On Wednesday 23 July 2008, hartleys wrote: > On Wednesday, July 23, 2008 David Brownell wrote: > >> This patch makes the at25 driver call spi_setup before any read/write > > >> access to the eeprom to insure that the device mode and clock is set > >> correctly. > > > > Why would this be needed though? It was called before probe(), and > > nothing changed the setup ... so it should still be valid. > > With multiple slaves another driver could change the clock.
No it can't. If you're seeing that behavior, it's a bug in your SPI controller driver ... it's not properly keeping track of the device settings. The spi_setup() call only changes records of settings for that device; those settings become active the next time I/O is performed to that device. The controllers often have per-chipselect registers with settings for speed, mode, word size, and so forth. If they don't have such registers, they need to emulate having them. Also, note that your patch wouldn't actually work around that controller driver bug. A driver for a different SPI device could issue requests between the spi_setup() you added and the I/O calls ... - Dave ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ spi-devel-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/spi-devel-general
