Re: [Xen-devel] [PATCH v4 1/1] cameraif: add ABI for para-virtual camera

[Oleksandr Andrushchenko <andr2000@xxxxxxxxx>]

On 2/5/19 3:02 PM, Hans Verkuil wrote:
> On 2/5/19 1:30 PM, Oleksandr Andrushchenko wrote:
> > > Sorry for paying so much attention to this, but I think it is important that
> > > this is documented precisely.
> > Thank you for helping with this - your comments are really
> > important and make the description precise. Ok, so finally:
> >
> >   * num_bufs - uint8_t, desired number of buffers to be used.
> >   *
> >   * If num_bufs is not zero then the backend validates the requested number of
> >   * buffers and responds with the number of buffers allowed for this frontend.
> >   * Frontend is responsible for checking the corresponding response in order to
> >   * see if the values reported back by the backend do match the desired ones
> >   * and can be accepted.
> >   * Frontend is allowed to send multiple XENCAMERA_OP_BUF_REQUEST requests
> >   * before sending XENCAMERA_OP_STREAM_START request to update or tune the
> >   * final configuration.
> >   * Frontend is not allowed to change the number of buffers and/or camera
> >   * configuration after the streaming has started.
> >   *
> >   * If num_bufs is 0 and streaming has not started yet, then the backend may
> >   * free all previously allocated buffers (if any) or do nothing.
> I would rephrase this:
>
> * If num_bufs is 0 and streaming has not started yet, then the backend will
> * free all previously allocated buffers (if any).
>
> The previous text suggested that the backend might choose not to free
> the allocated buffers, but that's not the case.
Ok, makes sense
> >   * Trying to call this if streaming is in progress will result in an error.
> >   *
> >   * If camera reconfiguration is required then the streaming must be stopped
> >   * and this request must be sent with num_bufs set to zero and finally
> >   * buffers destroyed.
> >   *
> >   * Please note, that the number of buffers in this request must not exceed
> >   * the value configured in XenStore.max-buffers.
> >   *
> >   * See response format for this request.
> With that small change the text looks good to me.
Thank you for your time and help with this!
It seems I can push v5 for the (final?) review then
> Regards,
>
>         Hans
Thank you,
Oleksandr

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