On 02/08/11 09:40, Wolfgang Denk wrote:
Thanks for the speedy response Wolfgang,
Dear Richard Retanubun,
In message4D514F6E.6040101@RuggedCom.com you wrote:
When calling spi_flash_erase, which eventually calls stmicro_erase, one must do so while knowing what the sector_size is of the flash. Is there a recommened API to getting this from struct stmicro_spi_flash_params?
Why would you need to know the sector size?
To align your erase command accordingly?
Yep.
I think you are taking the wrong approach here. Look at how NOR flash is handled: we don't need
to know the sector sizes there either. Instead we support the format "+N" (often used as "+${fileszize}") which will _internally_ round up N to match the next erase block boundary.
Do the same for SPI flash.
If by "how NOR flash in handled" you mean cmd_flash.c::flash_sect_roundb() then yes, I do want to do this but I need to know what number to round it to, no?
In the context of cmd_flash, it has access to flash_info_t which contains the sector_size information. Also cfi_flash.c also provides a function called flash_sector_size() that is called by other components that needs to know. If I have misunderstood what you mean, sorry, please clarify.
To have SPI flash do this, for example; stmicro.c::stmicro_erase() function will auto round up to the nearest sector_size. Which is indeed the simpler way. Right now, most drivers/mtd/spi/*.c just does this check:
<quoted_code> sector_size = stm->params->page_size * stm->params->pages_per_sector;
if (offset % sector_size || len % sector_size) { debug("SF: Erase offset/length not multiple of sector size\n"); return -1; } </quoted_code>
I am worried about unintentionally erasing more than what the caller requested. Would it be better to round up manually and then calls the erase?
Thanks for your time
- Richard