MMC: Fix handling of low-voltage cards
PATCH 1/1 MMC: Fix handling of low-voltage cards
Fix handling of low voltage MMC cards.
The latest MMC and SD specs both agree that support for low-voltage operations is indicated by bit 7 in the OCR. The MMC spec states that the low voltage range is 1.65-1.95V while the SD spec leaves the actual voltage range undefined - meaning that there is still no such thing as a low voltage SD card.
However, an old Sandisk spec implied that bits 7.0 represented voltages below 2.0V in 1V or 0.5V increments, and the code was accordingly written with that expectation.
This confusion meant that host drivers attempting to support the typical low voltage (1.8V) would set the wrong bits in the host OCR mask (usually bits 5 and/or 6) resulting in the the low voltage mode never being used.
This change corrects the low voltage range and adds sanity checks on the reserved bits (0-6) and for SD cards that claim to support low-voltage operations.
drivers/mmc/core/core.c +18 -0
@@ -317,6 +317,24 @@ static u32 mmc_select_voltage(struct mmc {int bit; +/* +* Sanity check the voltages that the card claims to +* support. +*/ +if (ocr &0x7F ) { +printk ("%s: card claims to support voltages below " +"the defined range. These will be ignored.\n" , +mmc_hostname (host)); + ocr &= ~0x7F ; + } + +if (host->mode ==MMC_MODE_SD && (ocr &MMC_VDD_165_195 )) { +printk ("%s: SD card claims to support the incompletely " +"defined 'low voltage range'. This will be ignored.\n" , +mmc_hostname (host)); + ocr &= ~MMC_VDD_165_195 ; + } + ocr &= host->ocr_avail; bit =ffs (ocr);
drivers/mmc/host/sdhci.c +2 -3
@@ -669,8 +669,7 @@ static void sdhci_set_power(struct sdhci pwr =SDHCI_POWER_ON ;switch (1 << power) { -case MMC_VDD_17_18 : -case MMC_VDD_18_19 : +case MMC_VDD_165_195 : pwr |=SDHCI_POWER_180 ;break ;case MMC_VDD_29_30 :
@@ -1290,7 +1289,7 @@ static int __devinit sdhci_probe_slot(stif (caps &SDHCI_CAN_VDD_300 ) mmc->ocr_avail |=MMC_VDD_29_30 |MMC_VDD_30_31 ;if (caps &SDHCI_CAN_VDD_180 ) - mmc->ocr_avail |=MMC_VDD_17_18 |MMC_VDD_18_19 ; + mmc->ocr_avail |=MMC_VDD_165_195 ;if (mmc->ocr_avail ==0 ) { printk(KERN_ERR "%s: Hardware doesn't report any "
include/linux/mmc/host.h +1 -8
@@ -65,14 +65,7 @@ struct mmc_host {unsigned int f_max;u32 ocr_avail; -#define MMC_VDD_145_150 0x00000001/* VDD voltage 1.45 - 1.50 */ -#define MMC_VDD_150_155 0x00000002/* VDD voltage 1.50 - 1.55 */ -#define MMC_VDD_155_160 0x00000004/* VDD voltage 1.55 - 1.60 */ -#define MMC_VDD_160_165 0x00000008/* VDD voltage 1.60 - 1.65 */ -#define MMC_VDD_165_170 0x00000010/* VDD voltage 1.65 - 1.70 */ -#define MMC_VDD_17_18 0x00000020/* VDD voltage 1.7 - 1.8 */ -#define MMC_VDD_18_19 0x00000040/* VDD voltage 1.8 - 1.9 */ -#define MMC_VDD_19_20 0x00000080/* VDD voltage 1.9 - 2.0 */ +#define MMC_VDD_165_195 0x00000080/* VDD voltage 1.65 - 1.95 */ #define MMC_VDD_20_21 0x00000100/* VDD voltage 2.0 ~ 2.1 */ #define MMC_VDD_21_22 0x00000200/* VDD voltage 2.1 ~ 2.2 */ #define MMC_VDD_22_23 0x00000400/* VDD voltage 2.2 ~ 2.3 */
drivers/mmc/core/core.c static u32 mmc_select_voltage(struct mmc · line 317
Quoted 6 lines · Philip Langdale
drivers/mmc/core/core.c +0
-0@@ -317,6 +317,24 @@ static u32 mmc_select_voltage(struct mmc
The idea with the new structure is to keep a bare minimum of protocol information in core.c. So stick these tests into mmc.c and sd.c.
drivers/mmc/core/core.c static u32 mmc_select_voltage(struct mmc · line 339
Quoted 3 lines
drivers/mmc/core/core.c +2
-0+if (ocr &0x7F ) { + printk("%s: card claims to support voltages below "
Please include a level with the printk().
drivers/mmc/core/core.c static u32 mmc_select_voltage(struct mmc · line 339
Quoted 2 lines
drivers/mmc/core/core.c +1
-0+if (host->mode ==MMC_MODE_SD && (ocr &MMC_VDD_165_195 )) {
Ooops. host->mode should have been removed by now.
Otherwise the patch looks good. Just fix these points and I'll include it.
Rgds
Signature · 5 lines
-- Pierre Ossman Linux kernel, MMC maintainer http://www.kernel.org PulseAudio, core developer http://pulseaudio.org rdesktop, core developer http://www.rdesktop.org