DRA821U: spi_sync_transfer read data always got 0

xiaodong liu

Part Number: DRA821U

Dear expert,

We are try to drive a SPI slave device through MCU_SPI1, we send cmd to the device, and we could get the data from slave when we check the oscilloscope, the MISO signal pin show the data already send out from deivce, the channel 2 is MISO signal at below figure. BUT, when we check the function spi_sync_transfer(), the rx data buf is 0, there is no data received! could you pleae help to figure out what's wrong with our below configuration and code ?

DTS:

mcu_spi1: spi@40310000 {

status="okay";

compatible = "ti,am654-mcspi","ti,omap4-mcspi";

reg = <0x0 0x40310000 0x0 0x400>;

interrupt-parent = <&gic500>;

interrupts = < GIC_SPI 849 IRQ_TYPE_LEVEL_HIGH>;

clocks = <&k3_clks 275 1>;

clock-names = "mcu_mcspi2";

power-domains = <&k3_pds 275 TI_SCI_PD_EXCLUSIVE>;

#address-cells = <1>;

#size-cells = <0>;

};

mcu_spi1_pins_default: mcu-spi1-pins-default {

pinctrl-single,pins = <

J721E_WKUP_IOPAD(0xc0, PIN_INPUT, 0) /* (B18) WKUP_GPIO0_0.MCU_SPI1_CLK */

J721E_WKUP_IOPAD(0xc4, PIN_OUTPUT, 0) /* (B19) WKUP_GPIO0_1.MCU_SPI1_D0 MOSI*/

J721E_WKUP_IOPAD(0xc8, PIN_INPUT, 0) /* (D14) WKUP_GPIO0_2.MCU_SPI1_D1 MISO*/

};

mcu_spi1_cs_pins_default: mcu-spi1-cs-pins-default {

pinctrl-single,pins = <

J721E_WKUP_IOPAD(0xcc, PIN_OUTPUT, 7) /* (B21) WKUP_GPIO0_3.MCU_SPI1_CS0 */

};

&mcu_spi1 {

pinctrl-names = "default";

pinctrl-0 = <&mcu_spi1_pins_default &mcu_spi1_cs_pins_default>;

cs-gpios = <&wkup_gpio0 3 GPIO_ACTIVE_LOW>;

ti,pindir-d0-out-d1-in;

status="okay";

sja1105@0 {

status="okay";

#address-cells = <1>;

#size-cells = <0>;

reg = < 0>;

compatible = "nxp,sja1105q";

spi-max-frequency = <4000000>;

spi-cpha;

};

CODE:

spi_sync_transfer(spi, xfers, 2 * num_chunks);

over 4 years ago

0 Brijesh Jadav over 4 years ago

TI__Guru**** 494835 points

Hi,

Could you please read the value of the pinmux register when Linux is booted up and confirmed that it set for the SPI output? Also are you setting up SPI in TX + RX mode? If it is just TX only mode, then RX will be empty. Can you check SPI register to confirm the settings?

Regards,

Brijesh

0 xiaodong liu over 4 years ago in reply to Brijesh Jadav

Prodigy 110 points

Hi,

we use spi-omap2-mcspi.c as the driver, there is the register set at function omap2_mcspi_transfer_one(), the code list below:

	chconf = mcspi_cached_chconf0(spi);
	chconf &= ~OMAP2_MCSPI_CHCONF_TRM_MASK;
	chconf &= ~OMAP2_MCSPI_CHCONF_TURBO;

	if (t->tx_buf == NULL)
		chconf |= OMAP2_MCSPI_CHCONF_TRM_RX_ONLY;
	else if (t->rx_buf == NULL)
		chconf |= OMAP2_MCSPI_CHCONF_TRM_TX_ONLY;

	if (cd && cd->turbo_mode && t->tx_buf == NULL) {
		/* Turbo mode is for more than one word */
		if (t->len > ((cs->word_len + 7) >> 3))
			chconf |= OMAP2_MCSPI_CHCONF_TURBO;
	}

	mcspi_write_chconf0(spi, chconf);

seems the code shall set the reg runtime.

or which register should we check ? what is the register name?

0 Brijesh Jadav over 4 years ago in reply to xiaodong liu

TI__Guru**** 494835 points

Hi,

Can you please MCSPI_CHCONF_ register for the SPI instance that you are using? In this register, bit12-13 are used to specify transmit/receive mode.

Regards,

Brijesh

0 xiaodong liu over 4 years ago in reply to Brijesh Jadav

Prodigy 110 points

Hi Brijesh

the register MCU_MCPSI1_CFG -> MCSPI_CHCONF_0 is 200603EC after the system powered up.

we perform "insmod sja1105.ko", there is one read command, then the register changed to 200633ED, seems the driver set the register correctly.

BRs,

Xiaodong

0 Brijesh Jadav over 4 years ago in reply to xiaodong liu

TI__Guru**** 494835 points

Hi xiaidong,

It does not look like. Because value 0x3 for bit12-13 is reserved value. It must be set to 0x0 in order to use TX+RX mode.

13-12

TRM

R/W

Transmit/receive modes
0h (R/W) = Transmit-and-receive mode
1h (R/W) = Receive-only mode
2h (R/W) = Transmit-only mode
3h (R/W) = Reserved

Regards,

Brijesh

0 xiaodong liu over 4 years ago in reply to Brijesh Jadav

Prodigy 110 points

Hi Rrijesh,

after set the register to 0x20160fed, the same result we got. any other clue could be checked?

BRs,

Xiaodong

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DRA821U: spi_sync_transfer read data always got 0