[OpenBIOS] [PATCH 3/5] ppc: fix CUDA ADB packet header format

[Mark Cave-Ayland]

On 09/10/15 17:20, Mark Cave-Ayland wrote:

> From: Cormac O'Brien <cormac at c-obrien.org>
> 
> QEMU <= 2.4 uses a 2-byte header for CUDA ADB packets where it should use a
> 3-byte one, so this commit allows cuda_adb_req() to differentiate between the
> two formats and act accordingly.
> 
> Signed-off-by: Cormac O'Brien <cormac at c-obrien.org>
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland at ilande.co.uk>
> ---
>  openbios-devel/drivers/cuda.c |   14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/openbios-devel/drivers/cuda.c b/openbios-devel/drivers/cuda.c
> index f117b0b..836380f 100644
> --- a/openbios-devel/drivers/cuda.c
> +++ b/openbios-devel/drivers/cuda.c
> @@ -144,8 +144,18 @@ static int cuda_adb_req (void *host, const uint8_t *snd_buf, int len,
>   //   CUDA_DPRINTF("len: %d %02x\n", len, snd_buf[0]);
>      len = cuda_request(host, ADB_PACKET, snd_buf, len, buffer);
>      if (len > 1 && buffer[0] == ADB_PACKET) {
> -        pos = buffer + 2;
> -        len -= 2;
> +        /* QEMU <= 2.4 uses a 2-byte header where it should use a 3-byte one,
> +         * so we check to see what kind of header we ought to use.
> +         */
> +        if (len > 2 && buffer[2] == snd_buf[0]) {
> +            /* Correct 3-byte header */
> +            pos = buffer + 3;
> +            len -= 3;
> +        } else {
> +            /* Old 2-byte header */
> +            pos = buffer + 2;
> +            len -= 2;
> +        }
>      } else {
>          pos = buffer + 1;
>          len = -1;
> 

For the record this patch is actually correct, however after some
further testing with QEMU the comment is wrong - it's only ADB *error*
packets which have a 3 byte header, whilst normal packets still have a 2
byte header.

Other than that the patchset passes all my tests here, so I'll commit it
shortly in preparation for sending a QEMU pull request.


ATB,

Mark.