Re: [Qemu-devel] [PATCH v2 04/14] sdcard: Extract sd_frame48/136_calc_checksum()

[Alistair Francis]

On Wed, May 9, 2018 at 5:16 PM, Philippe Mathieu-Daudé <address@hidden> wrote:
> On 05/09/2018 08:04 PM, Alistair Francis wrote:
>> On Wed, May 9, 2018 at 12:15 PM, Philippe Mathieu-Daudé <address@hidden> 
>> wrote:
>>> Hi Alistair,
>>>
>>> On 05/09/2018 03:00 PM, Alistair Francis wrote:
>>>> On Tue, May 8, 2018 at 8:46 PM, Philippe Mathieu-Daudé <address@hidden> 
>>>> wrote:
>>>>> It will help when moving this around for qtesting in the next commit.
>>>>>
>>>>> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
>>>>> ---
>>>>>  hw/sd/sd.c | 21 ++++++++++++++++++---
>>>>>  1 file changed, 18 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/hw/sd/sd.c b/hw/sd/sd.c
>>>>> index 27a70896cd..06607115a7 100644
>>>>> --- a/hw/sd/sd.c
>>>>> +++ b/hw/sd/sd.c
>>>>> @@ -273,6 +273,21 @@ static uint16_t sd_crc16(const void *message, size_t 
>>>>> width)
>>>>>      return shift_reg;
>>>>>  }
>>>>>
>>>>> +enum {
>>>>> +    F48_CONTENT_LENGTH  = 1 /* command */ + 4 /* argument */,
>>>>> +    F136_CONTENT_LENGTH = 15,
>>>>> +};
>>>>> +
>>>>> +static uint8_t sd_frame48_calc_checksum(const void *content)
>>>>> +{
>>>>> +    return sd_crc7(content, F48_CONTENT_LENGTH);
>>>>> +}
>>>>> +
>>>>> +static uint8_t sd_frame136_calc_checksum(const void *content)
>>>>> +{
>>>>> +    return (sd_crc7(content, F136_CONTENT_LENGTH) << 1) | 1;
>>>>> +}
>>>>> +
>>>>>  #define OCR_POWER_DELAY_NS      500000 /* 0.5ms */
>>>>>
>>>>>  FIELD(OCR, VDD_VOLTAGE_WINDOW,          0, 24)
>>>>> @@ -352,7 +367,7 @@ static void sd_set_cid(SDState *sd)
>>>>>      sd->cid[13] = 0x00 |       /* Manufacture date (MDT) */
>>>>>          ((MDT_YR - 2000) / 10);
>>>>>      sd->cid[14] = ((MDT_YR % 10) << 4) | MDT_MON;
>>>>> -    sd->cid[15] = (sd_crc7(sd->cid, 15) << 1) | 1;
>>>>> +    sd->cid[15] = sd_frame136_calc_checksum(sd->cid);
>>>>>  }
>>>>>
>>>>>  #define HWBLOCK_SHIFT  9                       /* 512 bytes */
>>>>> @@ -416,7 +431,7 @@ static void sd_set_csd(SDState *sd, uint64_t size)
>>>>>          sd->csd[13] = 0x40;
>>>>>          sd->csd[14] = 0x00;
>>>>>      }
>>>>> -    sd->csd[15] = (sd_crc7(sd->csd, 15) << 1) | 1;
>>>>> +    sd->csd[15] = sd_frame136_calc_checksum(sd->csd);
>>>>>  }
>>>>>
>>>>>  static void sd_set_rca(SDState *sd)
>>>>> @@ -491,7 +506,7 @@ static int sd_req_crc_validate(SDRequest *req)
>>>>>      buffer[0] = 0x40 | req->cmd;
>>>>>      stl_be_p(&buffer[1], req->arg);
>>>>>      return 0;
>>>>> -    return sd_crc7(buffer, 5) != req->crc;     /* TODO */
>>>>> +    return sd_frame48_calc_checksum(buffer) != req->crc; /* TODO */
>>>>
>>>> This 5 has changed to a 15. Is that on purpose? It should be mentioned
>>>> in the commit message if it is.
>>>
>>> I just extracted this function:
>>>
>>>   static uint8_t sd_frame48_calc_checksum(const void *content)
>>>   {
>>>       return sd_crc7(content, F48_CONTENT_LENGTH);
>>>   }
>>>
>>> Having:
>>>
>>>   enum {
>>>       F48_CONTENT_LENGTH  = 1 /* command */ + 4 /* argument */,
>>>
>>> So F48_CONTENT_LENGTH = 5 as previous.
>>
>> Ah, I missed the '+ 4 '. I just stopped reading at the comment.
>
> This way looked clearer to me, but it might not be...
> Would this be clearer?
>
>    F48_CONTENT_LENGTH  = 1 + 4 /* command + argument */,

I think this is clearer, but the way you have it now is fine as well.

>
>>
>> Looks good then:
>>
>> Reviewed-by: Alistair Francis <address@hidden>
>
> Thanks for your review time :)

No worries :)

Alistair

>
>>
>> Alistair
>>
>>>
>>> This function is later verified with tests from patch 12 of this series.
>>>
>>>>
>>>> Alistair
>>>>
>>>>>  }
>>>>>
>>>>>  static void sd_response_r1_make(SDState *sd, uint8_t *response)
>>>>> --
>>>>> 2.17.0
>>>>>
>>>>>