From 8ec76705d42766156c4185f59998c7144f815363 Mon Sep 17 00:00:00 2001 From: Christian Marangi Date: Wed, 20 Mar 2024 17:08:30 +0100 Subject: [PATCH] ipq806x: 6.6: add pending patch fixing mtdcore with MTD OTP Add pending patch fixing mtdcore with MTD OTP with a fragile detection if Nand supports OTP. Patch has been sent upstream and will be backported to stable kernel if accepted. Signed-off-by: Christian Marangi --- ...-limit-OTP-nvmem-to-non-nand-devices.patch | 63 +++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 target/linux/ipq40xx/patches-6.6/110-mtd-limit-OTP-nvmem-to-non-nand-devices.patch diff --git a/target/linux/ipq40xx/patches-6.6/110-mtd-limit-OTP-nvmem-to-non-nand-devices.patch b/target/linux/ipq40xx/patches-6.6/110-mtd-limit-OTP-nvmem-to-non-nand-devices.patch new file mode 100644 index 0000000000..80fd20318b --- /dev/null +++ b/target/linux/ipq40xx/patches-6.6/110-mtd-limit-OTP-nvmem-to-non-nand-devices.patch @@ -0,0 +1,63 @@ +From 540dcef6f39d6356d2a65230a8d4e9738ee2d25b Mon Sep 17 00:00:00 2001 +From: Christian Marangi +Date: Wed, 20 Mar 2024 16:43:01 +0100 +Subject: [PATCH] mtd: limit OTP nvmem to non nand devices + +MTD OTP logic is very fragile and can be problematic with some specific +kind of devices. + +NVMEM across the years had various iteration on how Cells could be +declared in DT and MTD OTP probably was left behind and +add_legacy_fixed_of_cells was enabled without thinking of the consequences. + +That option enables NVMEM to scan the provided of_node and treat each +child as a NVMEM Cell, this was to support legacy NVMEM implementation +and don't cause regression. + +This is problematic if we have devices like Nand where the OTP is +triggered by setting a special mode in the flash. In this context real +partitions declared in the Nand node are registered as OTP Cells and +this cause probe fail with -EINVAL error. + +This was never notice due to the fact that till now, no Nand supported +the OTP feature. With commit e87161321a40 ("mtd: rawnand: macronix: OTP +access for MX30LFxG18AC") this changed and coincidentally this Nand is +used on an FritzBox 7530 supported on OpenWrt. + +Alternative and more robust way to declare OTP Cells are already +prossible by using the fixed-layout node or by declaring a child node +with the compatible set to "otp-user" or "otp-factory". + +To fix this and limit any regression with other MTD that makes use of +declaring OTP as direct child of the dev node, disable +add_legacy_fixed_of_cells if we have a node called nand since it's the +standard property name to identify Nand devices attached to a Nand +Controller. + +With the following logic, the OTP NVMEM entry is correctly created with +no Cells and the MTD Nand is correctly probed and partitions are +correctly exposed. + +Fixes: 2cc3b37f5b6d ("nvmem: add explicit config option to read old syntax fixed OF cells") +Cc: +Signed-off-by: Christian Marangi +--- + drivers/mtd/mtdcore.c | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c +index 5887feb347a4..6872477a5129 100644 +--- a/drivers/mtd/mtdcore.c ++++ b/drivers/mtd/mtdcore.c +@@ -900,7 +900,7 @@ static struct nvmem_device *mtd_otp_nvmem_register(struct mtd_info *mtd, + config.name = compatible; + config.id = NVMEM_DEVID_AUTO; + config.owner = THIS_MODULE; +- config.add_legacy_fixed_of_cells = true; ++ config.add_legacy_fixed_of_cells = !of_node_name_eq(mtd->dev.of_node, "nand"); + config.type = NVMEM_TYPE_OTP; + config.root_only = true; + config.ignore_wp = true; +-- +2.43.0 + -- 2.30.2