On 1-1-2011 04:43, Hein_Tibosch wrote: > On 29-12-2010 01:15, Andy Ross wrote: >> I'm working with a eMMC device that broke after this commit: >> >> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=88ae8b86648 >> >> The older hack I'd been given hard-coded the initialisation frequency >> at 200kHz (instead of 400kHz in the original upstream) and works fine. >> >> But the new code tries to dynamically detect the highest frequency >> that will work, but as far as I can tell the logic is wrong. It will >> continue trying after failed mmc_send_*_cond() calls, but *not* after >> failures later on in mmc_attach_{sd,sdio,mmc}. My boards (at 400kHz) >> are getting successful returns from mmc_send_op_cond(), but failing in >> mmc_attach_mmc(). If I retry at 300, it works. >> >> Tested on the same controller using a sdhc card. No idea how the >> extra retries will affect other hardware (though as the original code >> was fixed at 400, presumably very few devices will care?). > > <snip> > > Don't know why all these additions of claim/release? > In some cases it will lead to unnecessary releases, just because > later in the branch claim will be called. > > I think in all 3 cases (sd/sdio/mmc) the change can be much simpler. > For instance for sd.c I would do this: > > --- > diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c > index 49da4df..18331eb > --- a/drivers/mmc/core/sd.c > +++ b/drivers/mmc/core/sd.c > > <snip> > > @@ -825,6 +829,7 @@ int mmc_attach_sd(struct mmc_host *host, u32 ocr) > if (err) > goto remove_card; > > + mmc_claim_host(host); > return 0; > > remove_card: > @@ -833,7 +838,6 @@ remove_card: > mmc_claim_host(host); > err: > mmc_detach_bus(host); > - mmc_release_host(host); > > printk(KERN_ERR "%s: error %d whilst initialising SD card\n", > mmc_hostname(host), err); > -- > I tested the simplified patch as described above on AVR32 with an sd-card. It worked well and the timing was the same as before: each frequency tried takes about 22 ms. The third time, at 200Khz, the card got initialized. But not much time is lost, in a meanwhile it was starting up the USB host Hein -- 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
