[PATCH V2] mtd: spi-nor: prefer more specific entries from chips database

[Huang Shijie]

On Fri, Nov 07, 2014 at 01:49:36AM +0000, Bean Huo 霍斌斌 (beanhuo) wrote:
> >> 2) n25q128a13 with ID 0x20bb181234
> >> we should prefer entry with the longer ID.
> >I perfer to make a limit before we add new item to the table:
> >   Put the longest one in the first place.
> 
> >By this way, we can avoid the too much "for"s in the following code which makes the code a little complicated.
>  
> >So It should looks like this in the table.     
>  > 1) n25q128a13 with ID 0x20bb181234
>  > 2) n25q128a11 with ID 0x20bb18
> 
> >Hi Brian, what's your opinion?
>   
> >thanks
> >Huang Shijie
> 
> In general,spi nor include three parts Id infor,
> 
> First,it is Manufacturer ID, size is 1 byte.
> 
> Second,it is Device ID,and size is 2 bytes,this sector will include memory
> type and capacity information.
> 
> Third,it is unique ID,and size is 17 bytes(now only used 2 bytes in linux),first byte
> will indicate length of data to follow,second byte is real Extended id,and
> very important.Next 14 bytes is optional,it can be customized factory data. 
> 
> Now in our linux,former two parts all be used for Deivce Id ,ant its size
> is 3 bytes.third part(extended id)be used 2 bytes,and called extended id.
> 
> In our Micron spi nor serials,there are some spi nor that the same Deivce id 
> with different extended ID,so in order to distinguish this,you only add extended id
> infor in struct spi_device_id spi_nor_ids,and don't let relevant spi nor Extended ID field
> is NULL.just as Spansion:
> 
> { "s25sl032p",  INFO(0x010215, 0x4d00,  64 * 1024,  64, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
> { "s25sl064p",  INFO(0x010216, 0x4d00,  64 * 1024, 128, 0) },
> { "s25fl256s0", INFO(0x010219, 0x4d00, 256 * 1024, 128, 0) },
Sometimes, five bytes ID is not enough, please read the patch:
	http://lists.infradead.org/pipermail/linux-mtd/2014-August/055018.html

In current table, Micron's chips do not have five bytes ID yet.
But Spansion has already had many five bytes ID chips now.

thanks
Huang Shijie