update: I just tried a quick hack that simply restarts the mmc card probe at f_min if it fails and this allows my 'weirdo' card/host setup to function normally again. I'll knock up a patch implementing this a bit more cleanly and submit it for opinions shortly. 2009/9/29 Ian Molton <ian@xxxxxxxxxxxxxx>: > Ok, I've looked into this and I have a problem. > > First off tmio-mmc was (with reason, albeit possibly bad ones) picking > a 250 kHz clock for init. I've made a patch to fix that, but it doesnt > solve my card-fails-to-init problem. > > I found that this particular card / machine combo just doesnt play > nice initialising at 400kHz (or 250kHz or 512kHz). It wont initialise > at anything over 120kHz in fact. > > The same card works fine in another device with the same (tc6393xb) > host controller. > > BUT the fact is we have a regression - this card used to work, and now > it doesnt. The cause is the patch I identified below that puts a > 400kHz lower limit on the initialisation frequency. > > So, firstly, is there any real advantage to this lower limit? > > Secondly, I now have a problem in that if I want it fixed, it required > machine specific knowledge in the MMC core, which I dont like. > > I propose a more robust solution - if initialisation fails at 400kHz > try again at f_min (if its lower than 400kHz). > > this requires no machine specific knowledge in the core and may > increase robustness generally, as well as fixing my case. > > Comments please? > > 2009/9/29 Ian Molton <ian@xxxxxxxxxxxxxx>: >> Hi folks, >> >> The commit 8dfd0374be84793360db7fff2e635d2cd3bbcb21 is causing one of >> my MMC cards to fail to initialise. >> >> Has anyone else seen initialisation failures since this patch? >> >> I suspect the problem is in tmio-mmc but its a weird one - only one of >> my two tc6393xb based hosts has this issue, and none of t7l66 or >> tc6387, and only with one card. >> >> I'll look into it tomorrow and see what actual clock frequency is >> getting selected. >> >> I'm off to bed now. >> >> -- >> Ian Molton >> Linux, Automotive, and other hacking: >> http://www.mnementh.co.uk/ >> > > > > -- > Ian Molton > Linux, Automotive, and other hacking: > http://www.mnementh.co.uk/ > -- Ian Molton Linux, Automotive, and other hacking: http://www.mnementh.co.uk/ -- 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
