On 4 April 2013 13:44, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote: > On 04/04/13 12:55, Ulf Hansson wrote: >> On 4 April 2013 10:46, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote: >>> On 01/03/13 14:47, Ulf Hansson wrote: >>>> From: Ulf Hansson <ulf.hansson@xxxxxxxxxx> >>>> >>>> The mmc_power_restore|save_host API is only used by SDIO func drivers. SDIO >>> >>> NAK - it is also used by eMMC hardware reset i.e. mmc_do_hw_reset() >> >> True for eMMC, but for SD card the bus_ops can go away. Thanks for >> spotting this Adrian! >> >> Although, I see some serious problems with the mmc_do_hw_reset >> function - it could cause eMMC data corruption. >> >> Issuing hw reset and doing re-initialization by using the mmc >> bus_ops->power_restore will mean no consideration is taken to "cache >> ctrl", "bkops" and "power off notify". I think it must. >> >> So the more proper way instead of calling power_restore, should be to >> use bus_ops->suspend and bus_ops->resume callbacks from the >> mmc_do_hw_reset function. Additionally if bus_ops->suspend is done >> successfully, we should be able to skip the actual hw reset and just >> do bus_ops->resume. >> >> Do you have any thoughts on this? > > Certainly the bootloader should leave the eMMC is a safe state including: > flushing the cache or turning it off (why did it turn on?), stopping > background operations (why did it start them?), disabling power-off > notification CMD0? (again why it it enable it?) Not sure what you mean here. What has a booloader to do with this? > > Note that according to spec. CMD0 anyway clears the cache so you have lost > your data anyway. What I am saying that we can try send "cache ctrl" and "power off notify" before we send CMD0 / do hw reset. The no data shall be lost. > > -- 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
