From: Alexandre Courbot <acourbot@nvidia.com>
To: Tim Kryger <tim.kryger@gmail.com>
Cc: Sachin Kamat <spk.linux@gmail.com>,
Ulf Hansson <ulf.hansson@linaro.org>,
linux-mmc <linux-mmc@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Alexandre Courbot <gnurou@gmail.com>
Subject: Re: Possible regression with commit 52221610d
Date: Wed, 5 Nov 2014 17:10:42 +0900 [thread overview]
Message-ID: <5459DB82.9080100@nvidia.com> (raw)
In-Reply-To: <CAD7vxxLmLsRpxrYqc30nV0m6atO7jyNgv1Wh4R8GCAy3+y-1dw@mail.gmail.com>
On 11/05/2014 12:31 AM, Tim Kryger wrote:
> On Tue, Nov 4, 2014 at 1:00 AM, Alexandre Courbot <acourbot@nvidia.com> wrote:
>> Hi Tim, thanks for your reply!
>>
>> On 11/04/2014 02:28 PM, Tim Kryger wrote:
>>>
>>> On Mon, Nov 3, 2014 at 7:05 PM, Alexandre Courbot <acourbot@nvidia.com>
>>> wrote:
>>>>
>>>> Hi guys,
>>>>
>>>> On the NVIDIA shield (tegra114-roth) platform, I have noticed that MMC
>>>> stopped working completely on recent kernels. MMC devices will not show
>>>> up
>>>> and the message "mmc1: Controller never released inhibit bit(s)." shows
>>>> up
>>>> repeatedly in the console.
>>>>
>>>> After bisecting I tracked commit 52221610dd84dc3e9196554f0292ca9e8ab3541d
>>>> ("mmc: sdhci: Improve external VDD regulator support") as the one that
>>>> introduced this issue, which seems somehow surprising to me since it has
>>>> been around for a while and nobody else complained about this AFAICT.
>>>
>>>
>>> I'm not too familiar with the Nvidia Shield so can you please confirm
>>> the following?
>>>
>>> The controller in the Tegra114 is SDHCI compliant and as such
>>> sdhci_tegra_probe calls sdhci_add_host. External regulators are
>>> sought in sdhci_add_host with a call to mmc_regulator_get_supply.
>>
>>
>> This is correct.
>>
>>> Since no external regulators are specified in tegra114.dtsi or
>>> tegra114-roth.dts, mmc->supply.vmmc and mmc->supply.vqmmc are set to
>>> -ENODEV.
>>
>>
>> Actually 2 of the MMC nodes in tegra114-roth.dts (for SD card and eMMC) have
>> a vmmc-supply property, so for two of them at least mmc->supply.vmmc is a
>> valid pointer.
>>
>
> I must have been looking at an old version of the file. Thanks for
> clearing this up.
>
>> As explained above, vmmc is a valid pointer for 2 instances of the MMC
>> controller. Interestingly, if I just remove the "return" line in the
>> IS_ERR() block (without moving it around), the issue also seems to be fixed.
>>
>>>
>>> Can you provide the relevant parts of the log before the problem occurs?
>>
>>
>> There is not much unfortunately ; the only relevant log I have is this:
>>
>> [ 12.246022] mmc2: Timeout waiting for hardware interrupt.
>> [ 12.264990] mmc2: Controller never released inhibit bit(s).
>>
>> Some hardware interrupt timed out. I don't know much about the MMC
>> subsystem. but could it be because initially the controller is not in a
>> powered-on state, and that return statement causes the function to leave it
>> unpowered?
>
> In a nutshell, the issue here is that the SDHCI spec demands that VMMC
> be supplied by the controller itself with the specific voltage
> configured using the SDHCI_POWER_CONTROL register but almost nobody
> does this. Many SoCs omit this capability from their controllers and
> instead rely upon external regulators. In such cases there isn't
> normally any need to update the voltage bits of the power control
> register. It sounds like you are saying this isn't true for the
> Tegra114.
Thanks for your explanation, it makes sense now.
Looking at other Tegra boards .dts I noticed that SHIELD is the only one
using a vmmc-supply. Maybe this is the part that is wrong? I wrote this
DTS and cannot exclude I misread the schematics. Maybe that regulator is
used for some other (still sdmmc-related) purpose but the actual power
provider is the controller itself.
If you can confirm that the driver is performing as it should, I will
look in that direction and revise my DTS.
Thanks!
Alex.
next prev parent reply other threads:[~2014-11-05 8:11 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-04 3:05 Possible regression with commit 52221610d Alexandre Courbot
2014-11-04 5:28 ` Tim Kryger
2014-11-04 9:00 ` Alexandre Courbot
2014-11-04 15:31 ` Tim Kryger
2014-11-05 8:10 ` Alexandre Courbot [this message]
2014-11-05 15:27 ` Tim Kryger
2014-11-06 2:15 ` Alexandre Courbot
2014-12-14 7:22 ` Bjorn Andersson
2014-12-15 4:48 ` Tim Kryger
2014-12-16 6:27 ` Bjorn Andersson
2014-12-16 18:18 ` Bjorn Andersson
2014-12-17 6:20 ` Tim Kryger
2014-12-17 19:57 ` Bjorn Andersson
2014-12-22 3:01 ` Tim Kryger
2015-01-05 19:52 ` Bjorn Andersson
2015-01-12 10:31 ` Ulf Hansson
2015-01-13 16:00 ` Tim Kryger
2015-01-13 15:59 ` Tim Kryger
2015-01-14 5:00 ` Tim Kryger
2014-12-16 18:46 ` Stephen Warren
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5459DB82.9080100@nvidia.com \
--to=acourbot@nvidia.com \
--cc=gnurou@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mmc@vger.kernel.org \
--cc=spk.linux@gmail.com \
--cc=tim.kryger@gmail.com \
--cc=ulf.hansson@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).