Am Montag, 2. Juli 2012, 14:28:37 schrieb Girish K S: > On 2 July 2012 14:23, Girish K S <girish.shivananjappa@xxxxxxxxxx> wrote: > > On 2 July 2012 14:13, Saugata Das <saugata.das@xxxxxxxxxx> wrote: > >> On 2 July 2012 12:26, Venkatraman S <svenkatr@xxxxxx> wrote: > >>> This reverts commit 3d93576e(skip card initialization if > >>> power class selection fails). > >>> Problem has been reported when this is used with eMMC4.41 > >>> card with Tegra Platform. Till the issue is root caused, > >>> bus width selection failure should not be treated as fatal. > >> > >> According to me, we need to find the root issue (which could be either > >> host not able to provide enough current or faulty eMMC). Do we know, > >> what could be the side effect of working on eMMC with less power than > >> what it has requested in PWR_CL ? > >> > >> One known issue with the current power class selection is that we do > >> not check the current requirement for a selected power class. It > >> assumes that host is able to provide the maximum current needed at > >> highest speed (> 800mA). Is it already checked on Tegra ? > > > > and at the least bus width i.e 1 bit mode. > > The MMC card spec has 2 max current values (power class) one for 4 bit > mode and another for 8 bit mode at supported voltages. But the SDHCI > spec has one MaxCur register for supported voltages but doesnt mention > for which bus width. Any input on this is very helpful to resolve the > powerclass issue that is pending the higher nibble is for 8 bit and the lower one for 4 bit. The power class is same for both bus width on this toshiba device. Marc -- 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
