From: "Sören Brinkmann" <soren.brinkmann@xilinx.com>
To: Lars-Peter Clausen <lars@metafoo.de>
Cc: Zach Brown <zach.brown@ni.com>, <mark.rutland@arm.com>,
<devicetree@vger.kernel.org>, <ulf.hansson@linaro.org>,
<linux-mmc@vger.kernel.org>, <adrian.hunter@intel.com>,
<linux-kernel@vger.kernel.org>, <robh+dt@kernel.org>,
<michal.simek@xilinx.com>, <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 1/2] sdhci-of-arasan: Add quirk and device tree parameter to fake CD bit
Date: Thu, 25 Aug 2016 08:29:44 -0700 [thread overview]
Message-ID: <20160825152944.GP16583@xsjsorenbubuntu> (raw)
In-Reply-To: <d5dd97b1-f58f-2e45-5c95-17a77a46b30c@metafoo.de>
On Thu, 2016-08-25 at 17:23:47 +0200, Lars-Peter Clausen wrote:
> On 08/25/2016 05:10 PM, Sören Brinkmann wrote:
> > On Wed, 2016-08-24 at 18:23:03 -0500, Zach Brown wrote:
> >> The sdhci controller on xilinx zynq devices will not function unless
> >> the cd bit is provided. http://www.xilinx.com/support/answers/61064.html
> >> In cases where it is impossible to provide the cd bit in hardware,
> >> setting the controller to test mode and then setting inserted to true
> >> will get the controller to function with out the cd bit.
> >>
> >> The device property "fake-cd" will let the arasan driver know it needs
> >> to fake the cd bit for the controller inorder for the controller to
> >> function with a SD card that does not provide the CD bit.
> >
> > I thought the CD is, if not pinned out, tied off to some valid logic
> > level. Isn't it enough to specify cd-inverted if needed to make it work
> > in those cases?
>
> It is always brought out to some pin, that is the problem on the Zynq. This
> means you'd have to set at least one pin aside as dummy CD or WP pin. Which
> is not always possible when you are tight on available pins.
I have to admit that I haven't looked at Vivado for quite a while. Is it
possible to select EMIO for those pins? If those are not routed anything
they should be tied to some logic level, I believe.
If they are always forced to be on a physical pin, do you let that pin
just float? Otherwise, the logic level should also be defined, give and
take a logic inversion.
Sören
next prev parent reply other threads:[~2016-08-26 1:12 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-24 23:23 [PATCH 1/2] sdhci-of-arasan: Add quirk and device tree parameter to fake CD bit Zach Brown
2016-08-24 23:23 ` [PATCH 2/2] " Zach Brown
2016-08-25 6:56 ` kbuild test robot
2016-08-25 8:50 ` Adrian Hunter
2016-08-25 10:37 ` Lars-Peter Clausen
2016-08-25 10:56 ` [PATCH 1/2] " Mark Rutland
2016-08-25 17:15 ` Zach Brown
2016-08-25 18:10 ` Mark Rutland
2016-08-25 18:26 ` Zach Brown
2016-08-25 18:28 ` Mark Rutland
2016-08-25 20:46 ` Zach Brown
2016-08-26 7:42 ` Ulf Hansson
2016-08-26 22:29 ` Zach Brown
2016-08-29 11:21 ` Ulf Hansson
2016-08-25 15:10 ` Sören Brinkmann
2016-08-25 15:23 ` Lars-Peter Clausen
2016-08-25 15:29 ` Sören Brinkmann [this message]
2016-08-25 15:50 ` Lars-Peter Clausen
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