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

[Philippe Mathieu-Daudé]

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 ;)

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.