Hi Tudor,
On Tue, Sep 24, 2019 at 1:36 PM Tudor.Ambarus@microchip.com wrote:
Hi, Simon,
On 09/23/2019 12:30 PM, Simon Goldschmidt wrote:
cut
> Subject: [EXT] [PATCH 2/2] spi-nor: spi-nor-ids: Disable > SPI_NOR_4B_OPCODES for n25q512* and n25q256* > > Caution: EXT Email > > Not all variants of n25q256* and n25q512* support 4 Byte stateless > addressing opcodes and there is no easy way to discover at runtime whether > the flash supports this feature or not. > Therefore don't set SPI_NOR_4B_OPCODES for these flashes. Hi Vignesh, I think it will be good to keep it here and disable this for boards by using not set flag in config Like # SPI_NOR_4B_OPCODES is not setSPI_NOR_4B_OPCODES is not a config option. Are you suggesting to add one? config options don't scale well especially when same defconfig is used for multiple boards that potentially have different flashes
I'd prefer to take this patch, as this is what Linux does.
No, this is not what Linux does. There is no opt-in or opt-out option. Decision to use 4 byte opcode is done at runtime based on flash that's detected. Either based on info->flags for that part or by parsing SFDP table. There is no config option of DT option to force 4 byte addressing
I think it's better to have an opt-in option. That way, all chips work with the default settings (even if that means some chips don't use 4 baste opcodes even if they could).
One solution would be to look at SFDP tables of two variants of flash and see if there are any differences that can be used as a clue.
Simon, Could you provide dump of SFDP tables and all the 6 bytes READ ID of the flash that you have?
I have a n251256a with JEDEC ID 20, ba, 19, 10, 44, 00.
Is this a n25q256a or a MT25QL256ABA? We want to check if there are n25q256a flashes that have the 6th bit of the Extended Device Id set to one or not. According to n25q256a datasheet the bit 6 is reserved (which probably translates to being zero), while on MT25QL256ABA is set to one.
Right, this really is a MT25QL256ABA, I guess. I'm not quite familiar with the print on the housing, sorry. We had both and here, it's probably the MT, not the nq.
I also wasn't really aware of the differences between those two, sorry.
Regards, Simon
Cheers, ta