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:   Tue, 8 Feb 2022 15:08:55 +0800
From:   Yicong Yang <yangyicong@...wei.com>
To:     Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        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 2022/2/7 19:49, Jonathan Cameron wrote:
> 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>
> 

Thanks for the comments.

> 
>> ---
>>  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.
> 

yes. The valid data field is [0,15]. But
all 1 is used here to indicate that it's a
read process rather than a write process.

>> +
>> +	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.
> 

sure. will use field ops here and below.

Thanks.

>> +
>> +	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;
>> +}
>> +
> 
> 
> .
>