Re: [PATCH v2 08/13] hw/i2c/pmbus: Reset out buf after switching pages

[Titus Rwantare]

On Tue, 28 Jun 2022 at 20:36, Peter Delevoryas
<peterdelevoryas@gmail.com> wrote:
>
> When a pmbus device switches pages, it should clears its output buffer so
> that the next transaction doesn't emit data from the previous page.
>
> Fixes: 3746d5c15e70570b ("hw/i2c: add support for PMBus”)
> Signed-off-by: Peter Delevoryas <pdel@fb.com>
> ---
>  hw/i2c/pmbus_device.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/hw/i2c/pmbus_device.c b/hw/i2c/pmbus_device.c
> index 62885fa6a1..efddc36fd9 100644
> --- a/hw/i2c/pmbus_device.c
> +++ b/hw/i2c/pmbus_device.c
> @@ -1088,6 +1088,7 @@ static int pmbus_write_data(SMBusDevice *smd, uint8_t 
> *buf, uint8_t len)
>
>      if (pmdev->code == PMBUS_PAGE) {
>          pmdev->page = pmbus_receive8(pmdev);
> +        pmdev->out_buf_len = 0;
>          return 0;
>      }
>

I suspect you were running into this because ic_device_id was putting
too much data in the output buffer. Still, I wouldn't want the buffer
cleared if the page hasn't changed. Some drivers write the same page
before every read.

Titus