linux-kernel - Re: [PATCH v3 4/8] hisi_ptt: Add tune function support for HiSilicon PCIe Tune and Trace device

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Date:   Mon, 7 Feb 2022 11:49:11 +0000
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Yicong Yang <yangyicong@...ilicon.com>
CC:     <gregkh@...uxfoundation.org>, <helgaas@...nel.org>,
        <alexander.shishkin@...ux.intel.com>, <lorenzo.pieralisi@....com>,
        <will@...nel.org>, <mark.rutland@....com>,
        <mathieu.poirier@...aro.org>, <suzuki.poulose@....com>,
        <mike.leach@...aro.org>, <leo.yan@...aro.org>,
        <daniel.thompson@...aro.org>, <joro@...tes.org>,
        <john.garry@...wei.com>, <shameerali.kolothum.thodi@...wei.com>,
        <robin.murphy@....com>, <peterz@...radead.org>, <mingo@...hat.com>,
        <acme@...nel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <coresight@...ts.linaro.org>, <linux-pci@...r.kernel.org>,
        <linux-perf-users@...r.kernel.org>,
        <iommu@...ts.linux-foundation.org>, <prime.zeng@...wei.com>,
        <liuqi115@...wei.com>, <zhangshaokun@...ilicon.com>,
        <linuxarm@...wei.com>, <song.bao.hua@...ilicon.com>
Subject: Re: [PATCH v3 4/8] hisi_ptt: Add tune function support for
 HiSilicon PCIe Tune and Trace device

On Mon, 24 Jan 2022 21:11:14 +0800
Yicong Yang <yangyicong@...ilicon.com> wrote:

> Add tune function for the HiSilicon Tune and Trace device. The interface
> of tune is exposed through sysfs attributes of PTT PMU device.
> 
> Signed-off-by: Yicong Yang <yangyicong@...ilicon.com>

A few trivial things inline, but looks good in general to me.
With those tidied up
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>


> ---
>  drivers/hwtracing/ptt/hisi_ptt.c | 154 +++++++++++++++++++++++++++++++
>  drivers/hwtracing/ptt/hisi_ptt.h |  19 ++++
>  2 files changed, 173 insertions(+)
> 
> diff --git a/drivers/hwtracing/ptt/hisi_ptt.c b/drivers/hwtracing/ptt/hisi_ptt.c
> index 2994354e690b..b11e702eb506 100644
> --- a/drivers/hwtracing/ptt/hisi_ptt.c
> +++ b/drivers/hwtracing/ptt/hisi_ptt.c
> @@ -21,6 +21,159 @@
>  
>  #include "hisi_ptt.h"
>  
> +static int hisi_ptt_wait_tuning_finish(struct hisi_ptt *hisi_ptt)
> +{
> +	u32 val;
> +
> +	return readl_poll_timeout(hisi_ptt->iobase + HISI_PTT_TUNING_INT_STAT,
> +				  val, !(val & HISI_PTT_TUNING_INT_STAT_MASK),
> +				  HISI_PTT_WAIT_POLL_INTERVAL_US,
> +				  HISI_PTT_WAIT_TIMEOUT_US);
> +}
> +
> +static int hisi_ptt_tune_data_get(struct hisi_ptt *hisi_ptt,
> +				  u32 event, u16 *data)
> +{
> +	u32 reg;
> +
> +	reg = readl(hisi_ptt->iobase + HISI_PTT_TUNING_CTRL);
> +	reg &= ~(HISI_PTT_TUNING_CTRL_CODE | HISI_PTT_TUNING_CTRL_SUB);
> +	reg |= FIELD_PREP(HISI_PTT_TUNING_CTRL_CODE | HISI_PTT_TUNING_CTRL_SUB,
> +			  event);
> +	writel(reg, hisi_ptt->iobase + HISI_PTT_TUNING_CTRL);
> +
> +	/* Write all 1 to indicates it's the read process */
> +	writel(~0UL, hisi_ptt->iobase + HISI_PTT_TUNING_DATA);

Just to check, this is includes the bits above the DATA_VAL_MASK?
Fine if so, just seems odd to define a field but then write 
parts of the register that aren't part of that field.

> +
> +	if (hisi_ptt_wait_tuning_finish(hisi_ptt))
> +		return -ETIMEDOUT;
> +
> +	reg = readl(hisi_ptt->iobase + HISI_PTT_TUNING_DATA);
> +	reg &= HISI_PTT_TUNING_DATA_VAL_MASK;
> +	*data = (u16)reg;

As below, prefer a FIELD_GET() for this.

> +
> +	return 0;
> +}
> +
> +static int hisi_ptt_tune_data_set(struct hisi_ptt *hisi_ptt,
> +				  u32 event, u16 data)
> +{
> +	u32 reg;
> +
> +	reg = readl(hisi_ptt->iobase + HISI_PTT_TUNING_CTRL);
> +	reg &= ~(HISI_PTT_TUNING_CTRL_CODE | HISI_PTT_TUNING_CTRL_SUB);
> +	reg |= FIELD_PREP(HISI_PTT_TUNING_CTRL_CODE | HISI_PTT_TUNING_CTRL_SUB,
> +			  event);
> +	writel(reg, hisi_ptt->iobase + HISI_PTT_TUNING_CTRL);
> +
> +	reg = data;
Given you defined HISI_PTT_TUNING_DATA_VAL_MASK why not use it here

writel(FIELD_PREP(..), ...)? 

> +	writel(reg, hisi_ptt->iobase + HISI_PTT_TUNING_DATA);
> +
> +	if (hisi_ptt_wait_tuning_finish(hisi_ptt))
> +		return -ETIMEDOUT;
> +
> +	return 0;
> +}
> +