MMC: Clean up low voltage range handling
PATCH 1/1 MMC: Clean up low voltage range handling
Clean up the handling of low voltage MMC cards.
The latest MMC and SD specs both agree that the low voltage range is defined as 1.65-1.95V and is signified by bit 7 in the OCR. An old Sandisk spec implied that bits 7-0 represented voltages below 2.0V in 1V 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 6) resulting in the the low voltage mode never being used.
This change switches the code to conform to the specs and fixes the SDHCI driver. It also removes the explicit defines for the host vdd and updates the SDHCI driver to convert the bit number back to the mask value for comparisons. Having only a single set of defines ensures there's nothing to get out of sync.
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 +7 -11
@@ -668,20 +668,16 @@ static void sdhci_set_power(struct sdhci pwr =SDHCI_POWER_ON ; -switch (power) { -case MMC_VDD_170 : -case MMC_VDD_180 : -case MMC_VDD_190 : +switch (1 << power) { +case MMC_VDD_165_195 : pwr |=SDHCI_POWER_180 ;break ; -case MMC_VDD_290 : -case MMC_VDD_300 : -case MMC_VDD_310 : +case MMC_VDD_29_30 : +case MMC_VDD_30_31 : pwr |=SDHCI_POWER_300 ;break ; -case MMC_VDD_320 : -case MMC_VDD_330 : -case MMC_VDD_340 : +case MMC_VDD_32_33 : +case MMC_VDD_33_34 : pwr |=SDHCI_POWER_330 ;break ;default :
@@ -1293,7 +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 +2 -32
@@ -16,30 +16,7 @@ struct mmc_ios {unsigned int clock;/* clock rate */ unsigned short vdd; -#define MMC_VDD_150 0 -#define MMC_VDD_155 1 -#define MMC_VDD_160 2 -#define MMC_VDD_165 3 -#define MMC_VDD_170 4 -#define MMC_VDD_180 5 -#define MMC_VDD_190 6 -#define MMC_VDD_200 7 -#define MMC_VDD_210 8 -#define MMC_VDD_220 9 -#define MMC_VDD_230 10 -#define MMC_VDD_240 11 -#define MMC_VDD_250 12 -#define MMC_VDD_260 13 -#define MMC_VDD_270 14 -#define MMC_VDD_280 15 -#define MMC_VDD_290 16 -#define MMC_VDD_300 17 -#define MMC_VDD_310 18 -#define MMC_VDD_320 19 -#define MMC_VDD_330 20 -#define MMC_VDD_340 21 -#define MMC_VDD_350 22 -#define MMC_VDD_360 23 +/* vdd stores the bit number of the selected voltage range from protocol.h */ unsigned char bus_mode;/* command output mode */
@@ -88,14 +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 */
Quoted 10 lines · Philip Langdale
Clean up the handling of low voltage MMC cards.
The latest MMC and SD specs both agree that the low voltage range is defined as 1.65-1.95V and is signified by bit 7 in the OCR. An old Sandisk spec implied that bits 7-0 represented voltages below 2.0V in 1V increments, and the code was accordingly written with that expectation.
We must not have the same specs. My simplified SD 2.0 physical spec defines everything below bit 15 as reserved.
Quoted 8 lines
This change switches the code to conform to the specs and fixes the SDHCI driver. It also removes the explicit defines for the host vdd and updates the SDHCI driver to convert the bit number back to the mask value for comparisons. Having only a single set of defines ensures there's nothing to get out of sync.
Although this is a nice change, it confuses things to have two changes in one commit. Could you split them up and base it on my "for-andrew" branch?
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
Quoted 3 lines · Pierre Ossman
We must not have the same specs. My simplified SD 2.0 physical spec defines everything below bit 15 as reserved.
I was a little unclear. Both specs define bit 7 as the low-voltage range but only the MMC spec defines the actual voltage. As such, there is no complete definition of a low voltage SD card. That's why I added the sanity check in the actual code.
Quoted 3 lines
Although this is a nice change, it confuses things to have two changes in one commit. Could you split them up and base it on my "for-andrew" branch?
Yeah, I thought you'd think that :-) I'll post the two diffs shortly.
Thanks,
--phil