On Wed, Mar 12, 2014 at 05:46:53PM +0100, Boris BREZILLON wrote: > >>I see at least 3 of those timings that could be useful (for the moment) : > >>- tR: this one should be used to fill the chip_delay field > >>- tPROG and tBERS: could be used within nand_wait to choose the timeo > >> value appropriately. > >IIRC these timing values are really only necessary if the controller > >does not support the READY/BUSY input, in that case drivers typically > >seem to use 'chip_delay' which is the maximum possible command > >execution time (a sleep long enough to guarentee that READY/BUSY is > >de-asserted). > You're right about tR (or chip_delay): it's only used when there are > no R/B pin. I experienced it when I tried the RB_NONE case in the > sunxi driver: the default chip_delay set by the NAND core code was > too small to fit the NAND chip requirements. > > Anyway, I really think the chip_delay field should be set according > to NAND chip characteristics not harcoded in NAND controller driver > code (as currently done). Drivers these days are often taking this value from the DT node property 'chip-delay'. I think this would be nice to have in common code too... > tPROG and tBERS, would be used in nand_wait function and do not > depend on the R/B pin. These are just used as timeouts. tPROG/tBERS have that special mode where R/B remains asserted but you can still issue a status read to the chip to check on the command, so the timeout required here is just a big number to detect failed NAND controllers, it isn't really too important to have an exact value.. > >>Or should I create a new struct for these timings ? > >>In the latter case how should I name it ? > >struct onfi_command_timings ? > > I'm not a big fan of this name. I think timing structs should not > contain onfi in their names, because these timings are also > available on non ONFI chips. Explicitly defering to the ONFI spec makes it clear what the definition of the timing parameter actually is. If JEDEC has a different model then drivers will need to configure their interfaces a little differently. So we might end up with a jedec_sdr_timings too :| > What do you think ? I'd focus on getting the bus timings working before tackling too much more ... Jason -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
