On Thu, Aug 25, 2016 at 11:56:55AM +0100, Mark Rutland wrote: > On Wed, Aug 24, 2016 at 06:23:03PM -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 > > Nit: s/inorder/in order/ > > Comments on the actual patch below. > > > function with a SD card that does not provide the CD bit. > > > > Signed-off-by: Zach Brown <zach.brown@xxxxxx> > > --- > > Documentation/devicetree/bindings/mmc/arasan,sdhci.txt | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt > > index 3404afa..3b9f406 100644 > > --- a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt > > +++ b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt > > @@ -21,6 +21,10 @@ Required Properties: > > - interrupts: Interrupt specifier > > - interrupt-parent: Phandle for the interrupt controller that services > > interrupts for this device. > > +Optional Properties: > > +- fake-cd: On Zynq Devices the SDHCI Controller will not work without the cd > > + bit. When this option is set the driver will put the controller in test mode > > + and fake the cd bit so it will function. > > As Lars noted, the DT should describe the HW, and the policy of how to deal > with that should be left to the kernel. So from a DT perspective the above is > not correct. > > If I understand the linked documentation, this is slightly different to typical > uses of broken-cd in that in the absence of a card detect signal the HW will > not be able to access the SD card at all, even if requested to. Is that correct? > > If so, perhaps a better option is to have the combination of broken-cd and the > compatible string for this IP block imply that the test mode workaround is > required. Obviously that requires a fixup to the usual broken-cd binding to > remove the implication that polling alone must be used. > > Thanks, > Mark. In cases where the card is non-removable then polling doesn't make sense. So it doesn't make sense to tie the test mode workaround into the broken-cd property, even though I agree the nature of the defect fits under the notion of the CD being broken. -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
