[PATCH v2 4/8] mmc: dw_mmc: Use mmc_regulator_set_vqmmc in start_signal_voltage_switch

Kevin Hilman khilman at kernel.org
Fri Oct 9 13:17:49 PDT 2015

On Fri, Oct 9, 2015 at 10:12 PM, Doug Anderson <dianders at chromium.org> wrote:
> Kevin,
> On Fri, Oct 9, 2015 at 12:06 PM, Kevin Hilman <khilman at kernel.org> wrote:
>> On Wed, Sep 30, 2015 at 4:07 PM, Heiko Stuebner <heiko at sntech.de> wrote:
>>> From: Douglas Anderson <dianders at chromium.org>
>>> We've introduced a new helper in the MMC core:
>>> mmc_regulator_set_vqmmc().  Let's use this in dw_mmc.  Using this new
>>> helper has some advantages:
>>> 1. We get the mmc_regulator_set_vqmmc() behavior of trying to match
>>>    VQMMC and VMMC when the signal voltage is 3.3V.  This ensures max
>>>    compatibility.
>>> 2. We get rid of a few more warnings when probing unsupported
>>>    voltages.
>>> 3. We get rid of some non-dw_mmc specific code in dw_mmc.
>>> Signed-off-by: Douglas Anderson <dianders at chromium.org>
>>> Signed-off-by: Heiko Stuebner <heiko at sntech.de>
>> kernelci.org found a new failure in linux-next on
>> exynos5800-peach-pi[1] and it was bisected down to this patch, which
>> has hit linux-next in the form of commit fba2e23128d0 (mmc: dw_mmc:
>> Use mmc_regulator_set_vqmmc in start_signal_voltage_switch).  Based on
>> a quick glance at the boot log[2], it looks to be a bad pointer
>> dereference in regulator_get_voltage().
>> I confirmed that reverting this patch on top of next-20151009 gets my
>> peach-pi booting again.
>> Note that the boot failure is only on exynos_defconfig, not multi_v7_defconfig.
> Right.  See <http://www.spinics.net/lists/arm-kernel/msg450802.html>
> for discussion.  Ulf responded to the cover letter rather than the
> individual patch.

Ah, I hadn't noticed that.  Thanks.

I guess it should be dropped by tomorrow's linux-next then.  I'll keep
an eye on it.


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