine-Budde |
> Embedded Linux | https://www.pengutronix.de |
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