From: Adrian Hunter <adrian.hunter-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
To: Zach Brown <zach.brown-acOepvfBmUk@public.gmane.org>
Cc: ulf.hansson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org,
mark.rutland-5wv7dgnIgG8@public.gmane.org,
robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
linux-mmc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] sdhci: Add quirk and device tree parameter to force SD test mode
Date: Wed, 24 Aug 2016 09:16:48 +0300 [thread overview]
Message-ID: <bd59af70-ebd8-2c92-e6ab-e1f0bf9acce7@intel.com> (raw)
In-Reply-To: <20160823221421.GB20351@zach-desktop>
On 24/08/16 01:14, Zach Brown wrote:
> On Tue, Aug 23, 2016 at 09:22:29AM +0300, Adrian Hunter wrote:
>> On 23/08/16 01:55, Zach Brown wrote:
>>> From: Jaeden Amero <jaeden.amero-acOepvfBmUk@public.gmane.org>
>>>
>>> On some devices, CD is broken so that we must force the SDHCI into test
>>> mode and set CD, so that it always detects an SD card as present.
>>>
>>> In order to get a device with broken CD working, we had previously
>>> always set the SDHCI into test mode. Unfortunately, this had the side
>>> effect of making all SD cards used with our Linux kernels undetectable
>>> and non-removable.
>>>
>>> By making this "SD test mode" setting optional via a quirk, we can avoid
>>> this side effect for devices other than the device with broken CD.
>>> Additionally, we add a device parameter to sdhci-pltfm to allow all
>>> SDHCI drivers to enable this quirk.
>>
>> Generally new quirks are not acceptable, but I don't see how test mode helps
>> very much since you still don't get any card detection events. If you
>> really need test mode, please explain more about how it helps (as opposed to
>> polling for example).
>>
>>
>
> Polling doesnt work in our case, since the issue lies with the SD controller
> itself. The SD controller in xilinx zynq devices requires the CDn signal to
> work. http://www.xilinx.com/support/answers/61064.html We have a situation
> where the controller requires the signal, but we can't use any of our pins to
> supply it. With test mode we can get the controller into a state where it works
> despite not having the signal.
>
Doesn't sound like something we need in sdhci.c. Have you considered adding
it to the driver, perhaps using the ->reset() callback?
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WARNING: multiple messages have this Message-ID (diff)
From: Adrian Hunter <adrian.hunter@intel.com>
To: Zach Brown <zach.brown@ni.com>
Cc: ulf.hansson@linaro.org, mark.rutland@arm.com, robh+dt@kernel.org,
linux-mmc@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sdhci: Add quirk and device tree parameter to force SD test mode
Date: Wed, 24 Aug 2016 09:16:48 +0300 [thread overview]
Message-ID: <bd59af70-ebd8-2c92-e6ab-e1f0bf9acce7@intel.com> (raw)
In-Reply-To: <20160823221421.GB20351@zach-desktop>
On 24/08/16 01:14, Zach Brown wrote:
> On Tue, Aug 23, 2016 at 09:22:29AM +0300, Adrian Hunter wrote:
>> On 23/08/16 01:55, Zach Brown wrote:
>>> From: Jaeden Amero <jaeden.amero@ni.com>
>>>
>>> On some devices, CD is broken so that we must force the SDHCI into test
>>> mode and set CD, so that it always detects an SD card as present.
>>>
>>> In order to get a device with broken CD working, we had previously
>>> always set the SDHCI into test mode. Unfortunately, this had the side
>>> effect of making all SD cards used with our Linux kernels undetectable
>>> and non-removable.
>>>
>>> By making this "SD test mode" setting optional via a quirk, we can avoid
>>> this side effect for devices other than the device with broken CD.
>>> Additionally, we add a device parameter to sdhci-pltfm to allow all
>>> SDHCI drivers to enable this quirk.
>>
>> Generally new quirks are not acceptable, but I don't see how test mode helps
>> very much since you still don't get any card detection events. If you
>> really need test mode, please explain more about how it helps (as opposed to
>> polling for example).
>>
>>
>
> Polling doesnt work in our case, since the issue lies with the SD controller
> itself. The SD controller in xilinx zynq devices requires the CDn signal to
> work. http://www.xilinx.com/support/answers/61064.html We have a situation
> where the controller requires the signal, but we can't use any of our pins to
> supply it. With test mode we can get the controller into a state where it works
> despite not having the signal.
>
Doesn't sound like something we need in sdhci.c. Have you considered adding
it to the driver, perhaps using the ->reset() callback?
next prev parent reply other threads:[~2016-08-24 6:16 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-22 22:55 [PATCH] sdhci: Add quirk and device tree parameter to force SD test mode Zach Brown
2016-08-23 2:46 ` Frank Rowand
2016-08-23 22:19 ` Zach Brown
2016-08-23 22:19 ` Zach Brown
[not found] ` <1471906531-28668-1-git-send-email-zach.brown-acOepvfBmUk@public.gmane.org>
2016-08-23 1:34 ` Haibo Chen
2016-08-23 1:34 ` Haibo Chen
2016-08-23 22:04 ` Zach Brown
2016-08-23 6:22 ` Adrian Hunter
2016-08-23 6:22 ` Adrian Hunter
2016-08-23 22:14 ` Zach Brown
2016-08-23 22:14 ` Zach Brown
2016-08-24 6:16 ` Adrian Hunter [this message]
2016-08-24 6:16 ` Adrian Hunter
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