spi Overrun: RX data lost when "spi_sync_transfer" too long in kernel

[ABouc.1]

Hi,

I would like to make my STM32MP157 communicate with a FPGA in spi. I need to make long transfer (2-3 Mb) spi to get data acquired by the FPGA. But when I use the "spi_sync_transfer" function in my driver, I get the following kernel message:

#spi_stm32 4000b000.spi: Overrun: RX data lost

#spi0.0: SPI transfer failed: -5

# spi_master spi0: failed to transfer one message from queue

This driver works on an ompa3 platform.

I use a kernel linux 5.10, there is my device tree overlay :

/dts-v1/;
/plugin/;
&spi2 {
	ifsttarhf8ch: ifsttarhf8ch@0 {
		compatible = "ifsttar,ifsttarhf8ch";
		reg = <0>;
		spi-max-frequency = <100000000>;
		interrupt-parent = <&gpioi>;
		interrupts = <9 IRQ_TYPE_EDGE_RISING>; 
	};
};

and my device tree :

#include "stm32mp157.dtsi"
&spi2 {
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&spi2_pins_mx>;
	pinctrl-1 = <&spi2_sleep_pins_mx>;
	cs-gpios = <&gpiob 9 0>,
			   <&gpioi 1 0>,
			   <&gpiob 8 0> ;
	status = "okay";
 
	spidev2_1: spidev2_1@1{
		compatible = "rohm,dh2228fv";
		spi-max-frequency = <30000000>; 
		reg = <1>;
	};
	spidev2_2: spidev2_2@2{
		compatible = "rohm,dh2228fv";
		spi-max-frequency = <30000000>;
		reg = <2>;
	};
};

In my driver i use this code to read on the FPGA :

temp = CMD_READ(ADDR_BURST_DATA_RX); //fpga registry
transfer[0].tx_buf = &temp;
transfer[0].len = sizeof(temp);
transfer[1].rx_buf = data
transfer[1].len = sizeof(u16)*4095*8 // 4095 data * nb channel (8)
ret = spi_sync_transfer(spiHandler,&transfer[0],2);

Another problem, when I modify the "spi-max-frequency" field in the device tree, the clock frequency does not increase more than 12.5Mhz.

Sincerely

[PatrickF]

Hi @Arthur Bouché​ ,

I cannot answer for the overrun, maybe have a look to

https://wiki.st.com/stm32mpu/wiki/SPI_overview

https://wiki.st.com/stm32mpu/wiki/SPI_device_tree_configuration

Regarding the SPI frequency limited to 12.5MHz, this is probably because your clock tree define a too low frequency for SPI 'kernel' clock. The Linux driver compute the best he can do using peripheral constrains (e.g. SPI divider is 2, 4, 8 , etc...).

You could check the frequency received by your SPI by looking at spi2_k in clock summary.

See https://wiki.st.com/stm32mpu/wiki/Clock_overview#How_to_monitor_with_debugfs

E.g. In our starter package, on DK2, spi2_k is 11.29 MHz which should allows only up to 5.6MHz.

Regards.