Hi, > -----Original Message----- > From: Chris Ball [mailto:cjb@xxxxxxxxxx] > Sent: Tuesday, April 03, 2012 6:12 AM > To: Alan Cooper > Cc: linux-mmc@xxxxxxxxxxxxxxx; Girish K S; Ulf Hansson; Nath, Arindam; > Philip Rakity > Subject: Re: [PATCH] mmc: Prevent 1.8V switch for SD hosts that don't > support UHS modes. > > Hi Al, > > On Mon, Apr 02 2012, Alan Cooper wrote: > > Still hoping for comments on the patch. > > Thanks for the reminder; adding a few potential reviewers to CC:. Acked-by: Arindam Nath <arindam.nath@xxxxxxx> Regards, Arindam > > - Chris. > > > On Fri, Mar 16, 2012 at 3:54 PM, Al Cooper <acooper@xxxxxxxxx> wrote: > >> The driver should not try to switch to 1.8V when the SD 3.0 host > >> controller does not have any UHS capabilities bits set (SDR50, DDR50 > >> or SDR104). See page 72 of "SD Specifications Part A2 SD Host > >> Controller Simplified Specification Version 3.00" under > >> "1.8V Signaling Enable". Instead of setting SDR12 and SDR25 in the > host > >> capabilities data structure for all V3.0 host controllers, only set > them > >> if SDR104, SDR50 or DDR50 is set in the host capabilities register. > This > >> will prevent the switch to 1.8V later. > >> > >> Signed-off-by: Al Cooper <acooper@xxxxxxxxx> > >> --- > >> drivers/mmc/host/sdhci.c | 5 +++-- > >> 1 files changed, 3 insertions(+), 2 deletions(-) > >> > >> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c > >> index 8d66706..cdf900e 100644 > >> --- a/drivers/mmc/host/sdhci.c > >> +++ b/drivers/mmc/host/sdhci.c > >> @@ -2762,8 +2762,9 @@ int sdhci_add_host(struct sdhci_host *host) > >> mmc_card_is_removable(mmc)) > >> mmc->caps |= MMC_CAP_NEEDS_POLL; > >> > >> - /* UHS-I mode(s) supported by the host controller. */ > >> - if (host->version >= SDHCI_SPEC_300) > >> + /* Any UHS-I mode in caps implies SDR12 and SDR25 support. > */ > >> + if (caps[1] & (SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 | > >> + SDHCI_SUPPORT_DDR50)) > >> mmc->caps |= MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25; > >> > >> /* SDR104 supports also implies SDR50 support */ > >> -- > >> 1.7.6 > > -- > Chris Ball <cjb@xxxxxxxxxx> <http://printf.net/> > One Laptop Per Child ��.n��������+%������w��{.n�����{��i��)�� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
