Hi Subhash, > -----Original Message----- > From: subhashj@xxxxxxxxxxxxxx [mailto:subhashj@xxxxxxxxxxxxxx] > Sent: Thursday, March 03, 2011 6:46 PM > To: Nath, Arindam; cjb@xxxxxxxxxx > Cc: linux-mmc@xxxxxxxxxxxxxxx; Su, Henry; Lu, Aaron; > anath.amd@xxxxxxxxx > Subject: RE: [PATCH 02/12] mmc: sd: add support for signal voltage > switch procedure > > > > > -----Original Message----- > > From: linux-mmc-owner@xxxxxxxxxxxxxxx [mailto:linux-mmc- > > owner@xxxxxxxxxxxxxxx] On Behalf Of Nath, Arindam > > Sent: Wednesday, March 02, 2011 1:36 PM > > To: subhashj@xxxxxxxxxxxxxx; cjb@xxxxxxxxxx > > Cc: linux-mmc@xxxxxxxxxxxxxxx; Su, Henry; Lu, Aaron; > > anath.amd@xxxxxxxxx > > Subject: RE: [PATCH 02/12] mmc: sd: add support for signal voltage > > switch procedure > > > > Hi Subhash, > > > > > > > -----Original Message----- > > > From: subhashj@xxxxxxxxxxxxxx [mailto:subhashj@xxxxxxxxxxxxxx] > > > Sent: Tuesday, March 01, 2011 9:33 PM > > > To: Nath, Arindam; cjb@xxxxxxxxxx > > > Cc: linux-mmc@xxxxxxxxxxxxxxx; Su, Henry; Lu, Aaron; > > > anath.amd@xxxxxxxxx > > > Subject: RE: [PATCH 02/12] mmc: sd: add support for signal voltage > > > switch procedure > > > > > > > > > > > > > -----Original Message----- > > > > From: linux-mmc-owner@xxxxxxxxxxxxxxx [mailto:linux-mmc- > > > > owner@xxxxxxxxxxxxxxx] On Behalf Of Arindam Nath > > > > Sent: Tuesday, February 15, 2011 3:05 PM > > > > To: cjb@xxxxxxxxxx > > > > Cc: linux-mmc@xxxxxxxxxxxxxxx; henry.su@xxxxxxx; > aaron.lu@xxxxxxx; > > > > anath.amd@xxxxxxxxx; Arindam Nath > > > > Subject: [PATCH 02/12] mmc: sd: add support for signal voltage > > switch > > > > procedure > > > > > > > > Host Controller v3.00 adds another Capabilities register. We can > > > > directly read this register without any version checking since > the > > > > new register bits will be considred as reserved in older > > controllers, > > > > and will be read as 0. Apart from other things, this new register > > > > indicates whether the Host Controller supports SDR50, SDR104, and > > > > DDR50 UHS-I modes. So depending on the host support, we set > > > > the corresponding MMC_CAP_* flags. One more new register. Host > > > Control2 > > > > is added in v3.00, which is used during Signal Voltage Switch > > > prcedure > > > > described below. > > > > > > > > Since as per v3.00 spec, UHS-I supported hosts should set S18R to > > 1, > > > > we set S18R (bit 24) of OCR before sending ACMD41. We also need > to > > > set > > > > XPC (bit 28) of OCR in case the host can supply >150mA. This > > support > > > is > > > > indicated by the Maximum Current Capabilities register of the > Host > > > > Controller. > > > > > > > > If the response of ACMD41 has both CCS and S18A set, we start the > > > > signal voltage switch procedure, which if successfull, will > switch > > > > the card from 3.3V signalling to 1.8V signalling. Signal voltage > > > > switch procedure adds support for a new command CMD11 in the > > Physical > > > > Layer Spec v3.01. As part of this procedure, we need to set 1.8V > > > > Signalling > > > > Enable (bit 3) of Host Control2 register, which if remains set > > after > > > > 5ms, > > > > means the switch to 1.8V signalling is successfull. Otherwise, we > > > clear > > > > bit 24 of OCR and retry the initialization sequence. > > > > > > > > Signed-off-by: Arindam Nath <arindam.nath@xxxxxxx> > > > > --- > > > > drivers/mmc/core/sd.c | 37 ++++++++++- > > > > drivers/mmc/core/sd_ops.c | 25 ++++++++ > > > > drivers/mmc/core/sd_ops.h | 1 + > > > > drivers/mmc/host/sdhci.c | 147 > > > > +++++++++++++++++++++++++++++++++++++++++---- > > > > drivers/mmc/host/sdhci.h | 18 +++++- > > > > include/linux/mmc/host.h | 8 +++ > > > > include/linux/mmc/sd.h | 1 + > > > > 7 files changed, 219 insertions(+), 18 deletions(-) > > > > > > > > diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c > > > > index b3f8a3c..e968d5c 100644 > > > > --- a/drivers/mmc/core/sd.c > > > > +++ b/drivers/mmc/core/sd.c > > > > @@ -408,6 +408,7 @@ struct device_type sd_type = { > > > > int mmc_sd_get_cid(struct mmc_host *host, u32 ocr, u32 *cid) > > > > { > > > > int err; > > > > + u32 rocr; > > > > > > > > /* > > > > * Since we're changing the OCR value, we seem to > > > > @@ -427,10 +428,25 @@ int mmc_sd_get_cid(struct mmc_host *host, > u32 > > > > ocr, u32 *cid) > > > > if (!err) > > > > ocr |= 1 << 30; > > > > > > > > - err = mmc_send_app_op_cond(host, ocr, NULL); > > > > + /* If the host can supply more than 150mA, XPC should be set > to > > > > 1. */ > > > > + if (host->caps & (MMC_CAP_SET_XPC_330 | MMC_CAP_SET_XPC_300 | > > > > + MMC_CAP_SET_XPC_180)) > > > > + ocr |= 1 << 28; > > > > + > > > > > > Why do you need MMC_CAP_SET_XPC_300 here? MMC_CAP_SET_XPC_330 & > > > MMC_CAP_SET_XPC_180 is not enough? > > > > According to the Host Controller Spec v3.00, section 2.2.26: > > > > "If a Host System can afford more than 150mA, Host Driver set XPC to > > 1." > > > > Now since >150mA can be set for 1.8V, 3.0V and 3.3V, the above > > condition checks for all these cases. > > > > 3.0v and 3.3v is part of High voltage range supported by card (2.7v- > 3.3v). > Now if host supports any voltage from this range with 150ma driver > strength > then I think only config say MMC_CAP_SET_XPC_HV (high voltage) should > be set > by > host and then only one check required here. Does it make sense? You have a valid point here. But I kept the configs *XPC_300 and *XPC_330 separate so that in future if someone wants to base his/her code on either of the flags being set, but not both, they can easily do so. If you still think it is a good idea to have a common *CAP for both of them, please let me know. I will modify the code accordingly. Thanks, Arindam -- 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
