From: Hsin-Yi Wang <hsinyi@google.com>
To: Rex-BC Chen <rex-bc.chen@mediatek.com>
Cc: rafael@kernel.org, Viresh Kumar <viresh.kumar@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
krzk+dt@kernel.org, Matthias Brugger <matthias.bgg@gmail.com>,
Tim Chang <jia-wei.chang@mediatek.com>,
roger.lu@mediatek.com, Kevin Hilman <khilman@baylibre.com>,
angelogioacchino.delregno@collabora.com,
linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-mediatek@lists.infradead.org,
Project_Global_Chrome_Upstream_Group@mediatek.com
Subject: Re: [PATCH V3 10/15] cpufreq: mediatek: Add counter to prevent infinite loop when tracking voltage
Date: Fri, 15 Apr 2022 14:14:34 +0800 [thread overview]
Message-ID: <CACb=7PXykpUgZ+QG93Bd-vWstq2V-k6G0zTg+D1q2WchJHPbig@mail.gmail.com> (raw)
In-Reply-To: <20220415055916.28350-11-rex-bc.chen@mediatek.com>
On Fri, Apr 15, 2022 at 1:59 PM Rex-BC Chen <rex-bc.chen@mediatek.com> wrote:
>
> To prevent infinite loop when tracking voltage, we calculate the maximum
> value for each platform data.
> We assume min voltage is 0 and tracking target voltage using
> min_volt_shift for each iteration.
> The retry_max is 3 times of expeted iteration count.
>
> Signed-off-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
> ---
> drivers/cpufreq/mediatek-cpufreq.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
> index cc44a7a9427a..d4c00237e862 100644
> --- a/drivers/cpufreq/mediatek-cpufreq.c
> +++ b/drivers/cpufreq/mediatek-cpufreq.c
> @@ -86,6 +86,16 @@ static int mtk_cpufreq_voltage_tracking(struct mtk_cpu_dvfs_info *info,
> struct regulator *proc_reg = info->proc_reg;
> struct regulator *sram_reg = info->sram_reg;
> int pre_vproc, pre_vsram, new_vsram, vsram, vproc, ret;
> + int retry_max;
> +
> + /*
> + * We assume min voltage is 0 and tracking target voltage using
> + * min_volt_shift for each iteration.
> + * The retry_max is 3 times of expeted iteration count.
> + */
> + retry_max = 3 * DIV_ROUND_UP(max(info->soc_data->sram_max_volt,
> + info->soc_data->proc_max_volt),
> + info->soc_data->min_volt_shift);
mtk_cpufreq_voltage_tracking() will be called very frequently.
retry_max is the same every time mtk_cpufreq_voltage_tracking() is
called. Is it better to calculate before and store in
mtk_cpu_dvfs_info?
>
> pre_vproc = regulator_get_voltage(proc_reg);
> if (pre_vproc < 0) {
> @@ -151,6 +161,12 @@ static int mtk_cpufreq_voltage_tracking(struct mtk_cpu_dvfs_info *info,
>
> pre_vproc = vproc;
> pre_vsram = vsram;
> +
> + if (--retry_max < 0) {
> + dev_err(info->cpu_dev,
> + "over loop count, failed to set voltage\n");
> + return -EINVAL;
> + }
> } while (vproc != new_vproc || vsram != new_vsram);
>
> return 0;
> --
> 2.18.0
>
next prev parent reply other threads:[~2022-04-15 6:15 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-15 5:59 [PATCH V3 00/15] cpufreq: mediatek: Cleanup and support MT8183 and MT8186 Rex-BC Chen
2022-04-15 5:59 ` [PATCH V3 01/15] dt-bindings: cpufreq: mediatek: Add MediaTek CCI property Rex-BC Chen
2022-04-15 5:59 ` [PATCH V3 02/15] cpufreq: mediatek: Use device print to show logs Rex-BC Chen
2022-04-15 12:24 ` AngeloGioacchino Del Regno
2022-04-15 5:59 ` [PATCH V3 03/15] cpufreq: mediatek: Replace old_* with pre_* Rex-BC Chen
2022-04-15 12:24 ` AngeloGioacchino Del Regno
2022-04-15 5:59 ` [PATCH V3 04/15] cpufreq: mediatek: Record previous target vproc value Rex-BC Chen
2022-04-15 12:24 ` AngeloGioacchino Del Regno
2022-04-18 1:37 ` Rex-BC Chen
2022-04-15 5:59 ` [PATCH V3 06/15] cpufreq: mediatek: Move voltage limits to platform data Rex-BC Chen
2022-04-15 12:24 ` AngeloGioacchino Del Regno
2022-04-15 5:59 ` [PATCH V3 07/15] cpufreq: mediatek: Add .get function Rex-BC Chen
2022-04-15 5:59 ` [PATCH V3 08/15] cpufreq: mediatek: Make sram regulator optional Rex-BC Chen
2022-04-15 5:59 ` [PATCH V3 09/15] cpufreq: mediatek: Refine mtk_cpufreq_voltage_tracking() Rex-BC Chen
2022-04-15 5:59 ` [PATCH V3 10/15] cpufreq: mediatek: Add counter to prevent infinite loop when tracking voltage Rex-BC Chen
2022-04-15 6:14 ` Hsin-Yi Wang [this message]
2022-04-15 6:29 ` Rex-BC Chen
2022-04-15 12:24 ` AngeloGioacchino Del Regno
2022-04-18 1:40 ` Rex-BC Chen
2022-04-15 5:59 ` [PATCH V3 11/15] cpufreq: mediatek: Link CCI device to CPU Rex-BC Chen
2022-04-15 12:24 ` AngeloGioacchino Del Regno
2022-04-18 1:45 ` Rex-BC Chen
2022-04-20 18:09 ` Kevin Hilman
2022-04-15 5:59 ` [PATCH V3 12/15] cpufreq: mediatek: Add support for MT8186 Rex-BC Chen
2022-04-15 5:59 ` [PATCH V3 13/15] arm64: dts: mediatek: Add opp table and clock property for MT8183 cpufreq Rex-BC Chen
2022-04-15 12:24 ` AngeloGioacchino Del Regno
2022-04-18 1:46 ` Rex-BC Chen
2022-04-15 5:59 ` [PATCH V3 14/15] arm64: dts: mediatek: Add MediaTek CCI node for MT8183 Rex-BC Chen
2022-04-15 6:06 ` Hsin-Yi Wang
2022-04-15 6:10 ` Hsin-Yi Wang
2022-04-15 12:23 ` AngeloGioacchino Del Regno
2022-04-15 5:59 ` [PATCH V3 15/15] arm64: dts: mediatek: Add mediatek,cci property for MT8183 cpufreq Rex-BC Chen
2022-04-15 12:23 ` AngeloGioacchino Del Regno
[not found] ` <20220415055916.28350-6-rex-bc.chen@mediatek.com>
2022-04-15 12:24 ` [PATCH V3 05/15] cpufreq: mediatek: Add opp notification support AngeloGioacchino Del Regno
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