Hi Girish, > -----Original Message----- > From: linux-mmc-owner@xxxxxxxxxxxxxxx [mailto:linux-mmc- > owner@xxxxxxxxxxxxxxx] On Behalf Of Girish K S > Sent: Friday, September 23, 2011 8:42 PM > To: linux-mmc@xxxxxxxxxxxxxxx > Cc: cjb@xxxxxxxxxx; kgene.kim@xxxxxxxxxxx; patches@xxxxxxxxxx; linux- > samsung-soc@xxxxxxxxxxxxxxx; Girish K S > Subject: [PATCH V5] mmc: core: eMMC 4.5 Power Class Selection Feature > > This patch adds the power class selection feature available > for mmc versions 4.0 and above. > During the enumeration stage before switching to the lower > data bus, check if the power class is supported for the > current bus width. If the power class is available then > switch to the power class and use the higher data bus. If > power class is not supported then switch to the lower data > bus in a worst case. > > Signed-off-by: Girish K S <girish.shivananjappa@xxxxxxxxxx> > --- > Changes in v1: > This version modifies the power_class_select function > prototype. > During device enumeration, when the host tries to read the > extended > csd register after switching to higher bus width, the read > fails at > higher bus width. So the power_class_select function is > modified to > reuse the extended csd register values read with 1 bit bus > width. > > Changes in v2: > This patch version removes some checkpatch error > > Changes in v3: > updated with review comments made by chris ball. patch > generated > by rebasing to chris balls mmc-next branch. > > Changes in v4: > updated with review comments. > > Changes in v5: > Replace break statement with appropriate return error value in > drivers/mmc/core/mmc.c for unsupported voltage range. > > drivers/mmc/core/mmc.c | 96 > +++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/mmc/mmc.h | 14 +++++++ > 2 files changed, 110 insertions(+), 0 deletions(-) > > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c > index 7adc30d..c2334d6 100644 > --- a/drivers/mmc/core/mmc.c > +++ b/drivers/mmc/core/mmc.c > @@ -532,6 +532,86 @@ static struct device_type mmc_type = { > }; > > /* > + * Select the PowerClass for the current bus width > + * If power class is defined for 4/8 bit bus in the > + * extended CSD register, select it by executing the > + * mmc_switch command. > + */ > +static int mmc_select_powerclass(struct mmc_card *card, > + unsigned int bus_width, u8 *ext_csd) > +{ > + int err = 0; > + unsigned int pwrclass_val; > + unsigned int index = 0; > + struct mmc_host *host; > + > + BUG_ON(!card); > + > + host = card->host; > + BUG_ON(!host); > + > + if (ext_csd == NULL) > + return 0; > + > + /* Power class selection is supported for versions >= 4.0 */ > + if (card->csd.mmca_vsn < CSD_SPEC_VER_4) > + return 0; > + > + /* Power class values are defined only for 4/8 bit bus */ > + if (bus_width == EXT_CSD_BUS_WIDTH_1) > + return 0; > + > + switch (1 << host->ios.vdd) { > + case MMC_VDD_165_195: > + if (host->ios.clock <= 26000000) > + index = EXT_CSD_PWR_CL_26_195; > + else if (host->ios.clock <= 52000000) > + index = (bus_width <= EXT_CSD_BUS_WIDTH_8) ? > + EXT_CSD_PWR_CL_52_195 : > + EXT_CSD_PWR_CL_DDR_52_195; > + else if (host->ios.clock <= 200000000) > + index = EXT_CSD_PWR_CL_200_195; > + break; > + case MMC_VDD_32_33: > + case MMC_VDD_33_34: > + case MMC_VDD_34_35: > + case MMC_VDD_35_36: > + if (host->ios.clock <= 26000000) > + index = EXT_CSD_PWR_CL_26_360; > + else if (host->ios.clock <= 52000000) > + index = (bus_width <= EXT_CSD_BUS_WIDTH_8) ? > + EXT_CSD_PWR_CL_52_360 : > + EXT_CSD_PWR_CL_DDR_52_360; > + else if (host->ios.clock <= 200000000) > + index = EXT_CSD_PWR_CL_200_360; > + break; > + default: > + pr_warning("%s: Voltage range not supported " > + "for power class.\n", mmc_hostname(host)); > + return -EINVAL; > + } > + > + pwrclass_val = ext_csd[index]; > + > + if (bus_width & (EXT_CSD_BUS_WIDTH_8 | EXT_CSD_DDR_BUS_WIDTH_8)) > + pwrclass_val = (pwrclass_val & EXT_CSD_PWR_CL_8BIT_MASK) >> > + EXT_CSD_PWR_CL_8BIT_SHIFT; > + else > + pwrclass_val = (pwrclass_val & EXT_CSD_PWR_CL_4BIT_MASK) >> > + EXT_CSD_PWR_CL_4BIT_SHIFT; > + > + /* If the power class is different from the default value */ > + if (pwrclass_val > 0) { > + err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, > + EXT_CSD_POWER_CLASS, > + pwrclass_val, > + 0); > + } Sorry for late review. But I see an issue here. You are reading the max. power class supported by card for particular voltage and frequency. And setting that max. power class in POWER_CLASS field without checking if host power supply (regulators which are powering VCC and VCCQ lines of eMMC) is capable of supplying this much current or not? Not all host regulators connected to eMMC might be able to support max. current specified by card (via power class field). SD3.01 specification also has concept of max. current based on bus speed mode. That's why we have following host capability under "include/linux/mmc/host.h" file: #define MMC_CAP_MAX_CURRENT_200 (1 << 26) /* Host max current limit is 200mA */ #define MMC_CAP_MAX_CURRENT_400 (1 << 27) /* Host max current limit is 400mA */ #define MMC_CAP_MAX_CURRENT_600 (1 << 28) /* Host max current limit is 600mA */ #define MMC_CAP_MAX_CURRENT_800 (1 << 29) /* Host max current limit is 800mA */ So basically we should allow host to specify how much current it is capable of sourcing and then set the min of (max. current specified card power class, max. current host is capable of sourcing) as POWER_CLASS rather than blindly setting what card requires. > + > + return err; > +} > + > +/* > * Handle the detection and initialisation of a card. > * > * In the case of a resume, "oldcard" will contain the card > @@ -787,6 +867,14 @@ static int mmc_init_card(struct mmc_host *host, > u32 ocr, > bus_width = bus_widths[idx]; > if (bus_width == MMC_BUS_WIDTH_1) > ddr = 0; /* no DDR for 1-bit width */ > + err = mmc_select_powerclass(card, > ext_csd_bits[idx][0], > + ext_csd); > + if (err) > + pr_err("%s: power class selection to " > + "bus width %d failed\n", > + mmc_hostname(card->host), > + 1 << bus_width); > + > err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, > EXT_CSD_BUS_WIDTH, > ext_csd_bits[idx][0], > @@ -810,6 +898,14 @@ static int mmc_init_card(struct mmc_host *host, > u32 ocr, > } > > if (!err && ddr) { > + err = mmc_select_powerclass(card, > ext_csd_bits[idx][1], > + ext_csd); > + if (err) > + pr_err("%s: power class selection to " > + "bus width %d ddr %d failed\n", > + mmc_hostname(card->host), > + 1 << bus_width, ddr); > + > err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, > EXT_CSD_BUS_WIDTH, > ext_csd_bits[idx][1], > diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h > index ed8fca8..50af227 100644 > --- a/include/linux/mmc/mmc.h > +++ b/include/linux/mmc/mmc.h > @@ -279,10 +279,15 @@ struct _mmc_csd { > #define EXT_CSD_ERASED_MEM_CONT 181 /* RO */ > #define EXT_CSD_BUS_WIDTH 183 /* R/W */ > #define EXT_CSD_HS_TIMING 185 /* R/W */ > +#define EXT_CSD_POWER_CLASS 187 /* R/W */ > #define EXT_CSD_REV 192 /* RO */ > #define EXT_CSD_STRUCTURE 194 /* RO */ > #define EXT_CSD_CARD_TYPE 196 /* RO */ > #define EXT_CSD_PART_SWITCH_TIME 199 /* RO */ > +#define EXT_CSD_PWR_CL_52_195 200 /* RO */ > +#define EXT_CSD_PWR_CL_26_195 201 /* RO */ > +#define EXT_CSD_PWR_CL_52_360 202 /* RO */ > +#define EXT_CSD_PWR_CL_26_360 203 /* RO */ > #define EXT_CSD_SEC_CNT 212 /* RO, 4 bytes */ > #define EXT_CSD_S_A_TIMEOUT 217 /* RO */ > #define EXT_CSD_REL_WR_SEC_C 222 /* RO */ > @@ -294,6 +299,11 @@ struct _mmc_csd { > #define EXT_CSD_SEC_ERASE_MULT 230 /* RO */ > #define EXT_CSD_SEC_FEATURE_SUPPORT 231 /* RO */ > #define EXT_CSD_TRIM_MULT 232 /* RO */ > +#define EXT_CSD_PWR_CL_200_195 236 /* RO */ > +#define EXT_CSD_PWR_CL_200_360 237 /* RO */ > +#define EXT_CSD_PWR_CL_DDR_52_195 238 /* RO */ > +#define EXT_CSD_PWR_CL_DDR_52_360 239 /* RO */ > +#define EXT_CSD_POWER_OFF_LONG_TIME 247 /* RO */ > > /* > * EXT_CSD field definitions > @@ -332,6 +342,10 @@ struct _mmc_csd { > #define EXT_CSD_RST_N_EN_MASK 0x3 > #define EXT_CSD_RST_N_ENABLED 1 /* RST_n is enabled on card > */ > > +#define EXT_CSD_PWR_CL_8BIT_MASK 0xF0 /* 8 bit PWR CLS */ > +#define EXT_CSD_PWR_CL_4BIT_MASK 0x0F /* 8 bit PWR CLS */ > +#define EXT_CSD_PWR_CL_8BIT_SHIFT 4 > +#define EXT_CSD_PWR_CL_4BIT_SHIFT 0 > /* > * MMC_SWITCH access modes > */ > -- > 1.7.1 > > -- > 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 linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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