Re: [Qemu-devel] [PATCH 4/8] bcm2835_emmc: add bcm2835 MMC/SD controller

[Kevin O'Connor <kevin@koconnor.net>]

On Wed, Dec 09, 2015 at 10:54:38AM -0800, Peter Crosthwaite wrote:
> On Wed, Dec 9, 2015 at 10:17 AM, Andrew Baumann
> <Andrew.Baumann@microsoft.com> wrote:
> >> From: Peter Crosthwaite [mailto:crosthwaitepeter@gmail.com]
> >> Sent: Tuesday, 8 December 2015 23:40
> >> On Tue, Dec 8, 2015 at 10:19 PM, Andrew Baumann
> >> <Andrew.Baumann@microsoft.com> wrote:
> >> >> From: Peter Crosthwaite [mailto:crosthwaitepeter@gmail.com]
> >> > I do not observe this behaviour on the real Pi2 (and it breaks UEFI). The
> >> hardware semantics appear to be "if the command generates a response,
> >> but you didn't want to see it, we'll successfully complete the command and
> >> ignore the response", whereas the sdhci implementation raises an error for
> >> this as well as signalling completion. I have read the "SD Specifications Part A2
> >> SD Host Controller Simplified Specification Version 2.00", but did not find
> >> anything describing this case, so it could be that this is open to interpretation.
> >> (It could also be specified in SDHC v3.) The specific error also seems odd -- my
> >> understanding is that a "command index" error means that the index in the
> >> response didn't match the index of the issued command, but that's hardly
> >> what is happening here.

FYI the SDHCI v3 spec is available online.  Confusingly, it's listed
as an addendum instead of explicitly as the sdhci spec.  The file is
partA2_300.pdf .

-Kevin