On Thursday 12 December 2013, zhangfei wrote: > On 12/12/2013 04:12 AM, Arnd Bergmann wrote: > > On Wednesday 11 December 2013, zhangfei wrote: > > > > But aren't the times fixed for each mode? Why do you need to specify them in > > the DT? I would expect that the clock rates for each mode are set in the > > MMC and SD specifications. When you call clk_set_rate(), it should normally > > be enough to ask for the clock you actually want and let the clk subsystem > > figure out how to set up the parents and multipliers on the way. > > Yes. that's will be perfect. > > However, currently this ip still has no such capability. > Input rate for init are diferent for different controller, not the > init 400K, some are 13M, others are 25M, since different clock source. > This can be easily solved by clock-freq-init = <25000000> > 2. There is maxmum limit, also can be easily solved by define CLK_MAX. > 3. However some mode can not use the max speed from ios->clock > for example UHS_SDR104_MAX_DTR 208000000 can not be used, only half may > be reached, at least currently. I don't fully understand the explanation, but if some of the other people with interest in dw-mmc (I've added some more to Cc now) think this makes sense, I'm fine with it too. > How about this desc > > * clock-freq-table: should be the frequency (in Hz) array of the ciu > clock > in each supported timing. > > 1. CIU clock rate in HZ for MMC_TIMING_LEGACY mode > > 2. CIU clock rate in HZ for MMC_TIMING_MMC_HS mode > 3. CIU clock rate in HZ for MMC_TIMING_SD_HS mode > 4. CIU clock rate in HZ for MMC_TIMING_UHS_SDR12 mode > > 5. CIU clock rate in HZ for MMC_TIMING_UHS_SDR25 mode > > 6. CIU clock rate in HZ for MMC_TIMING_UHS_SDR50 mode > > 7. CIU clock rate in HZ for MMC_TIMING_UHS_SDR104 mode > > 8. CIU clock rate in HZ for MMC_TIMING_SD_HS mode > > 9. CIU clock rate in HZ for MMC_TIMING_MMC_HS200 mode > Yes, that is much better. but please avoid using Linux internal identifiers (e.g. MMC_TIMING_LEGACY) and instead use the terminology from the MMC and SD specs. Also 'Hz' is the official symbol for Hertz, not 'HZ'. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
