Issues with SPI NOR flash

[Aaron Williams]

Hi all,

I'm running into a problem with the SPI NOR connected to our host processor. 
We're using a Macronix MX25L25645GMI-08G connected to the spi1 device on an 
AST2500. This device is muxed between our host processor and the BMC. When our 
host processor is powered off, the BMC has exclusive access to it.

Anyway, the behavior is that I can read the SPI NOR without any difficulty, 
however, when I write to it the SPI nor appears to be filled with garbage. If 
I had to guess, I'd guess that the SPI driver is not waiting for the SPI NOR 
to complete the write operation before moving to the next block.

Here is the relevant section from our device tree:

&spi1 {
	status = "okay";
	flash at 0 {
		status = "okay";
		compatible = "jedec,spi-nor", "spi-nor";
		label = "host";
		m25p,fast-read;
		spi-tx-bus-width = <1>;
		spi-rx-bus-width = <1>;
		spi-max-frequency = <50000000>;
		partitions {
			compatible = "fixed-partitions";
			#address-cells = <1>;
			#size-cells = <1>;

			bootloader at 0 {
				reg = <0x0 0x1000000>;
				label = "host-
bootloader";
			};
			kernel at 1000000 {
				reg = <0x1000000 
0x1000000>;
				label = "host-kernel";
			};
		};
	};
};

Note that our host is also running 4.19 and has no trouble writing to the SPI 
NOR. The corruption seems worse when flashcp is used compared to just cp. I 
noticed that flashcp writes in 4K blocks. The Macronix device has a 256 byte 
page buffer. I have tried slowing down the bus to 5MHz and that made no 
difference. Note that we are currently using single bit mode for both the host 
and BMC processors for this flash, though we plan to move to move to QPI on 
the host processor later.

Before the write operation the host processor has not had any access to the 
SPI NOR. The host is powered down and the BMC is rebooted to force a clean 
state.

-Aaron

-- 
Aaron Williams
Senior Software Engineer
Marvell Semiconductor, Inc.
(408) 943-7198	(510) 789-8988 (cell)