linux-kernel - Re: [PATCH v3 0/2] add support to non-uniform SFDP SPI NOR flash memories

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Date:   Tue, 18 Sep 2018 15:09:34 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Tudor Ambarus <tudor.ambarus@...rochip.com>
Cc:     <marek.vasut@...il.com>, <dwmw2@...radead.org>,
        <computersforpeace@...il.com>, <richard@....at>,
        linux-kernel@...r.kernel.org, nicolas.ferre@...rochip.com,
        cyrille.pitchen@...rochip.com, linux-mtd@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, Cristian.Birsan@...rochip.com
Subject: Re: [PATCH v3 0/2] add support to non-uniform SFDP SPI NOR flash
 memories

On Tue, 11 Sep 2018 18:40:05 +0300
Tudor Ambarus <tudor.ambarus@...rochip.com> wrote:

> Backward compatibility test done on mx25l3273fm2i-08g with
> CONFIG_MTD_SPI_NOR_USE_4K_SECTORS set and unset.
> Non-uniform erase test done on sst26vf064b-104i/sn with
> CONFIG_MTD_SPI_NOR_USE_4K_SECTORS set and unset.
> 
> Note that in order to do the non-uniform test you'll have to force the
> spi_nor_has_uniform_erase() to return false, because the erase map is
> tuned to come back to the uniform case. Also, for the SST flashes, you'll
> have to unlock the global protection (see
> https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1763887.html).
> 
> Changes in v3:
> - drop "mtd: spi-nor: parse SFDP 4-byte Address Instruction Table":
>   let's add just a feature per patch set to make it easily digestible.
>   No worries, will resubmit it once the non-uniform erase supports gets
>   approved.
> - SNOR_ERASE_FLAGS_OFFSET was buggy and since it's used only once
>   in the uniform erase case, remove it entirely and do the init by
>   hand
> - describe all introduced functions together with arguments and
>   return value
> - various minor updates: drop a cast, rename a function - cosmetics ...
> 
> Changes in v2:
> - add JESD216B SFDP optional parsers: Sector Map Parameter Table parser and
>   4-byte Address Instruction Table parser (patch 2/3 and patch 3/3).
> 
> - save the Erase Types from bfpt to determine the Erase Type sizes. Sort all
>   the map's Erase Types in ascending order with the smallest erase size being
>   the first member in the erase_type array. Sort in the same way the Erase Type
>   mask in regions in order to have a 1-to-1 correspondence with the Erase
>   Types defined in the map. We sort the Erase Type by size, at init, in order to
>   speed up the process of finding the best erase command at run-time.
> 
> - remove setting of mtd->erasesize and nor->erase_opcode when parsing the Basic
>   Flash Parameter Table. mtd->erasesize was set to the maximum supported Erase
>   Type size, without verifying if that Erase Type can erase the entire flash.
>   mtd->erasesize is now set just in spi_nor_select_erase(), after we find which
>   Erase Types are supported in the uniform case.
> 
> - spi_nor_select_erase(): pass directly info->sector_size instead of the whole
>   flash_info structure in order to simplify the code.
> 
> - fix condition on finding erase regions:
>   while (addr < region_start || addr >= region_end) {
> - fix the list command adding: list_add_tail() instead of list_add()
> - write_enable(nor); before erasing the sectors
> - As Boris suggested, remove likely() because it doesn't make any difference
>   given the time it takes to actually erase the block.
> - bool return value for spi_nor_has_uniform_erase().
> 
> Changes in v1 or what I've done on top of Cyrille's work (https://lkml.org/lkml//
> 2017/4/15/70):
> - minimize the amount of erase() calls by using the best sequence of erase
>   type commands depending on alignment.
> - build the list of best fitted erase commands to be executed once we
>   validate that the erase can be performed.
> - add improvements on how the erase map is handled. The regions are
>   consecutive in the address space, walk through the regions incrementally.
> - speed up finding the best erase type command. Order erase types by
>   size, iterate them from the biggest to the smallest and stop when best
>   fitted command is found.
> - determine at init if there are erase types that can erase the entire
>   memory
> - fix support for overlaid regions.
> 
> 
> Tudor Ambarus (2):
>   mtd: spi-nor: add support to non-uniform SFDP SPI NOR flash memories
>   mtd: spi-nor: parse SFDP Sector Map Parameter Table

Queued to spi-nor/next after fixing the kerneldoc headers.

Thanks,

Boris