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SubjectRe: [PATCH v3 3/4] nvmem: core: Fix a conflict between MTD and NVMEM on wp-gpios property
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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;

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