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

[Bin Meng <bmeng.cn@gmail.com>]

On Mon, Feb 8, 2021 at 9:55 PM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> 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.

Sigh, I should have checked the spec before I replied.

The CMD13 response for SD card is R1. Only SPI mode is R2. As I
mentioned SPI mode R2 is already handled in ssi-sd.c, so there is
nothing wrong here.

Regards,
Bin