Hi Rajat,
On 17.10.18 13:52, Rajat Srivastava wrote:
Hi Stefan
Sorry for top-posting.
Why can't we read SFDP parameters from flash and auto-detect 3-byte/4-byte addressing mode? Using address width information we can support both types of flash i.e. flashes supporting 3-byte addressing mode as well as flashes supporting 4-byte addressing mode.
Our flash supports 3- and 4-byte addressing mode. But this special chip is factory strapped to only support 4-byte mode, even though its device ID tells us that it should support also 3-byte mode. This current pretty simple patch enables the use of this flash with very limited code additions. It also helps others (Simon on SoCFPGA) with their issues regarding 3-byte vs 4-byte mode - especially in regard to the bootrom and its setup.
I've floated a similar patch in U-boot that reads and parses SFDP parameters from flash and auto-detects its addressing mode. It send commands according to the address width it detects. Please find the patch set at: https://patchwork.ozlabs.org/cover/985326/ https://patchwork.ozlabs.org/patch/985327/ https://patchwork.ozlabs.org/patch/985329/ https://patchwork.ozlabs.org/patch/985328/
I've just applied your 3 patches and have added SFDP support for our equipped SPI chip (with my patch not applied):
- {"mx25l25635f", INFO(0xc22019, 0x0, 64 * 1024, 512, RD_FULL | WR_QPP) }, + {"mx25l25635f", INFO(0xc22019, 0x0, 64 * 1024, 512, RD_FULL | WR_QPP | SPI_FLASH_USE_SFDP) },
This does not seem to work though:
SF: Detected mx25l25635f with page size 0 Bytes, erase size 64 KiB, total 0 Bytes *** Warning - bad CRC, using default environment
Please note that I'm not opposed to using your SFDP support. But in our case it does not work - at least not without the SPI_FLASH_USE_SFDP addition. And it needs some fixing as well to fully detect the chip parameters. So I would prefer to go ahead with my patch for now.
Thanks, Stefan