On 17/02/2022 14:47, Christophe Kerello wrote:

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.

It would be possible to set config->wp_gpio at MTD level before calling nvmem_register function but NVMEM framework will toggle this GPIO on each write when this GPIO should only be controlled at NAND level driver to ensure that the Write Protect has not been enabled.

A way to fix this conflict is to add a new boolean flag in nvmem_config named ignore_wp. In case ignore_wp is set, the GPIO resource will be managed by the provider.

Fixes: 2a127da461a9 ("nvmem: add support for the write-protect pin") Signed-off-by: Christophe Kerello christophe.kerello@foss.st.com Cc: stable@vger.kernel.org

---

Changes in v3:

• add a fixes tag.
• rename skip_wp_gpio by ignore_wp in nvmen_config.

Applied thanks,

--srini

Changes in v2:

• rework the proposal done to fix a conflict between MTD and NVMEM on wp-gpios property.

drivers/nvmem/core.c | 2 +- include/linux/nvmem-provider.h | 4 +++- 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index 23a38dcf0fc4..9fd1602b539d 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -771,7 +771,7 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) if (config->wp_gpio) nvmem->wp_gpio = config->wp_gpio;

• else

• else if (!config->ignore_wp) nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp", GPIOD_OUT_HIGH); if (IS_ERR(nvmem->wp_gpio)) {

diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h index 98efb7b5660d..c9a3ac9efeaa 100644 --- a/include/linux/nvmem-provider.h +++ b/include/linux/nvmem-provider.h @@ -70,7 +70,8 @@ struct nvmem_keepout {

• @word_size: Minimum read/write access granularity.
• @stride: Minimum read/write access stride.
• @priv: User context passed to read/write callbacks.

• • @wp-gpio: Write protect pin

• • @wp-gpio: Write protect pin
• • @ignore_wp: Write Protect pin is managed by the provider.
  • Note: A default "nvmem<id>" name will be assigned to the device if
  • no name is specified in its configuration. In such case "<id>" is

@@ -92,6 +93,7 @@ struct nvmem_config { enum nvmem_type type; bool read_only; bool root_only;

• bool ignore_wp; struct device_node *of_node; bool no_of_node; nvmem_reg_read_t reg_read;