but there is only one host controller to handle these commands. the generic sdhci driver has cmd19 hard coded, thats the reason I asked the question. you can also check it in the function sdhci_execute_tuning it is hard coded as cmd.opcode = MMC_SEND_TUNING_BLOCK; where the macro value is 19. So in case of SD card insertion it will send a SEND_TUNING_BLOCK command to the device. but if MMC card is inserted then it will send a BUS_TEST_W command to the device. correct me if i am wrong regards Girish On 15 September 2011 21:53, Philip Rakity <prakity@xxxxxxxxxxx> wrote: > > Different committee's --- Different standards. > > There is no issue with overlap. > > > On Sep 15, 2011, at 4:58 AM, Girish K S wrote: > >> Dear all, >> The eMMC 4.5 specification mentions that the CMD21 in >> class 2 is a SEND_TUNING BLOCK command. where as the SD card >> specification >> in the given link says CMD19 in class 2 is the SEND_TUNING_BLOCK >> http://www.scribd.com/doc/50685191/53/Figure-4-8-Send-Tuning-Block-Command. >> Also the implementation in the drivers/mmc/host/sdhci.c uses the CMD19 >> as the SEND_TUNING_BLOCK. >> Can anybody clarify why there is overlapping in this command number. >> May be my understand is wrong. >> >> In the MMC spec the CMD19 is BUS_TEST_W in class 0 and CMD21 is >> reserved till eMMC 4.41 version. >> But in the SD specification (given link) CMD19 is SEND_TUNING_BLOCK >> and CMD21 is reserved. >> >> Thanks and regards >> Girish K S >> -- >> 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
