Re: [Qemu-arm] [PATCH 1/3] hw/i2c-ddc: Do not fail writes

[Peter Maydell]

On 17 February 2018 at 14:00, Linus Walleij <address@hidden> wrote:
> The tx function of the DDC I2C slave emulation was returning 1
> on all writes resulting in NACK in the I2C bus. Changing it to
> 0 makes the DDC I2C work fine with bit-banged I2C such as the
> versatile I2C.
>
> I guess it was not affecting whatever I2C controller this was
> used with until now, but with the Versatile I2C it surely
> does not work.
>
> Signed-off-by: Linus Walleij <address@hidden>
> ---
>  hw/i2c/i2c-ddc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/hw/i2c/i2c-ddc.c b/hw/i2c/i2c-ddc.c
> index 199dac9e41c1..bec0c91e2dd0 100644
> --- a/hw/i2c/i2c-ddc.c
> +++ b/hw/i2c/i2c-ddc.c
> @@ -259,12 +259,12 @@ static int i2c_ddc_tx(I2CSlave *i2c, uint8_t data)
>          s->reg = data;
>          s->firstbyte = false;
>          DPRINTF("[EDID] Written new pointer: %u\n", data);
> -        return 1;
> +        return 0;
>      }
>
>      /* Ignore all writes */
>      s->reg++;
> -    return 1;
> +    return 0;
>  }
>
>  static void i2c_ddc_init(Object *obj)
> --
> 2.14.3

Reviewed-by: Peter Maydell <address@hidden>

Does the guest attempting writes mean that we're missing functionality
that the hardware has? Is it interesting?

PS: I didn't see a cover letter email with this patchset --
if you can send a cover letter with multi-email patchsets that makes
our automated tooling much happier.

thanks
-- PMM