Re: [PATCH 1/1] arm: Fix unavailable MTD userland devices on Excito B3 boards

On Sat, Feb 07, 2015 at 04:04:59PM +0100, Gordon Bos wrote:

Hi,

I've had some further discussion on this with another B3 owner.
According to an old patch that Excito corporation built for kernel
version 2.6 the flash memory is in fact a ||Numonyx MP25P16
The driver however must be m25p80.

Hi Gordon

Here is what my B3 says during boot:

m25p80 spi0.0: m25p16 (2048 Kbytes)
3 ofpart partitions found on MTD device spi0.0
Creating 3 MTD partitions on "spi0.0":
0x000000000000-0x0000000c0000 : "u-boot"
0x0000000c0000-0x0000000e0000 : "u-boot env"
0x0000000e0000-0x000000200000 : "data"

m25p80 is the driver being used. The device is an m25p16.

 			m25p16@0 {
 				#address-cells = <1>;
 				#size-cells = <1>;
-				compatible = "st,m25p16";
+				compatible = "st,m25p80";

Here, compatibility indicates what the device is. The kernel will then
find a driver for that device. If you look in
drivers/mtd/devices/m25p80.c you see a long list of devices this
driver supports, of which m25p16.

Also, if you specify the wrong device here, the kernel will complain
when it asks the device to identify itself and find it is different:

http://lxr.free-electrons.com/source/drivers/mtd/spi-nor/spi-nor.c#L915

it will print a message: "found %s, expected %s\n"

Are you seeing such a message? Maybe your B3 has a different device
than mine?

Thanks
	Andrew
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