Wei.zeng: Created page with "SD/MMC cards which use the MMC subsystem are available as block device through /dev/mmcblk{id}. The kernel normally parses the partition table and exports the partitions of th..."

2020-03-20T05:56:31Z

Created page with "SD/MMC cards which use the MMC subsystem are available as block device through /dev/mmcblk{id}. The kernel normally parses the partition table and exports the partitions of th..."

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SD/MMC cards which use the MMC subsystem are available as block device through /dev/mmcblk{id}. The kernel normally parses the partition table and exports the partitions of the card using the appendix p{x}, e.g. /dev/mmcblk{id}p{x}.

= [https://developer.toradex.cn/knowledge-base/sd-mmc-card-(linux)#sdmmc-driver-initialisation SD/MMC driver initialisation] =

The following bootlog shows the detection of a SDHCI controller:
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); width: 1007px; height: 144px; color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">root@:~# dmesg | egrep "(sdhci|mmc)"
[ 1.880782] sdhci: Secure Digital Host Controller Interface driver
[ 1.890679] sdhci: Copyright(c) Pierre Ossman
[ 1.898540] sdhci-pltfm: SDHCI platform and OF driver helper
[ 1.909980] sdhci-esdhc-imx 2190000.usdhc: Got CD GPIO
[ 1.984346] mmc0: SDHCI controller on 2190000.usdhc [2190000.usdhc] using ADMA
</pre>

Before inserting any card no interrupts are generated yet:
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">root@:~# cat /proc/interrupts | egrep "(mmc|cd)"
58: 0 GPC 22 Level mmc0
200: 0 gpio-mxc 0 Edge 2190000.usdhc cd
</pre>

And the IOs debugging information is not valid yet:
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">root@:~# cat /sys/kernel/debug/mmc0/ios
clock: 0 Hz
vdd: 0 (invalid)
bus mode: 2 (push-pull)
chip select: 0 (don't care)
power mode: 0 (off)
bus width: 0 (1 bits)
timing spec: 0 (legacy)
signal voltage: 0 (3.30 V)
driver type: 0 (driver type B)
</pre>

With the MMC_CD card detection GPIO pin still being pulled-up:
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">root@:~# cat /sys/kernel/debug/gpio | grep cd
gpio-128 ( |cd ) in hi IRQ
</pre>

== [https://developer.toradex.cn/knowledge-base/sd-mmc-card-(linux)#sdmmc-card-insertion SD/MMC Card Insertion] ==

On insertion, the kernel starts scanning the card in order to create devices for each partition. Depending on the Automount configuration the detected file systems get mounted automatically.
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">[ 286.140413] mmc0: new high speed SDHC card at address 0007
[ 286.150926] mmcblk0: mmc0:0007 SDCIT 7.29 GiB
[ 286.170497] mmcblk0: p1 p2
[ 287.691840] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
</pre>

Interrupts are happening (note one card detect GPIO interrupt thereof):
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">root@:~# cat /proc/interrupts | egrep "(mmc|cd)"
58: 375 GPC 22 Level mmc0
200: 1 gpio-mxc 0 Edge 2190000.usdhc cd
</pre>

And the IOs debugging information should now show valid information about the inserted card:
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">root@:~# cat /sys/kernel/debug/mmc0/ios
clock: 50000000 Hz
actual clock: 49500000 Hz
vdd: 21 (3.3 ~ 3.4 V)
bus mode: 2 (push-pull)
chip select: 0 (don't care)
power mode: 2 (on)
bus width: 2 (4 bits)
timing spec: 2 (sd high-speed)
signal voltage: 0 (3.30 V)
driver type: 0 (driver type B)
</pre>

With the MMC_CD card detection GPIO pin now being pulled to ground:
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">root@:~# cat /sys/kernel/debug/gpio | grep cd
gpio-128 ( |cd ) in lo IRQ
</pre>

More specifics about the inserted card can be found in its CID/CSD:
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">root@:~# cat /sys/bus/mmc/devices/mmc0\:0007/cid
413432534443495430002e35cf012800
root@:~# cat /sys/bus/mmc/devices/mmc0\:0007/csd
400e00325b5900003a4f7f800a400000
</pre>

The utility df shows the usage of the SD/MMC card:
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">root@:~# df | grep mmc
/dev/mmcblk0p2 1467980 903468 470664 66% /media/mmcblk0p2
/dev/mmcblk0p1 85010 22894 62116 27% /media/mmcblk0p1
</pre>

And mount shows the mounting status:
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">root@:~# mount | grep mmc
/dev/mmcblk0p2 on /media/mmcblk0p2 type ext4 (rw,relatime,data=ordered)
/dev/mmcblk0p1 on /media/mmcblk0p1 type vfat (rw,relatime,gid=6,fmask=0007,dmask=0007,allow_utime=0020,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)
</pre>

From regular SD cards one should be able to read with sustained data rates of around 10 to 20 MB/sec:
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">root@:~# hdparm -t /dev/mmcblk0

/dev/mmcblk0:
Timing buffered disk reads: 66 MB in 3.04 seconds = 21.70 MB/sec
</pre>

== [https://developer.toradex.cn/knowledge-base/sd-mmc-card-(linux)#sdmmc-card-removal SD/MMC Card Removal] ==

Kernel message:
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">[ 441.027332] mmc0: card 0007 removed
</pre>

Triggered by another card detection interrupt:
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">root@:~# cat /proc/interrupts | egrep "(mmc|cd)"
58: 641 GPC 22 Level mmc0
200: 2 gpio-mxc 0 Edge 2190000.usdhc cd
</pre>

How to use SD/MMC Card for Diagnostic - Revision history

Wei.zeng: Created page with "SD/MMC cards which use the MMC subsystem are available as block device through /dev/mmcblk{id}. The kernel normally parses the partition table and exports the partitions of th..."