Export DSR register through sysfs same as we did for the CID, CSD and
OCR registers.
Signed-off-by: Bojan Prtvar <prtvar.b@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Registers CID and CSD are already exported through sysfs so let's make
this interface complete by adding missing OCR register.
Signed-off-by: Bojan Prtvar <prtvar.b@gmail.com>
Reviewed-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Certain Hynix eMMC 4.41 cards might get broken when HPI feature is used
and hence this patch disables the HPI feature for such buggy cards.
As some of the other features like BKOPs/Cache/Sanitize are dependent on
HPI feature, those features would also get disabled if HPI is disabled.
Signed-off-by: Pratibhasagar V <pratibha@codeaurora.org>
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
[gdavis: Forward port and cleanup]
Signed-off-by: George G. Davis <george_davis@mentor.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
mmc_select_bus_width() returns bus width (4 or 8) on success or
zero if unsupported. So only change mode if setting the bus width
is successful.
Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
To slove the issue which was found on gru board for hs400.
[ 4.616946] sdhci: Secure Digital Host Controller Interface driver
[ 4.623135] sdhci: Copyright(c) Pierre Ossman
[ 4.722575] sdhci-pltfm: SDHCI platform and OF driver helper
[ 4.730962] sdhci-arasan fe330000.sdhci: No vmmc regulator found
[ 4.737444] sdhci-arasan fe330000.sdhci: No vqmmc regulator found
[ 4.774930] mmc0: SDHCI controller on fe330000.sdhci [fe330000.sdhci] using ADMA
[ 4.980295] mmc0: switch to high-speed from hs200 failed, err:-84
[ 4.986487] mmc0: error -84 whilst initialising MMC card
We should change HS400 mode selection timing to meet JEDEC
specification. The JEDEC 5.1 said that change the frequency to <= 52MHZ
after HS_TIMING switch. Refer to section 6.6.2.3 "HS400" timing mode
selection:
Set the "Timing Interface" parameter in the HS_TIMING[185] field of the
Extended CSD register to 0x1 to switch to High Speed mode and then set
the clock frequency to a value not greater than 52MHZ.
Signed-off-by: Ziyuan Xu <xzy.xu@rock-chips.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Per JEDEC spec, it is not recommended to use CMD13 to get card status
after speed mode switch. below are two reason about this:
1. CMD13 cannot be guaranteed due to the asynchronous operation.
Therefore it is not recommended to use CMD13 to check busy completion
of the timing change indication.
2. After switch to HS200, CMD13 will get response of 0x800, and even the
busy signal gets de-asserted, the response of CMD13 is aslo 0x800.
Signed-off-by: Chaotian Jing <chaotian.jing@mediatek.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Controllers use data strobe line to latch data from devices
under hs400 mode, but not for cmd line. So since emmc 5.1, JEDEC
introduces enhanced strobe mode for latching cmd response from
emmc devices to host controllers. This new feature is optional,
so it depends both on device's cap and host's cap to decide
whether to use it or not.
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Tested-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Jaehoon Chung <jh80.chung@samsung.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
When IS_ERR_VALUE was removed from the mmc core code, it was replaced
with a simple not-zero check. This does not work, as the value checked
is the return value for mmc_select_bus_width, which returns the set
bit width on success. This made eMMC modes higher than HS-DDR unusable.
Fix this by checking for a positive return value instead.
Fixes: 287980e49f ("remove lots of IS_ERR_VALUE abuses")
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>
Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Tested-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Most users of IS_ERR_VALUE() in the kernel are wrong, as they
pass an 'int' into a function that takes an 'unsigned long'
argument. This happens to work because the type is sign-extended
on 64-bit architectures before it gets converted into an
unsigned type.
However, anything that passes an 'unsigned short' or 'unsigned int'
argument into IS_ERR_VALUE() is guaranteed to be broken, as are
8-bit integers and types that are wider than 'unsigned long'.
Andrzej Hajda has already fixed a lot of the worst abusers that
were causing actual bugs, but it would be nice to prevent any
users that are not passing 'unsigned long' arguments.
This patch changes all users of IS_ERR_VALUE() that I could find
on 32-bit ARM randconfig builds and x86 allmodconfig. For the
moment, this doesn't change the definition of IS_ERR_VALUE()
because there are probably still architecture specific users
elsewhere.
Almost all the warnings I got are for files that are better off
using 'if (err)' or 'if (err < 0)'.
The only legitimate user I could find that we get a warning for
is the (32-bit only) freescale fman driver, so I did not remove
the IS_ERR_VALUE() there but changed the type to 'unsigned long'.
For 9pfs, I just worked around one user whose calling conventions
are so obscure that I did not dare change the behavior.
I was using this definition for testing:
#define IS_ERR_VALUE(x) ((unsigned long*)NULL == (typeof (x)*)NULL && \
unlikely((unsigned long long)(x) >= (unsigned long long)(typeof(x))-MAX_ERRNO))
which ends up making all 16-bit or wider types work correctly with
the most plausible interpretation of what IS_ERR_VALUE() was supposed
to return according to its users, but also causes a compile-time
warning for any users that do not pass an 'unsigned long' argument.
I suggested this approach earlier this year, but back then we ended
up deciding to just fix the users that are obviously broken. After
the initial warning that caused me to get involved in the discussion
(fs/gfs2/dir.c) showed up again in the mainline kernel, Linus
asked me to send the whole thing again.
[ Updated the 9p parts as per Al Viro - Linus ]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.org/lkml/2016/1/7/363
Link: https://lkml.org/lkml/2016/5/27/486
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> # For nvmem part
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some eMMCs set the partition switch timeout too low.
Now typically eMMCs are considered a critical component (e.g. because
they store the root file system) and consequently are expected to be
reliable. Thus we can neglect the use case where eMMCs can't switch
reliably and we might want a lower timeout to facilitate speedy
recovery.
Although we could employ a quirk for the cards that are affected (if
we could identify them all), as described above, there is little
benefit to having a low timeout, so instead simply set a minimum
timeout.
The minimum is set to 300ms somewhat arbitrarily - the examples that
have been seen had a timeout of 10ms but were sometimes taking 60-70ms.
Cc: stable@vger.kernel.org
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
mmc_select_hs200() and mmc_select_hs() will keep the timing
as before if switch fails. So it's meaningless to print the
failed switched mode outside based on the current host timing.
Furthermore, the original print is wrong, it should be:
pr_warn("%s: switch to %s failed\n",
mmc_hostname(card->host),
mmc_card_hs(card) ? "high-speed" :
(mmc_card_hs200(card) ? "hs200" : ""));
Since we already have error message in mmc_select_hs200(),
simply remove it outside.
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Currently MMC core will keep going if HS200/HS timing switch failed
with -EBADMSG error by the assumption that the old timing is still valid.
However, for mmc_select_hs200 case, the signal voltage may have already
been switched. If the timing switch failed, we should fall back to
the old voltage in case the card is continue run with legacy timing.
If fall back signal voltage failed, we explicitly report an EIO error
to force retry during the next power cycle.
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
CMD0 or hardware reset may invalidate the cache, so it needs to be
flushed before reset.
In the case of recovery, we can't expect flushing the cache to work
always, but have a go and ignore errors.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This if-block is going to call mmc_card_set_blockaddr(), so
mmc_card_blockaddr() right before it is redundant.
I am fixing the block comment style while I am here.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
The eMMC HW reset may be implemented either via the host ops ->hw_reset()
callback or through DT and the eMMC pwrseq. Additionally some eMMC cards
don't support HW reset.
To allow a reset to be done for the different combinations of mmc hosts
and eMMC/MMC cards, let's implement a fallback via trying a regular power
cycle. This improves the mmc block layer retry mechanism of failing I/O
requests.
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
[Ulf: Rewrote changelog]
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
The bus width is sometimes the actual bus width, and sometimes indices
to different arrays encoding the bus width. In my debugging case "2"
could mean 8-bit as well as 4-bit, which was extremly confusing. Let's
use the human-readable actual bus width in all places.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
IMO this info is only useful for developers. Most users won't need this
information, since there is not much they can do about it.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
A card can be removed while it is runtime suspended.
Do not print an error message.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Commit cc4f414c88 ("mmc: mmc: Add driver strength selection")
added driver strength selection for eMMC HS200 and HS400 modes.
That patch also set the driver stength when transitioning through
High Speed mode to HS200/HS400, but driver strength is not defined
for High Speed mode. While the JEDEC specification is not clear
on this point it has been observed to cause problems for some eMMC,
and removing the driver strength setting in this case makes it
consistent with the normal use of High Speed mode.
Signed-off-by: Wenkai Du <wenkai.du@intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@vger.kernel.org # v4.2+
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
MMC_CAP_RUNTIME_RESUME was invented to decrease system PM resume time for
systems that particularly needs this. As the feature has matured let's
make it the default behavior for MMC/SD.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
mmc_select_hs400() calls __mmc_switch() which checks the switch is
successful using CMD13 (SEND_STATUS). The problem is that it does that
using the timing settings of the previous mode. That is prone to error,
especially when switching from HS to HS400 because the timing parameters
for HS mode are tighter than the timing parameters for HS400 mode.
In the case when CMD13 polling is used (i.e. not MMC_CAP_WAIT_WHILE_BUSY)
with the switch command, it must be assumed that using different modes on
the card and host must work.
However in the case when CMD13 polling is not used
(i.e. MMC_CAP_WAIT_WHILE_BUSY) mmc_select_hs400() can be made more
reliable by setting the host to the correct timing before sending CMD13.
This patch does that.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: <stable@vger.kernel.org> # 4.2+
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Move the mmc_switch_status() function in preparation for calling it
in mmc_select_hs400().
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: <stable@vger.kernel.org> # 4.2+
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
mmc_select_hs400() begins with the card and host in HS200 mode.
Therefore, any commands sent to the card should use HS200 timing.
It is incorrect to set the host to High Speed (HS) timing before
sending the switch command. Doing so is unreliable because
the timing parameters for HS mode are tighter than the timing
parameters for HS200 mode. Thus the HS timings should be set
only after the card has switched mode.
However, it is not unreasonable first to reduce the frequency to
the HS mode frequency, which should make the switch command and
subsequent CMD13 commands more reliable.
This patch does that.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: <stable@vger.kernel.org> # 4.2+
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Currently mmc_select_hs200() uses __mmc_switch() which checks the
success of the switch to HS200 mode using CMD13 (SEND_STATUS).
The problem is that it does that using the timing settings of legacy
mode. That is prone to error, not least because the timing parameters
for legacy mode are tighter than the timing parameters for HS200 mode.
In the case when CMD13 polling is used (i.e. not MMC_CAP_WAIT_WHILE_BUSY)
with the switch command, it must be assumed that using different modes on
the card and host must work.
However in the case when CMD13 polling is not used
(i.e. MMC_CAP_WAIT_WHILE_BUSY) mmc_select_hs200() can be made more
reliable by setting the host to the correct timing before sending CMD13.
This patch does that.
A complication is that the caller, mmc_select_timing(), will ignore a
switch error (indicated by -EBADMSG), assume the old mode is valid
and continue, so the old timing must be restored in that case.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: <stable@vger.kernel.org> # 4.2+
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
There's little sense in releasing the host on mmc_add_card() error
immediately after reclaiming it, so reclaim the host only in case
of success.
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
MMC_CLKGATE was once invented to save power by gating the bus clock at
request inactivity. At that time it served its purpose. The modern way to
deal with power saving for these scenarios, is by using runtime PM.
Nowadays, several host drivers have deployed runtime PM, but for those
that haven't and which still cares power saving at request inactivity,
it's certainly time to deploy runtime PM as it has been around for several
years now.
To simplify code to mmc core and thus decrease maintenance efforts, this
patch removes all code related to MMC_CLKGATE.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Suppose that we got a data crc error, and it triggers the mmc_reset.
mmc_reset will call mmc_send_status to see if HW reset was supported.
before issue CMD13, it will do retune, and if EMMC was in HS400 mode,
it will reduce frequency to 52Mhz firstly, then results in card init
was doing at 52Mhz.
The mmc_send_status was originally only done for mmc_test, should drop
it. And, rename the "eMMC hardware reset" to "Reset test", as we would
also be able to use the test for SD-cards.
Signed-off-by: Chaotian Jing <chaotian.jing@mediatek.com>
Suggested-by: Adrian Hunter <adrian.hunter@intel.com>
Fixes: bd11e8bd03 ("mmc: core: Flag re-tuning is needed on CRC errors")
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Since the ->reset() callback is implemented for MMC, the ->power_restore()
callback has become redundant, let's remove it.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Add the ability to set eMMC driver strength
for HS200 and HS400.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
In preparation for supporing drive strength selection
for eMMC, read the card's valid driver strengths.
Note that though the SD spec uses the term "drive strength",
the JEDEC eMMC spec uses the term "driver strength".
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
card->ext_csd.enhanced_area_offset is defined as "unsigned long long",
and, ext_csd[] is defined as u8.
unsigned long long data might have strange data if first bit of ext_csd[]
was 1. this patch cast it to (unsigned long long)
Special thanks to coverity <http://www.coverity.com>
ex)
u8 data8;
u64 data64;
data8 = 0x80;
data64 = (data8 << 24); // 0xffffffff80000000
data64 = (((unsigned long long)data8) << 24); // 0x80000000;
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
HS400 re-tuning must be done in HS200 mode. Add
the ability to switch from HS400 mode to HS200
mode before re-tuning and switch back to HS400
after re-tuning.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
The sleep command is issued after deselecting the
card, but re-tuning won't work on a deselected card
so re-tuning must be held.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Pull trivial tree from Jiri Kosina:
"Usual trivial tree updates. Nothing outstanding -- mostly printk()
and comment fixes and unused identifier removals"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial:
goldfish: goldfish_tty_probe() is not using 'i' any more
powerpc: Fix comment in smu.h
qla2xxx: Fix printks in ql_log message
lib: correct link to the original source for div64_u64
si2168, tda10071, m88ds3103: Fix firmware wording
usb: storage: Fix printk in isd200_log_config()
qla2xxx: Fix printk in qla25xx_setup_mode
init/main: fix reset_device comment
ipwireless: missing assignment
goldfish: remove unreachable line of code
coredump: Fix do_coredump() comment
stacktrace.h: remove duplicate declaration task_struct
smpboot.h: Remove unused function prototype
treewide: Fix typo in printk messages
treewide: Fix typo in printk messages
mod_devicetable: fix comment for match_flags
The eMMC on a tablet I've will stop working / communicating as soon as
the kernel executes:
mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
EXT_CSD_HPI_MGMT, 1,
card->ext_csd.generic_cmd6_time);
There seems to be no way to reliable identify eMMC-s which have a broken
hpi implementation, but at least for eMMC's which are soldered onto a board
we can work around this by specifying that hpi is broken in devicetree.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This patch is coming to fix compatibility issue of BKOPS_EN field of EXT_CSD.
In eMMC-5.1, BKOPS_EN was changed, and now it has two operational bits:
Bit 0 - MANUAL_EN
Bit 1 - AUTO_EN
In previous eMMC revisions, only Bit 0 was supported.
Signed-off-by: Alexey Skidanov <alexey.skidanov@sandisk.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
For each MMC, SD and SDIO there is code that
holds the clock, calls ops->execute_tuning, and
releases the clock. Simplify the code a bit by
providing a separate function to do that.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Move the (e)MMC specific hw_reset code from core.c into mmc.c. Call the
code from the new bus_ops member "reset". This also allows for adding
a SD card specific reset procedure.
Signed-off-by: Johan Rudholm <johanru@axis.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Since previous patches removed the need for the tuning block patterns
to be exported, let's move them close to the mmc_send_tuning() API.
Those are now intended to be used only by the mmc core.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
In (3fcb027 ARM: MXC: mxcmmc: work around a bug in the SDHC busy line
handling) the optional init_card() callback was added. According to
the original change it was "for now only called from
mmc_sdio_init_card()".
This callback really ought to be called from the SD and MMC init
functions as well. One current user of this callback
(mxcmci_init_card) will not work as expected if you insert an SDIO
card, then eject it and put a normal SD card in. Specifically the
normal SD card will not get to run with 4-bit data.
I'd like to use the init_card() callback to handle a similar quirk on
dw_mmc when using SDIO Interrupts (the "low power" feature of the card
needs to be disabled), so that will add a second user of the function.
Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Grant Grundler <grundler@chromium.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
mmc_select_bus_width() will try to switch to MMC_BUS_WIDTH_4 even if
MMC_CAP_4_BIT_DATA and MMC_CAP_8_BIT_DATA are not set in host->caps.
Return as soon as possible when those flags are not set
Fixes: 577fb13199 (mmc: rework selection of bus speed mode)
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Cc: <stable@vger.kernel.org> # 3.17
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Callers of mmc_send_ext_csd() will be able to decrease code duplication
by using mmc_get_ext_csd() instead. Let's make it available.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
The callers of mmc_get_ext_csd() need the flexibility to handle errors
themselves, because they behave differently.
Let's clean up mmc_get_ext_csd() with its friends and adopt the error
handling as stated above.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
As a step in cleaning up code around reading/decoding EXT_CSD, convert
the current mmc_read_ext_csd(), to handle both fetching the EXT_CSD
and decoding its data.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
The helper function mmc_can_ext_csd() will return a positive value if
the card supports the EXT_CSD register. Start using it at relavant
places in the mmc core.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
If the MMC spec version is < CSD_SPEC_VER_4, there aren't support for
the EXT_CSD register. Since max_dtr is fetched from there, it will
default to zero, which thus isn't needed to verify.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
The validation of the buswidth and the MMC spec version in
__mmc_select_powerclass() is redundant, let's remove it.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>