linux-kernel - Re: [PATCH v6 09/13] Add nodes for dsb edge control

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Message-ID: <2023062024-sincere-tripod-95dc@gregkh>
Date:   Tue, 20 Jun 2023 09:37:07 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Tao Zhang <quic_taozha@...cinc.com>
Cc:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Konrad Dybcio <konradybcio@...il.com>,
        Mike Leach <mike.leach@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Jinlong Mao <quic_jinlmao@...cinc.com>,
        Leo Yan <leo.yan@...aro.org>, coresight@...ts.linaro.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org,
        Tingwei Zhang <quic_tingweiz@...cinc.com>,
        Yuanfang Zhang <quic_yuanfang@...cinc.com>,
        Trilok Soni <quic_tsoni@...cinc.com>,
        Hao Zhang <quic_hazha@...cinc.com>,
        linux-arm-msm@...r.kernel.org, andersson@...nel.org
Subject: Re: [PATCH v6 09/13] Add nodes for dsb edge control

On Tue, Jun 20, 2023 at 03:32:37PM +0800, Tao Zhang wrote:
> Add the nodes to set value for DSB edge control and DSB edge
> control mask. Each DSB subunit TPDM has maximum of n(n<16) EDCR
> resgisters to configure edge control. DSB edge detection control
> 00: Rising edge detection
> 01: Falling edge detection
> 10: Rising and falling edge detection (toggle detection)
> And each DSB subunit TPDM has maximum of m(m<8) ECDMR registers to
> configure mask. Eight 32 bit registers providing DSB interface
> edge detection mask control.
> 
> Signed-off-by: Tao Zhang <quic_taozha@...cinc.com>
> ---
>  .../ABI/testing/sysfs-bus-coresight-devices-tpdm   |  32 +++++
>  drivers/hwtracing/coresight/coresight-tpdm.c       | 143 ++++++++++++++++++++-
>  drivers/hwtracing/coresight/coresight-tpdm.h       |  22 ++++
>  3 files changed, 196 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> index 2a82cd0..34189e4a 100644
> --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> @@ -60,3 +60,35 @@ Description:
>  		Bit[3] : Set to 0 for low performance mode.
>  				 Set to 1 for high performance mode.
>  		Bit[4:8] : Select byte lane for high performance mode.
> +
> +What:		/sys/bus/coresight/devices/<tpdm-name>/dsb_edge_ctrl
> +Date:		March 2023
> +KernelVersion	6.5
> +Contact:	Jinlong Mao (QUIC) <quic_jinlmao@...cinc.com>, Tao Zhang (QUIC) <quic_taozha@...cinc.com>
> +Description:
> +		Read/Write a set of the edge control registers of the DSB
> +		in TPDM.
> +
> +		Expected format is the following:
> +		<integer1> <integer2> <integer3>

sysfs is "one value", not 3.  Please never have to parse a sysfs file.

> +static ssize_t dsb_edge_ctrl_show(struct device *dev,
> +				       struct device_attribute *attr,
> +				       char *buf)
> +{
> +	struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> +	ssize_t size = 0;
> +	unsigned long bytes;
> +	int i;
> +
> +	spin_lock(&drvdata->spinlock);
> +	for (i = 0; i < TPDM_DSB_MAX_EDCR; i++) {
> +		bytes = sysfs_emit_at(buf, size,
> +				  "Index:0x%x Val:0x%x\n", i,

Again, no, one value, no "string" needed to parse anything.

greg k-h