Re: [PATCH 1/2] dt-bindings: mtd: jedec, spi-nor: Add DT property to avoid setting SRWD bit in status register

Conor Dooley
2023-06-15T19:13:13Z

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On Thu, Jun 15, 2023 at 04:46:48PM +0530, Amit Kumar Mahapatra wrote:
> If the WP signal of the flash device is not connected and the software sets
> the status register write disable (SRWD) bit in the status register then
> thestatus register permanently becomes read-only. To avoid this added a new
> boolean DT property "broken-wp". If WP signal is not connected, then this
> property should be set in the DT to avoid setting the SRWD during status
> register write operation.
>
> Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@amd.com>
> ---
> .../devicetree/bindings/mtd/jedec,spi-nor.yaml | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
> index 89959e5c47ba..a509d34f14b2 100644
> --- a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
> +++ b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
> @@ -70,6 +70,19 @@ properties:
> be used on such systems, to denote the absence of a reliable reset
> mechanism.
>
> + broken-wp:
> + type: boolean
> + description:
> + The SRWD bit in status register, combined with the WP signal provides

Should the first use of SRWD be spelt out as you did in your commit
message?

> + The SRWD bit in status register, combined with the WP signal provides
^
nit: missing a comma here I think.

> + hardware data protection for the device. When the SRWD bit is set to 1,
> + and the WP signal is driven LOW, the status register nonvolatile bits
> + become read-only and the WRITE STATUS REGISTER operation will not execute.
> + The only way to exit this hardware-protected mode is to drive WP HIGH. But
> + if the WP signal of the flash device is not connected then status register
> + permanently becomes read-only as the SRWD bit cannot be reset. This boolean
> + flag can be used on such systems in which WP signal is not connected, to

nit: s/such//

Otherwise, seems reasonable to me & the detail in the description is
nice.
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

Cheers,
Conor.

> + avoid setting the SRWD bit while writing the status register.
> +
> reset-gpios:
> description:
> A GPIO line connected to the RESET (active low) signal of the device.
> --
> 2.17.1
>

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