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Message-ID: <CAPBb6MW-zxK+=HHUP5=+pO4Mswkhm=hDX7V56ABDm+BCzDaGHg@mail.gmail.com>
Date: Fri, 6 Mar 2020 16:50:25 +0900
From: Alexandre Courbot <acourbot@...omium.org>
To: Mansur Alisha Shaik <mansur@...eaurora.org>
Cc: Linux Media Mailing List <linux-media@...r.kernel.org>,
Stanimir Varbanov <stanimir.varbanov@...aro.org>,
LKML <linux-kernel@...r.kernel.org>,
linux-arm-msm@...r.kernel.org,
Vikash Garodia <vgarodia@...eaurora.org>
Subject: Re: [PATCH] venus: avoid extra locking in driver
On Fri, Mar 6, 2020 at 2:34 PM Mansur Alisha Shaik
<mansur@...eaurora.org> wrote:
>
> This change will avoid extra locking in driver.
Could you elaborate a bit more on the problem that this patch solves?
>
> Signed-off-by: Mansur Alisha Shaik <mansur@...eaurora.org>
> ---
> drivers/media/platform/qcom/venus/core.c | 2 +-
> drivers/media/platform/qcom/venus/core.h | 2 +-
> drivers/media/platform/qcom/venus/helpers.c | 11 +++++++++--
> drivers/media/platform/qcom/venus/pm_helpers.c | 8 ++++----
> 4 files changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/media/platform/qcom/venus/core.c b/drivers/media/platform/qcom/venus/core.c
> index 194b10b9..75d38b8 100644
> --- a/drivers/media/platform/qcom/venus/core.c
> +++ b/drivers/media/platform/qcom/venus/core.c
> @@ -447,7 +447,7 @@ static const struct freq_tbl sdm845_freq_table[] = {
> { 244800, 100000000 }, /* 1920x1080@30 */
> };
>
> -static struct codec_freq_data sdm845_codec_freq_data[] = {
> +static const struct codec_freq_data sdm845_codec_freq_data[] = {
> { V4L2_PIX_FMT_H264, VIDC_SESSION_TYPE_ENC, 675, 10 },
> { V4L2_PIX_FMT_HEVC, VIDC_SESSION_TYPE_ENC, 675, 10 },
> { V4L2_PIX_FMT_VP8, VIDC_SESSION_TYPE_ENC, 675, 10 },
> diff --git a/drivers/media/platform/qcom/venus/core.h b/drivers/media/platform/qcom/venus/core.h
> index ab7c360..8c8d0e9 100644
> --- a/drivers/media/platform/qcom/venus/core.h
> +++ b/drivers/media/platform/qcom/venus/core.h
> @@ -245,7 +245,7 @@ struct venus_buffer {
> struct clock_data {
> u32 core_id;
> unsigned long freq;
> - const struct codec_freq_data *codec_freq_data;
> + struct codec_freq_data codec_freq_data;
> };
>
> #define to_venus_buffer(ptr) container_of(ptr, struct venus_buffer, vb)
> diff --git a/drivers/media/platform/qcom/venus/helpers.c b/drivers/media/platform/qcom/venus/helpers.c
> index bcc6038..550c4ff 100644
> --- a/drivers/media/platform/qcom/venus/helpers.c
> +++ b/drivers/media/platform/qcom/venus/helpers.c
> @@ -807,6 +807,7 @@ int venus_helper_init_codec_freq_data(struct venus_inst *inst)
> unsigned int i, data_size;
> u32 pixfmt;
> int ret = 0;
> + bool found = false;
>
> if (!IS_V4(inst->core))
> return 0;
> @@ -816,16 +817,22 @@ int venus_helper_init_codec_freq_data(struct venus_inst *inst)
> pixfmt = inst->session_type == VIDC_SESSION_TYPE_DEC ?
> inst->fmt_out->pixfmt : inst->fmt_cap->pixfmt;
>
> + memset(&inst->clk_data.codec_freq_data, 0,
> + sizeof(inst->clk_data.codec_freq_data));
> +
> for (i = 0; i < data_size; i++) {
> if (data[i].pixfmt == pixfmt &&
> data[i].session_type == inst->session_type) {
> - inst->clk_data.codec_freq_data = &data[i];
> + inst->clk_data.codec_freq_data = data[i];
>From the patch I'd infer that inst->clk_data.codec_freq_data needs to
change at runtime. Is this what happens? Why? I'd expect that
frequency tables remain constant, and thus that the global
sdm845_codec_freq_data can remain constant while
clock_data::codec_freq_data is a const reference to it. What prevents
this from happening?
> + found = true;
> break;
> }
> }
>
> - if (!inst->clk_data.codec_freq_data)
> + if (!found) {
> + dev_err(inst->core->dev, "cannot find codec freq data\n");
> ret = -EINVAL;
> + }
>
> return ret;
> }
> diff --git a/drivers/media/platform/qcom/venus/pm_helpers.c b/drivers/media/platform/qcom/venus/pm_helpers.c
> index abf9315..240845e 100644
> --- a/drivers/media/platform/qcom/venus/pm_helpers.c
> +++ b/drivers/media/platform/qcom/venus/pm_helpers.c
> @@ -496,7 +496,7 @@ min_loaded_core(struct venus_inst *inst, u32 *min_coreid, u32 *min_load)
> list_for_each_entry(inst_pos, &core->instances, list) {
> if (inst_pos == inst)
> continue;
> - vpp_freq = inst_pos->clk_data.codec_freq_data->vpp_freq;
> + vpp_freq = inst_pos->clk_data.codec_freq_data.vpp_freq;
> coreid = inst_pos->clk_data.core_id;
>
> mbs_per_sec = load_per_instance(inst_pos);
> @@ -545,7 +545,7 @@ static int decide_core(struct venus_inst *inst)
> return 0;
>
> inst_load = load_per_instance(inst);
> - inst_load *= inst->clk_data.codec_freq_data->vpp_freq;
> + inst_load *= inst->clk_data.codec_freq_data.vpp_freq;
> max_freq = core->res->freq_tbl[0].freq;
>
> min_loaded_core(inst, &min_coreid, &min_load);
> @@ -848,10 +848,10 @@ static unsigned long calculate_inst_freq(struct venus_inst *inst,
>
> mbs_per_sec = load_per_instance(inst) / fps;
>
> - vpp_freq = mbs_per_sec * inst->clk_data.codec_freq_data->vpp_freq;
> + vpp_freq = mbs_per_sec * inst->clk_data.codec_freq_data.vpp_freq;
> /* 21 / 20 is overhead factor */
> vpp_freq += vpp_freq / 20;
> - vsp_freq = mbs_per_sec * inst->clk_data.codec_freq_data->vsp_freq;
> + vsp_freq = mbs_per_sec * inst->clk_data.codec_freq_data.vsp_freq;
>
> /* 10 / 7 is overhead factor */
> if (inst->session_type == VIDC_SESSION_TYPE_ENC)
> --
> 2.7.4
>
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