Hi, On Mon, Jun 20, 2016 at 12:29 PM, Guenter Roeck <groeck@xxxxxxxxxx> wrote: > On Mon, Jun 20, 2016 at 10:56 AM, Douglas Anderson > <dianders@xxxxxxxxxxxx> wrote: >> Previous PHY code waited a fixed amount of time for the DLL to lock at >> power on time. Unfortunately, the time for the DLL to lock is actually >> a bit more dynamic and can be longer if the card clock is slower. >> >> Instead of waiting a fixed 30 us, let's now dynamically wait until the >> lock bit gets set. We'll wait up to 10 ms which should be OK even if >> the card clock is at the super slow 100 kHz. >> > > 10 ms active delay (no sleep) is actually quite long. Can this code sleep ? It is expected that in nearly all cases it will be much shorter than 10ms. The longest expected (at 400kHz) is 1.3 ms and we should only be probing down to 300, 200, 100 kHz if we are having trouble communicating. When running at a normal speed (50 MHz, 100 MHz, etc) it should be much smaller and closer to 10 us or less. We could still try to sleep in some of these cases, but IMHO the extra code complexity for something like this that should happen very infrequently (only at bootup or if we decide to re-tune) is probably not worth it. Also note that at boot eMMC is (probably) on the critical path, so there may be some boot speed benefits to continuing as quickly as possible. -Doug -- 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
