Re: [PATCH] hw/sd: sd: Bypass the RCA check for CMD13 in SPI mode

[Bin Meng]

Hi Philippe,

On Mon, Feb 8, 2021 at 9:08 PM Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
>
> On 1/30/21 11:20 AM, Bin Meng wrote:
> > Hi Philippe,
> >
> > On Fri, Jan 29, 2021 at 10:11 PM Philippe Mathieu-Daudé <f4bug@amsat.org> 
> > wrote:
> >>
> >> Hi Bin,
> >>
> >> On 1/29/21 9:51 AM, Bin Meng wrote:
> >>> From: Bin Meng <bin.meng@windriver.com>
> >>>
> >>> Unlike SD mode, when SD card is working in SPI mode, the argument
> >>> of CMD13 is stuff bits. Hence we should bypass the RCA check.
> >>
> >> Is this for detecting events by polling? From spec v8:
> >>
> >>   5.7.5 Event Indication Method
> >>   5.7.5.1 FX_EVENT (Bit06 of Card Status)
> >>
> >>     An event indication method is introduced from Version 4.20.
> >>     Card may use Bit06 of R1 (R1b) response of any SD command
> >>     to indicate event generation.
> >>
> >>   F.2 Concept of Event Detection Method
> >>   F.2.2 Host Implementation to use Event Detection Method
> >>
> >
> > I think you looked at the wrong place. See spec v8
> >
> > chapter 7.3.1.3 Detailed Command Description
> >
> > "The card shall ignore stuff bits and reserved bits in an argument"
> >
> > and Table 7-3 Commands and Arguments
> >
> > CMD13 Argument [31:0] stuff bits
>
> Indeed. Adding this information in the commit description makes
> things obvious ;)

I thought that's already obvious. If you search for "stuff bits" or
"CMD13" in the spec, you will get the information.

>
> The SPI responses are not well implemented, in this case (CMD13)
> it is incorrect, we should return a 2-byte R2. Your patch
> correctly skip the RCA check, but we still invalid data.

This is already handled in ssi-sd.c in SPI mode. As for the SD mode,
that should be a separate patch instead of mixing two fixes into one.

Regards,
Bin