On Mon, Aug 03, 2009 at 12:34:29PM +0200, Pierre Ossman wrote: > On Fri, 31 Jul 2009 11:54:07 +0100 > Matt Fleming <matt@xxxxxxxxxxxxxxxxx> wrote: > > > On Fri, Jul 31, 2009 at 12:26:23PM +0200, Pierre Ossman wrote: > > > > > > [PATCH 0/32] mmc and omap_hsmmc patches > > > http://marc.info/?t=124722953900010&r=1&w=2 > > > > > > I haven't looked through these at all. The ones affecting the core > > > probably need some thorough reviews. > > > > > > I did notice the patch to say which cards a controller supports though, > > > and I'm very sceptical about that one. The scanning process should work > > > anyway, and the performance impact should be negligible as it is only > > > on init. So that patch only adds complexity and confusion IMO. > > > > > > > How much complexity does it really add? Surely it's better to give the > > host controller driver writers the ability to not entertain supporting > > some cards if they cannot be used? If they want to avoid the scanning > > process for certain cards, why not let them? > > > > Let's look at the pros and cons of this: > > Con: > > - The scanning code gets less clear as you increase the number of > possible paths through it. > Yes, it does but the function is only small. It's not that much more complexity. And there's a trade off here between the added complexity and the shorter initialisation time for cards. Running initialisation functions on cards that don't need it just seems pointless. > - Different systems will have different init sequences, possibly > provoking bugs in the cards. > Good. I'd like to know about bugs in the cards so that we can fix/work around any issues. This seems like a pretty weak argument against the change to me. > - Host driver writers now have more capability bits they have to > consider. And these might be less than obvious since SD/MMC/SDIO are > normally compatible so these bits seem useless. > Yes, but they also have the flexibility to more clearly describe their host controllers. Besides, any new host controller driver will likely just copy one of the older drivers (which I updated) anyway. > - With the current logic (which was better in the first version), > "normal" drivers will have to explicitly state that they work as > intended by setting all bits. > I thought that the way I wrote the patch was more natural (which was why I rewrote Adrian's to begin with), but if you think the original was clearer I've no issue with pushing that patch through instead. > Pro: > > - A slightly reduced scanning time. > > > I simply don't see it as being worth it. Linux patches generally need > to provide the answer to "Why?", not just be able to avoid "Why not?". > That's not at all what I said, I have provided the why (and so have you by noting the Pro above). -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
