Re: [PATCH 2/3] m25p80: Improve command handling for Jedec and unsupported commands

[Cédric Le Goater]

On 2/3/20 7:09 PM, Guenter Roeck wrote:
> Always report 6 bytes of JEDEC data. Fill remaining data with 0.
> 
> For unsupported commands, keep sending a value of 0 until the chip
> is deselected.
> 
> Both changes avoid attempts to decode random commands. Up to now this
> happened if the reported Jedec data was shorter than 6 bytes but the
> host read 6 bytes, and with all unsupported commands.

Do you have a concrete example for that ? machine and flash model.

> Signed-off-by: Guenter Roeck <address@hidden>
> ---
>  hw/block/m25p80.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/block/m25p80.c b/hw/block/m25p80.c
> index 63e050d7d3..aca75edcc1 100644
> --- a/hw/block/m25p80.c
> +++ b/hw/block/m25p80.c
> @@ -1040,8 +1040,11 @@ static void decode_new_cmd(Flash *s, uint32_t value)
>          for (i = 0; i < s->pi->id_len; i++) {
>              s->data[i] = s->pi->id[i];
>          }
> +        for (; i < SPI_NOR_MAX_ID_LEN; i++) {
> +            s->data[i] = 0;
> +        }

It seems that data should be reseted in m25p80_cs() also.

>  
> -        s->len = s->pi->id_len;
> +        s->len = SPI_NOR_MAX_ID_LEN;
>          s->pos = 0;
>          s->state = STATE_READING_DATA;
>          break;
> @@ -1158,6 +1161,11 @@ static void decode_new_cmd(Flash *s, uint32_t value)
>          s->quad_enable = false;
>          break;
>      default:
> +        s->pos = 0;
> +        s->len = 1;
> +        s->state = STATE_READING_DATA;
> +        s->data_read_loop = true;
> +        s->data[0] = 0;
>          qemu_log_mask(LOG_GUEST_ERROR, "M25P80: Unknown cmd %x\n", value);
>          break;
>      }
>