lkml.org 
[lkml]   [2016]   [Aug]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 1/2] sdhci-of-arasan: Add quirk and device tree parameter to fake CD bit
    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

    \
     
     \ /
      Last update: 2016-09-17 09:57    [W:2.492 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site