Re: [Qemu-arm] [PATCH v2 2/9] hw/block/pflash_cfi01: Use the correct READ_ARRAY value

[John Snow]

On 7/1/19 8:12 PM, Philippe Mathieu-Daudé wrote:
> In the "Read Array Flowchart" the command has a value of 0xFF.
> 
> In the document [*] the "Read Array Flowchart", the READ_ARRAY
> command has a value of 0xff.
> 
> Use the correct value in the pflash model.
> 
> There is no change of behavior in the guest, because:
> - when the guest were sending 0xFF, the reset_flash label
>   was setting the command value as 0x00
> - 0x00 was used internally for READ_ARRAY
> 
> [*] "Common Flash Interface (CFI) and Command Sets"
>     (Intel Application Note 646)
>     Appendix B "Basic Command Set"
> 
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>

I'm assuming you tested a guest and saw it sending 0xFF; and based
entirely on the assumption that you tested this and it is not now worse:

Reviewed-by: John Snow <address@hidden>

> ---
>  hw/block/pflash_cfi01.c | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/block/pflash_cfi01.c b/hw/block/pflash_cfi01.c
> index dcc9885bf0..743b5d5794 100644
> --- a/hw/block/pflash_cfi01.c
> +++ b/hw/block/pflash_cfi01.c
> @@ -280,10 +280,9 @@ static uint32_t pflash_read(PFlashCFI01 *pfl, hwaddr 
> offset,
>          /* This should never happen : reset state & treat it as a read */
>          DPRINTF("%s: unknown command state: %x\n", __func__, pfl->cmd);
>          pfl->wcycle = 0;
> -        pfl->cmd = 0;
> +        pfl->cmd = 0xff;
>          /* fall through to read code */
> -    case 0x00:
> -        /* Flash area read */
> +    case 0xff: /* Read Array */
>          ret = pflash_data_read(pfl, offset, width, be);
>          break;
>      case 0x10: /* Single byte program */
> @@ -449,8 +448,6 @@ static void pflash_write(PFlashCFI01 *pfl, hwaddr offset,
>      case 0:
>          /* read mode */
>          switch (cmd) {
> -        case 0x00: /* ??? */
> -            goto reset_flash;
>          case 0x10: /* Single Byte Program */
>          case 0x40: /* Single Byte Program */
>              DPRINTF("%s: Single Byte Program\n", __func__);
> @@ -527,7 +524,7 @@ static void pflash_write(PFlashCFI01 *pfl, hwaddr offset,
>              if (cmd == 0xd0) { /* confirm */
>                  pfl->wcycle = 0;
>                  pfl->status |= 0x80;
> -            } else if (cmd == 0xff) { /* read array mode */
> +            } else if (cmd == 0xff) { /* Read Array */
>                  goto reset_flash;
>              } else
>                  goto error_flash;
> @@ -554,7 +551,7 @@ static void pflash_write(PFlashCFI01 *pfl, hwaddr offset,
>              } else if (cmd == 0x01) {
>                  pfl->wcycle = 0;
>                  pfl->status |= 0x80;
> -            } else if (cmd == 0xff) {
> +            } else if (cmd == 0xff) { /* read array mode */
>                  goto reset_flash;
>              } else {
>                  DPRINTF("%s: Unknown (un)locking command\n", __func__);
> @@ -646,7 +643,7 @@ static void pflash_write(PFlashCFI01 *pfl, hwaddr offset,
>      trace_pflash_reset();
>      memory_region_rom_device_set_romd(&pfl->mem, true);
>      pfl->wcycle = 0;
> -    pfl->cmd = 0;
> +    pfl->cmd = 0xff;
>  }
>  
>  
> @@ -762,7 +759,7 @@ static void pflash_cfi01_realize(DeviceState *dev, Error 
> **errp)
>      }
>  
>      pfl->wcycle = 0;
> -    pfl->cmd = 0;
> +    pfl->cmd = 0xff;
>      pfl->status = 0;
>      /* Hardcoded CFI table */
>      /* Standard "QRY" string */
> 

-- 
—js