On Wed, Jan 27, 2016 at 02:59:14PM +0200, Adrian Hunter wrote: > In my view Ulf needs to explain how the SDHCI library is going to work, > particularly in the absence of new callbacks. We need to add new callbacks as part of the conversion to a library, otherwise we're very much into a total rewrite from scratch (which I think is far too much work, and prone to errors) or a big flag day to switch everything over (which will require a moritorium on sdhci patches while the effort to switch everything is ongoing.) Both of those approaches suffer from one huge drawback: there is no way to bisect between them to locate the cause of a regression. A piece-meal approach, where the driver is gradually converted is a far saner approach, because it means that each conversion in the step can be done as a series of transformations, which not only can be properly reviewed, but also bisected - and that is _hugely_ important for the existing state of SDHCI. The chances of some hardware behavioural quirk being missed while trying to convert SDHCI to a library are _extremely_ high, and the only sane approach to this is one which allows a progressive transformation of the driver. Also, the last thing we want is for drivers to end up duplicating entire functions from sdhci.c just because they have one thing different (eg, because they need to do something in the middle of a set_ios() call which no other SDHCI driver needs.) Having such code duplication will just make maintanence even more of a nightmare. set_ios() is probably one of the worst functions in sdhci right now, and there's no obvious way to split it up into several stand-alone functions which drivers could chain together. I think what needs to happen here is that Ulf needs to leave such decisions about what is acceptable or unacceptable to those who are trying to convert sdhci to a library, otherwise the conversion will probably never happen... unless Ulf wants to get directly involved in the conversion effort, producing patches to make it happen. -- RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
