Hello Aaron Lu, please check the mmc 4.5 specification CMD21 is tuning command. regards Girish K S On 16 September 2011 10:17, Aaron Lu <aaron.lu@xxxxxxx> wrote: > On Fri, Sep 16, 2011 at 09:41:04AM +0530, Girish K S wrote: >> 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. > > sdhci_execute_tuning will only be called if the inserted card is a sd card > and it is operating at SDR104 or SDR50 mode(UHS-I). > > The host's tuning function is called from the mmc_sd_init_uhs_card, > and for a mmc card, there is no chance of that function being called. > > -Aaron > > -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html