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SubjectRe: [PATCH 2/3] venus: Limit HFI sessions to the maximum supported
On Sun, Nov 22, 2020 at 6:48 AM Stanimir Varbanov
<stanimir.varbanov@linaro.org> wrote:
>
>
>
> On 11/21/20 3:14 AM, Fritz Koenig wrote:
> > On Thu, Nov 19, 2020 at 4:12 PM Stanimir Varbanov
> > <stanimir.varbanov@linaro.org> wrote:
> >>
> >> Currently we rely on firmware to return error when we reach the maximum
> >> supported number of sessions. But this errors are happened at reqbuf
> >> time which is a bit later. The more reasonable way looks like is to
> >> return the error on driver open.
> >>
> >> To achieve that modify hfi_session_create to return error when we reach
> >> maximum count of sessions and thus refuse open.
> >>
> >> Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
> >> ---
> >> drivers/media/platform/qcom/venus/core.h | 1 +
> >> drivers/media/platform/qcom/venus/hfi.c | 19 +++++++++++++++----
> >> .../media/platform/qcom/venus/hfi_parser.c | 3 +++
> >> 3 files changed, 19 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/media/platform/qcom/venus/core.h b/drivers/media/platform/qcom/venus/core.h
> >> index db0e6738281e..3a477fcdd3a8 100644
> >> --- a/drivers/media/platform/qcom/venus/core.h
> >> +++ b/drivers/media/platform/qcom/venus/core.h
> >> @@ -96,6 +96,7 @@ struct venus_format {
> >> #define MAX_CAP_ENTRIES 32
> >> #define MAX_ALLOC_MODE_ENTRIES 16
> >> #define MAX_CODEC_NUM 32
> >> +#define MAX_SESSIONS 16
> >>
> >> struct raw_formats {
> >> u32 buftype;
> >> diff --git a/drivers/media/platform/qcom/venus/hfi.c b/drivers/media/platform/qcom/venus/hfi.c
> >> index 638ed5cfe05e..8420be6d3991 100644
> >> --- a/drivers/media/platform/qcom/venus/hfi.c
> >> +++ b/drivers/media/platform/qcom/venus/hfi.c
> >> @@ -175,6 +175,7 @@ static int wait_session_msg(struct venus_inst *inst)
> >> int hfi_session_create(struct venus_inst *inst, const struct hfi_inst_ops *ops)
> >> {
> >> struct venus_core *core = inst->core;
> >> + int ret;
> >>
> >> if (!ops)
> >> return -EINVAL;
> >> @@ -183,12 +184,22 @@ int hfi_session_create(struct venus_inst *inst, const struct hfi_inst_ops *ops)
> >> init_completion(&inst->done);
> >> inst->ops = ops;
> >>
> >> - mutex_lock(&core->lock);
> >> - list_add_tail(&inst->list, &core->instances);
> >> - atomic_inc(&core->insts_count);
> >> + ret = mutex_lock_interruptible(&core->lock);
> >> + if (ret)
> >> + return ret;
> >> +
> >> + ret = atomic_read(&core->insts_count);
> >> + if (ret + 1 > core->max_sessions_supported) {
> >> + ret = -EAGAIN;
> >> + } else {
> >> + atomic_inc(&core->insts_count);
> >> + list_add_tail(&inst->list, &core->instances);
> >> + ret = 0;
> >> + }
> >> +
> >> mutex_unlock(&core->lock);
> >>
> >> - return 0;
> >> + return ret;
> >> }
> >> EXPORT_SYMBOL_GPL(hfi_session_create);
> >>
> >> diff --git a/drivers/media/platform/qcom/venus/hfi_parser.c b/drivers/media/platform/qcom/venus/hfi_parser.c
> >> index 363ee2a65453..52898633a8e6 100644
> >> --- a/drivers/media/platform/qcom/venus/hfi_parser.c
> >> +++ b/drivers/media/platform/qcom/venus/hfi_parser.c
> >> @@ -276,6 +276,9 @@ u32 hfi_parser(struct venus_core *core, struct venus_inst *inst, void *buf,
> >> words_count--;
> >> }
> >>
> >
> > My understanding of the hardware is that there is a max number of
> > macroblocks that can be worked on at a time. That works out to
> > nominally 16 clips. But large clips can take more resources. Does
> > |max_sessions_supported| get updated with the amount that system can
> > use? Or is it always a constant?
>
> The number of max sessions supported is constant.
>
> >
> > If it changes depending on system load, then couldn't
> > be 0 if all of the resources have been
> > used up? If that is the case then the below check would appear to be
> > incorrect.
>
> No, this is not the case. Changing dynamically the number of max
> sessions depending on session load is possible but it would be complex
> to implement. For example, think of decoder dynamic resolution change
> where we don't know in advance the new resolution (session load).
>

Sorry, I should have been more specific. The complexity of
dynamically changing the max sessions did not seem to be captured in
the patch, so I wanted to make sure that
|core->max_sessions_supported| was constant. As it is constant, then
this patch looks to capture everything.

Reviewed-by: Fritz Koenig <frkoenig@chromium.org>
> >
> >> + if (!core->max_sessions_supported)
> >> + core->max_sessions_supported = MAX_SESSIONS;
> >> +
> >> parser_fini(inst, codecs, domain);
> >>
> >> return HFI_ERR_NONE;
> >> --
> >> 2.17.1
> >>
>
> --
> regards,
> Stan

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