Hi Vignesh, Tudory, Pratyush, + Tudor and Pratyush christophe.kerello@xxxxxxxxxxx wrote on Mon, 31 Jan 2022 10:57:55 +0100: > Wp-gpios property can be used on NVMEM nodes and the same property can > be also used on MTD NAND nodes. In case of the wp-gpios property is > defined at NAND level node, the GPIO management is done at NAND driver > level. Write protect is disabled when the driver is probed or resumed > and is enabled when the driver is released or suspended. > > When no partitions are defined in the NAND DT node, then the NAND DT node > will be passed to NVMEM framework. If wp-gpios property is defined in > this node, the GPIO resource is taken twice and the NAND controller > driver fails to probe. > > A new Boolean flag named skip_wp_gpio has been added in nvmem_config. > In case skip_wp_gpio is set, it means that the GPIO is handled by the > provider. Lets set this flag in MTD layer to avoid the conflict on > wp_gpios property. > > Signed-off-by: Christophe Kerello <christophe.kerello@xxxxxxxxxxx> > --- > drivers/mtd/mtdcore.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c > index 70f492dce158..e6d251594def 100644 > --- a/drivers/mtd/mtdcore.c > +++ b/drivers/mtd/mtdcore.c > @@ -546,6 +546,7 @@ static int mtd_nvmem_add(struct mtd_info *mtd) > config.stride = 1; > config.read_only = true; > config.root_only = true; > + config.skip_wp_gpio = true; > config.no_of_node = !of_device_is_compatible(node, "nvmem-cells"); > config.priv = mtd; > > @@ -833,6 +834,7 @@ static struct nvmem_device *mtd_otp_nvmem_register(struct mtd_info *mtd, > config.owner = THIS_MODULE; > config.type = NVMEM_TYPE_OTP; > config.root_only = true; > + config.skip_wp_gpio = true; > config.reg_read = reg_read; > config.size = size; > config.of_node = np; TLDR: There is a conflict between MTD and NVMEM, who should handle the WP pin when there is one? At least for raw NAND devices, I don't want the NVMEM core to handle the wp pin. So we've introduced this skip_wp_gpio nvmem config option. But there are two places where this boolean can be set and one of these is for otp regions (see above). In this case, I don't know if it is safe or if CFI/SPI-NOR rely on the nvmem protection. Please tell us if you think this is fine for you. Thanks, Miquèl
