Regression: mx25l12845e stops working on my device after commit 947c86e481a

[Russell Senior]

I am running OpenWrt (master branch) on a Buffalo WZR600DHP. This
particular instance has MX25L12845E SPI NOR chips (I have another
WZR600DHP with Winbond W25Q128BVFG, but haven't tested there, just to
say they don't all necessarily use the same flash).

I just built a new firmware version last night, and it started
unhappily boot looping. The most recent previous build I had done was
from June. Boot looping messages look like this:

[...]
[    0.752843] printk: legacy bootconsole [early0] disabled
[    0.778756] spi-nor spi0.0: supply vcc not found, using dummy regulator
[    0.785909] spi-nor spi0.0: BFPT parsing failed. Please consider
using SPI_NOR_SKIP_SFDP when declaring the flash
[    0.796238] spi-nor spi0.0: probe with driver spi-nor failed with error -22
[    0.804457] spi-nor spi0.1: supply vcc not found, using dummy regulator
[    0.824085] i2c_dev: i2c /dev entries driver
[    0.830852] NET: Registered PF_INET6 protocol family
[    0.872875] Segment Routing with IPv6
[    0.876671] In-situ OAM (IOAM) with IPv6
[    0.880798] NET: Registered PF_PACKET protocol family
[    0.886278] 8021q: 802.1Q VLAN Support v1.8
[    0.921429] clk: Disabling unused clocks
[    0.925661] check access for rdinit=/init failed: -2, ignoring
[    0.932181] MTD: Couldn't look up '': -22
[    0.936335] /dev/root: Can't open blockdev
[    0.940520] VFS: Cannot open root device "" or unknown-block(0,0): error -6
[    0.947472] Please append a correct "root=" boot option; here are
the available partitions:
[    0.955831] 1f00           16384 mtdblock0
[    0.955843]  (driver?)
[    0.962379] List of all bdev filesystems:
[    0.966374]  squashfs
[    0.966379]
[    0.970139] Kernel panic - not syncing: VFS: Unable to mount root
fs on unknown-block(0,0)
[    0.978392] Rebooting in 1 seconds..

Between June and last night, OpenWrt had switched their kernel from a
6.12.x to a 6.18.x, so I immediately suspected something in that
transition was the culprit and demonstrated that by building the last
commit before the change to the 6.18.x kernel, and it worked. Then
tested the commit of the change to the 6.18.x kernel and it
bootlooped.

Then I started looking through the mtd changes between 6.12.x and
6.18.x and spotted 947c86e481a.

  commit 947c86e481a027ed5948434096e506f307bd7114
  Author: Cheng Ming Lin <chengminglin at mxic.com.tw>
  Date:   Mon Apr 7 15:53:58 2025 +0800

      mtd: spi-nor: macronix: Drop the redundant flash info fields

The following revert of just the part that affected my chip made the
bootloop vanish:

diff --git a/drivers/mtd/spi-nor/macronix.c b/drivers/mtd/spi-nor/macronix.c
index e97f5cbd9aad2..3524ed08ff85d 100644
--- a/drivers/mtd/spi-nor/macronix.c
+++ b/drivers/mtd/spi-nor/macronix.c
@@ -132,7 +132,10 @@ static const struct flash_info macronix_nor_parts[] = {
        }, {
                /* MX25L12805D */
                .id = SNOR_ID(0xc2, 0x20, 0x18),
+               .name = "mx25l12805d",
+               .size = SZ_16M,
                .flags = SPI_NOR_HAS_LOCK | SPI_NOR_4BIT_BP,
+               .no_sfdp_flags = SECT_4K,
        }, {
                /* MX25L25635E, MX25L25645G */
                .id = SNOR_ID(0xc2, 0x20, 0x19),
-- 
2.55.0


-- 
Russell Senior
russell at personaltelco.net