On Jun 28, 2011, at 9:42 PM, Jaehoon Chung wrote: > Philip Rakity wrote: >> On Jun 28, 2011, at 3:54 AM, Jaehoon Chung wrote: >> >>> Hi.. >>> >>> I found the MMC_CAP_BUS_WIDTH_TEST... >>> In mailing, I read the related patches.. >>> but i didn't fully understand... >>> >>> /* >>> * If controller can't handle bus width test, >>> * compare ext_csd previously read in 1 bit mode >>> * against ext_csd at new bus width >>> */ >>> if (!(host->caps & MMC_CAP_BUS_WIDTH_TEST)) >>> err = mmc_compare_ext_csds(card, >>> ext_csd, >>> bus_width); >>> else >>> err = mmc_bus_test(card, bus_width); >>> if (!err) >>> break; >>> >>> And i tested suspend/resume..it's failed.. >>> If i didn't set MMC_CAP_BUS_WIDTH_TEST, always return -EINVAL.. >>> (using SDHCI controller, card is eMMC4.41) >>> >>> Didn't compare ext_csd's value.. >>> >>> So i want to know how use MMC_CAP_BUS_WIDTH_TEST.. >> >> I am using eMMC and code works fine so maybe there is issue in no ext_csd. You will need to >> add debug code to the compare_ext_csd and see what is not right and we can adjust the code. >> I am surprised that resume fails -- code will default to 1 bit data and it is NOT possible for this to >> be wrong. At the moment -- clueless to explain with more information. >> >> TheCMD14/ CMD19 is in JEDEC spec for bus width testing. Sends a pattern to the card and >> based on the returned values detects the bus width. Some controllers do NOT support this command. >> The just do not work. You need to figure this out by enabling the quirk. No other way to know. > > When card is probing, i think that need to test bus-width. > If card is non-removable, unnecessary bus_width test during resuming. agree not necessary but does not explain error. > Because already know that support n-bit bus-width..how about this? > >> >> regards, >> >> Philip >> >>> Thanks, >>> Jaehoon Chung >> >> -- >> 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 >> > -- 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
