From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tudor.Ambarus at microchip.com Date: Tue, 24 Sep 2019 11:36:23 +0000 Subject: [U-Boot] [EXT] [PATCH 2/2] spi-nor: spi-nor-ids: Disable SPI_NOR_4B_OPCODES for n25q512* and n25q256* In-Reply-To: References: <20190910170621.2064-1-vigneshr@ti.com> <20190910170621.2064-2-vigneshr@ti.com> Message-ID: <710074c4-e1f9-972c-3dab-a6a6d6437d45@microchip.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de 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 set >>> >> >> SPI_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. Cheers, ta