Hello, > > Stacked: > > Flashes share the same SPI bus, but different CS line, controller > > driver asserts the CS of the flash to which it needs to communicate. > > Stacked mode is a software abstraction rather than a controller feature or > capability. > > At any given time, the controller communicates with one of the two > > connected flash devices, as determined by the requested address and > > data length. If an operation starts on one flash and ends on the > > other, the core needs to split it into two separate operations and > > adjust the data length accordingly. > > > > Parallel(Multi-CS): > > Both the flashes have their separate SPI bus, CS of both the flashes > > will be asserted/de-asserted at the same time. In this mode data will > > be split across both the flashes by enabling the STRIPE setting in the controller. > > Parallel mode is a controller feature where if the STRIPE bit is set > > then the controller internally handles the data split during data > > write to the flashes and while reading data from the flash the > > controller internally merges data from both the flashes before writing to the > controller FIFO. > > If STRIPE is not enabled, then same data will be sent to both the devices. > > In parallel mode both the flashes should be identical. > > Interesting. > > What's the practical use case ? Some kind of RAID directly on raw flashes ? Could it In a parallel configuration, the user can double the flash capacity and data throughput. Users disable STRIPE when they need to access the flash device registers for reading or writing. > help for protecting from a broken boot flash ? No, because each read/write operation communicates with both flash devices simultaneously, meaning the image will be distributed across both flashes and read from both during boot. Regards, Amit > > > --mtx > > -- > --- > Hinweis: unverschlüsselte E-Mails können leicht abgehört und manipuliert werden ! > Für eine vertrauliche Kommunikation senden Sie bitte ihren GPG/PGP-Schlüssel zu. > --- > Enrico Weigelt, metux IT consult > Free software and Linux embedded engineering info@xxxxxxxxx -- +49-151- > 27565287
