On Mon, Oct 17, 2011 at 08:51:11AM -0700, Stephen Warren wrote: > Shawn Guo wrote at Friday, October 14, 2011 9:12 PM: > > On Fri, Oct 14, 2011 at 08:53:33AM -0700, Stephen Warren wrote: > ... > > > Having the driver expose a list of all possible combinations of pin > > > configurations seems impractical, for the same reason as I objected to > > > the original proposal for how the driver listed functions; there are > > > simply far too many pin config parameters and legal value to list the > > > entire set of combinations. > > > > > I did not mean to list the entire set of combinations. For given > > function, the applicable number of config should be very limited. > > For most cases, it could be just one. For imx6q usdhc example, it's > > 3, for 50M, 100M and 200M SD bus clock cases. > > Shawn, > > Are you talking about entries in the (board-specific) mapping table, which > I agree would contain the useful subset of combinations of options, or a > list of possible settings exposed by the SoC driver, which would have to > expose all possibilities, or they wouldn't be available for the mapping > table to select from? > > In the case of "a list of possible settings exposed by the SoC driver", > > * If such a list (of combinations) were to exist, I think it'd need to > include all combinations (the cross-product of all individual config > params) in general. > > * I can certainly imagine that for some SoCs, or for a particular device > on a SoC, or for a particular board, only a subset of those would be useful, > and hence a limited set would be useful. However, that selection is up to > the board mapping table not the SoC driver in general. > > * In Tegra's case at least, I think a number of the numeric values (e.g. > pull strength with range 0..31) may be for board calibration, and besides > that, most combinations of param values would be useful in some case, and > hence we'd always have to expose everything, in order to allow the board > mapping table to be able to pick anything the designer needed. > > * As such, I think the SoC driver should at most list the legal range for > each param individually, and let the board-specific mapping table choose > the combination(s) required. > Yes, I meant the list of settings exposed by pinctrl driver. But it seems that in your case you need to list all the possible combinations of pin configurations. Then I agree it's impractical to have pinctrl driver to maintain this list.
-- Regards, Shawn _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
