linux-kernel - Re: [PATCH 08/10] venus: vdec_ctrls: get real minimum buffers for capture

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Date:   Thu, 24 Jan 2019 17:43:28 +0900
From:   Alexandre Courbot <acourbot@...omium.org>
To:     Stanimir Varbanov <stanimir.varbanov@...aro.org>
Cc:     Linux Media Mailing List <linux-media@...r.kernel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil@...all.nl>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-arm-msm@...r.kernel.org,
        Vikash Garodia <vgarodia@...eaurora.org>,
        Tomasz Figa <tfiga@...omium.org>,
        Malathi Gottam <mgottam@...eaurora.org>
Subject: Re: [PATCH 08/10] venus: vdec_ctrls: get real minimum buffers for capture

On Fri, Jan 18, 2019 at 1:21 AM Stanimir Varbanov
<stanimir.varbanov@...aro.org> wrote:
>
> Until now we returned num_output_bufs set during reqbuf but
> that could be wrong when we implement stateful Codec API. So
> get the minimum buffers for capture from HFI. This is supposed
> to be called after stream header parsing, i.e. after dequeue
> v4l2 event for change resolution.
>
> Signed-off-by: Stanimir Varbanov <stanimir.varbanov@...aro.org>
> ---
>  drivers/media/platform/qcom/venus/vdec_ctrls.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/qcom/venus/vdec_ctrls.c b/drivers/media/platform/qcom/venus/vdec_ctrls.c
> index f4604b0cd57e..e1da87bf52bc 100644
> --- a/drivers/media/platform/qcom/venus/vdec_ctrls.c
> +++ b/drivers/media/platform/qcom/venus/vdec_ctrls.c
> @@ -16,6 +16,7 @@
>  #include <media/v4l2-ctrls.h>
>
>  #include "core.h"
> +#include "helpers.h"
>  #include "vdec.h"
>
>  static int vdec_op_s_ctrl(struct v4l2_ctrl *ctrl)
> @@ -47,7 +48,9 @@ static int vdec_op_g_volatile_ctrl(struct v4l2_ctrl *ctrl)
>  {
>         struct venus_inst *inst = ctrl_to_inst(ctrl);
>         struct vdec_controls *ctr = &inst->controls.dec;
> +       struct hfi_buffer_requirements bufreq;
>         union hfi_get_property hprop;
> +       enum hfi_version ver = inst->core->res->hfi_version;
>         u32 ptype = HFI_PROPERTY_PARAM_PROFILE_LEVEL_CURRENT;
>         int ret;
>
> @@ -71,7 +74,9 @@ static int vdec_op_g_volatile_ctrl(struct v4l2_ctrl *ctrl)
>                 ctrl->val = ctr->post_loop_deb_mode;
>                 break;
>         case V4L2_CID_MIN_BUFFERS_FOR_CAPTURE:
> -               ctrl->val = inst->num_output_bufs;
> +               ret = venus_helper_get_bufreq(inst, HFI_BUFFER_OUTPUT, &bufreq);
> +               if (!ret)
> +                       ctrl->val = HFI_BUFREQ_COUNT_MIN(&bufreq, ver);

What happens if venus_helper_get_bufreq() returns an error? It seems
that we just happily continue with whatever the previous value of
ctrl->val was. It seems like we do the same with other controls as
well.

I think you can fix this globally by initializing ret to 0 at the
beginning of the function, and then returning ret instead of 0 at the
end. That way all errors would be propagated. Of course please check
that this is relevant for other controls following this scheme before
doing so. :)