On 08/07/2016 11:07 AM, Shawn Lin wrote: > 在 2016/8/6 22:18, Stefan Wahren 写道: >> Hi Marek, >> >>> Marek Vasut <marex@xxxxxxx> hat am 6. August 2016 um 15:14 geschrieben: >>> >>> >>> On 08/06/2016 02:55 PM, Stefan Wahren wrote: >>>> This patch based on the work of Fabio Estevam: >>>> "[PATCH v2] mmc: core: Do not set mmc voltage to 1.8V when >>>> 'no-1-8-v' is present" >>>> >>>> It adds the support for 3.3V only DDR MMC hosts. >>> >>> Do such cards even exist ? Do you have a link where I can find some ? >> >> i never said anything about SD cards. I mean eMMC modules which usually have 8 >> data pins like this one [1]. >> >> Please don't blame me if it's not compatible to i.MX28. It's only an example. >> >> [1] - >> http://datasheet.octopart.com/THGBM3G4D1FBAIGH2H-Toshiba-datasheet-20748880.pdf > > > I download the datasheet you mentioned, and I explicitly see it > describe 1V8 everywhere, especially for the section of "ELECTRICAL > CHARACTERISTICS". > > I never see one eMMC claiming DDR52 capability but doesn't support 1V8 > so far. Could you kindly share me the part number of the eMMC you are > using? :) > >> >>> >>>> Signed-off-by: Stefan Wahren <stefan.wahren@xxxxxxxx> >>>> --- >>>> drivers/mmc/core/host.c | 2 ++ >>>> drivers/mmc/core/mmc.c | 6 ++++++ >>>> include/linux/mmc/host.h | 1 + >>>> 3 files changed, 9 insertions(+) >>>> >>>> Changes to Fabio's patch: >>>> - rebase to current linux-next >>>> - rename DT property to mmc-ddr-3_3v >>>> - use EXT_CSD_CARD_TYPE_DDR_52 instead of new define >>>> >>>> diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c >>>> index 98f25ff..4c971de 100644 >>>> --- a/drivers/mmc/core/host.c >>>> +++ b/drivers/mmc/core/host.c >>>> @@ -301,6 +301,8 @@ int mmc_of_parse(struct mmc_host *host) >>>> if (of_property_read_bool(np, "wakeup-source") || >>>> of_property_read_bool(np, "enable-sdio-wakeup")) /* legacy */ >>>> host->pm_caps |= MMC_PM_WAKE_SDIO_IRQ; >>>> + if (of_property_read_bool(np, "mmc-ddr-3_3v")) >>>> + host->caps2 |= MMC_CAP2_3_3V_ONLY_DDR; >>>> if (of_property_read_bool(np, "mmc-ddr-1_8v")) >>>> host->caps |= MMC_CAP_1_8V_DDR; >>>> if (of_property_read_bool(np, "mmc-ddr-1_2v")) >>>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c >>>> index f2d185c..8a933d5 100644 >>>> --- a/drivers/mmc/core/mmc.c >>>> +++ b/drivers/mmc/core/mmc.c >>>> @@ -210,6 +210,12 @@ static void mmc_select_card_type(struct mmc_card *card) >>>> avail_type |= EXT_CSD_CARD_TYPE_HS_52; >>>> } >>>> >>>> + if (caps2 & MMC_CAP2_3_3V_ONLY_DDR && >>>> + card_type & EXT_CSD_CARD_TYPE_DDR_1_8V) { >>>> + hs_max_dtr = MMC_HIGH_DDR_MAX_DTR; >>>> + avail_type |= EXT_CSD_CARD_TYPE_DDR_52; >>>> + } did you know EXT_CSD_CARD_TYPE_DDR_52 -> TYPE_DDR_1_8V and TYPE_DDR_1_2V? It means card can use to the 1.8v and 1.2v ddr mode. So this patch is strange..You added capability for only supporting 3_3v. Confusing... Best Regards, Jaehoon Chung >>>> + >>>> if (caps & MMC_CAP_1_8V_DDR && >>>> card_type & EXT_CSD_CARD_TYPE_DDR_1_8V) { >>>> hs_max_dtr = MMC_HIGH_DDR_MAX_DTR; >>>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h >>>> index aa4bfbf..db0775d 100644 >>>> --- a/include/linux/mmc/host.h >>>> +++ b/include/linux/mmc/host.h >>>> @@ -311,6 +311,7 @@ struct mmc_host { >>>> #define MMC_CAP2_HS400_ES (1 << 20) /* Host supports enhanced strobe */ >>>> #define MMC_CAP2_NO_SD (1 << 21) /* Do not send SD commands during >>>> initialization */ >>>> #define MMC_CAP2_NO_MMC (1 << 22) /* Do not send (e)MMC commands during >>>> initialization */ >>>> +#define MMC_CAP2_3_3V_ONLY_DDR (1 << 23) /* Only supports 3.3V DDR */ >>>> >>>> mmc_pm_flag_t pm_caps; /* supported pm features */ >>>> >>>> >>> >>> >>> -- >>> Best regards, >>> Marek Vasut >> -- >> 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 devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html