Re: [PATCH v3 1/2] mtd: spi-nor: add support to non-uniform SFDP SPI NOR flash memories

Marek Vasut
2018-09-11T18:55:58Z

On 09/11/2018 05:40 PM, Tudor Ambarus wrote:
> Based on Cyrille Pitchen's patch https://lkml.org/lkml/2017/3/22/935.
>
> This patch is a transitional patch in introducing the support of
> SFDP SPI memories with non-uniform erase sizes like Spansion s25fs512s.
> Non-uniform erase maps will be used later when initialized based on the
> SFDP data.
>
> Introduce the memory erase map which splits the memory array into one
> or many erase regions. Each erase region supports up to 4 erase types,
> as defined by the JEDEC JESD216B (SFDP) specification.
>
> To be backward compatible, the erase map of uniform SPI NOR flash memories
> is initialized so it contains only one erase region and this erase region
> supports only one erase command. Hence a single size is used to erase any
> sector/block of the memory.
>
> Besides, since the algorithm used to erase sectors on non-uniform SPI NOR
> flash memories is quite expensive, when possible, the erase map is tuned
> to come back to the uniform case.
>
> The 'erase with the best command, move forward and repeat' approach was
> suggested by Cristian Birsan in a brainstorm session, so:
>
> Suggested-by: Cristian Birsan <cristian.birsan@microchip.com>
> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>

Reviewed-by: Marek Vasut <marek.vasut@gmail.com>

--
Best regards,
Marek Vasut