9160dk external flash operation address length issue

Question

The default setting for the external flash chip of 9160dk appears to be 64m, but when used, the log display only shows 8m, and only the part within 8m can be used,

mx25r64: mx25r6435f@1 {
		compatible = "jedec,spi-nor";
		status = "disabled";
		reg = <1>; 
		spi-max-frequency = <8000000>;
		jedec-id = [c2 28 17];
		sfdp-bfp = [
			e5 20 f1 ff  ff ff ff 03  44 eb 08 6b  08 3b 04 bb
			ee ff ff ff  ff ff 00 ff  ff ff 00 ff  0c 20 0f 52
			10 d8 00 ff  23 72 f5 00  82 ed 04 cc  44 83 48 44
			30 b0 30 b0  f7 c4 d5 5c  00 be 29 ff  f0 d0 ff ff
		];
		size = <67108864>;
		has-dpd;
		t-enter-dpd = <10000>;
		t-exit-dpd = <35000>;
	};
	
	<inf> spi_nor: mx25r6435f@1: 8 MiBy flash

Then I set the chip size to 8 times that of 64m in order to use all 64m of flash properly

&mx25r64 {
    status = "okay";
	size = <0x20000000>;
    sfdp-bfp = [
			e5 20 f1 ff  ff ff ff 1f  44 eb 08 6b  08 3b 04 bb
			ee ff ff ff  ff ff 00 ff  ff ff 00 ff  0c 20 0f 52
			10 d8 00 ff  23 72 f5 00  82 ed 04 cc  44 83 48 44
			30 b0 30 b0  f7 c4 d5 5c  00 be 29 ff  f0 d0 ff ff
		];
};

<inf> spi_nor: mx25r6435f@1: 64 MiBy flash

But when I want to read and write data in the 16-64m area (i.e. the address exceeds 3 bytes), it cannot correctly recognize the 4-byte address, but instead truncates the lower 24 bits as the address for reading and writing, resulting in the actual read and write address being different from the one I want to read and write,just like this

char test_data[20];
memset(test_data, 0, sizeof(test_data));
strcpy(test_data, "aaabbbccdd987");

flash_write(flash_dev, 0x1800012, test_data, sizeof(test_data));

I found several variables related to 4-byte addresses in spi_nor.c, but did not find where the problem lies

Hieu · Accepted Answer

I have determined that the issue comes from loading the external flash device's capability into the driver. 
 I am honestly not an expert in it, and this is just my rough understanding. I will try to only write about what I am relatively sure of, but I hope you can help me test something to see if it works. 
 The external flash capability is stored in Serial Flash Discoverable Parameters (SFDP). There are two Kconfigs that are relevant to the way the flash driver loads the SFDP: CONFIG_FLASH_JESD216_API and CONFIG_SPI_NOR_SFDP . 
 CONFIG_FLASH_JESD216_API enable some Flash APIs, one of which is flash_sfdp_read (). It loads the SFDP from the external flash device when called. By default, this is disabled. --> Solution 1 : enable CONFIG_FLASH_JESD216_API and call flash_sfdp_read() during initialization. 
 
 As for CONFIG_SPI_NOR_SFDP, by default, it is set to CONFIG_SPI_NOR_SFDP_MINIMAL , synthesize a SFDP based on just the jedec-id and size property of the external flash node on the Devicetree (DT). However, this also defaults the flash address mode to 24-bit, and expects that if 32-bit is needed, then the external flash node has to have the property enter-4byte-addr set properly. I haven't looked into how the value should be derived though... 
 --> Solution 2 : set the enter-4byte-addr property in the external flash node. 
 
 CONFIG_SPI_NOR_SFDP can also be set to CONFIG_SPI_NOR_SFDP_DEVICETREE , which loads the SFDP from the sfdp-bfp of the external flash DT node. This property is already set for the external flash on the nRF9160 DK board file, so it should work. 
 --> Solution 3 : Disable CONFIG_SPI_NOR_SFDP_MINIMAL and enable CONFIG_SPI_NOR_SFDP_DEVICETREE. 
 
 Finally, CONFIG_SPI_NOR_SFDP can also be set to CONFIG_SPI_NOR_SFDP_RUNTIME , which loads SFDP from the external flash device itself during runtime. 
 --> Solution 4 : Disable CONFIG_SPI_NOR_SFDP_MINIMAL and enable CONFIG_SPI_NOR_SFDP_RUNTIME. 
 I realize that I am violating the Occam's Razor principle a lot here, but I figure the information might come in handy eventually for readers with different external flash device, and another reason is that I couldn't test any of them at the moment. 
 Please consider which solution best suit you. 
 Hieu

9160dk external flash operation address length issue

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