CONFIG_SPI_FLASH_W25QXXDV_MAX_DATA_LEN doesn't work in proj.conf

[mazhenke]

In Kconfig.w25qxxdv file:

config SPI_FLASH_W25QXXDV_MAX_DATA_LEN
	int
	range 1 256
	default 256
	help
	  Maximum transmit or receive data length in one user data frame.

I want to change the CONFIG_SPI_FLASH_W25QXXDV_MAX_DATA_LEN value in my project, so I add
CONFIG_SPI_FLASH_W25QXXDV_MAX_DATA_LEN=32 in my proj.conf
but the CONFIG_SPI_FLASH_W25QXXDV_MAX_DATA_LEN in
zephyr/include/generated/autoconf.h
is still 256, and I got the following cmake warning:

warning: SPI_FLASH_W25QXXDV_MAX_DATA_LEN (defined at drivers/flash/Kconfig.w25qxxdv:77) was assigned the value "32" but got the value "256" -- check dependencies

[ulfalizer]

@mazhenke
SPI_FLASH_W25QXXDV_MAX_DATA_LEN doesn't have a prompt, so it can't be set directly from a prj.conf file.

See http://docs.zephyrproject.org/porting/board_porting.html#setting-configuration-values for an overview of how to set symbols with and without prompts.

Currently a Kconfig.defconfig file would be needed to set the value, but only boards and SoCs can have Kconfig.defconfig, afaik. Maybe SPI_FLASH_W25QXXDV_MAX_DATA_LEN is supposed to be a fixed board setting, or there's a problem with how it is defined.

@tbursztyka touched this code recently. He might have some comments.

[tbursztyka]

Perhaps it can be removed (and code modified accordingly).
When I switched that driver to new spi API I got rid of this:
struct spi_flash_data { struct device *spi;
- u8_t buf[CONFIG_SPI_FLASH_W25QXXDV_MAX_DATA_LEN + - W25QXXDV_LEN_CMD_ADDRESS];
`+ struct spi_config spi_cfg;

It looks like this length was only about internal buffer length, which is now useless due to new SPI API.
I'll verify that in the datasheet.

[tbursztyka]

yes it's a left-over. I'll remove that