Hello I have performance problems with mcp2518fd. I have custom board based of beagleboard black. (Sitara am335x) using two mcp2518fd. The can communication uses a lot of CPU. irq/64-spi1.1 uses around ~20% at 1000 can messages/s. I have several questions but I'll start with the most confusing. I have found that every can messages fires two interrupts on my board. I have tested this in several ways. If I send one normal can message the counter in /proc/interrupts is increased twice. I have also put some printouts in mcp251xfd-core.c that confirms that mcp251xfd_irq() is run twice and the second time intf_pending is 0. And for testing purposes I changed the interrupt config to trigger on falling edge instead of level and with this configured there is only one interrupt fired. But I guess this will risk locking the interrupt line low if an edge isn't detected. I have tried both with rx-int active and inactive. My scope shows really nice signals and that rx-int and int is deactivated simultaneous on incoming frames. I'm testing by sending messages from my computer through a can dongle. The board is currently running Linux 5.10.79-yocto-tiny #1 SMP Tue Nov 16 03:57:43 UTC 2021 armv7l armv7l armv7l GNU/Linux I've also tested updating the driver to the one from https://github.com/marckleinebudde/linux.git from 2021-12-29 with the same result (IRQ handler run twice). I am profoundly confused by this issue and I can not figure out why it's happening. My understanding is that since the IRQ handler is loaded with IRQF_ONESHOT the irq line should be masked until mcp251xfd_irq() returns. Since mcp251xfd_irq() checks that !rx_pending before exiting the int signal must be high. And the interrupt should not fire again... Result from init: [ 4.003029] 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. [ 4.028220] 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. This is the current dtsi part for the canFD chips. (With rx-pin removed on one of the devices and trigger on edge on the other for debugging purposes). #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_PULLUP | MUX_MODE7) /* (T6) gpmc_be0n_cle.gpio2[5] nINT */ AM33XX_IOPAD(0x968, PIN_INPUT_PULLUP | MUX_MODE7) /* (E18) uart0_ctsn.gpio1[8] nINT1 */ >; }; can1_int_pins: can1_int_pins { pinctrl-single,pins = < /*SAWM CAN*/ AM33XX_IOPAD(0x820, PIN_INPUT_PULLUP | MUX_MODE7) /* (U10) gpmc_ad8.gpio0[22] nINT */ AM33XX_IOPAD(0x8c8, PIN_INPUT_PULLUP | MUX_MODE7) /* (U3) lcd_data10.gpio2[16] nINT1 */ AM33XX_IOPAD(0x8cc, PIN_INPUT_PULLUP | 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_EDGE_FALLING>; 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>; }; }; BR Markus Mirevik
