RE: [PATCH V6 1/1] interconnect: intel: Add Keem Bay noc driver

["N, Pandith" <pandith.n@intel.com>]

Hi,

> -----Original Message-----
> From: Joe Perches <joe@perches.com>
> Sent: Tuesday, August 31, 2021 8:56 PM
> To: N, Pandith <pandith.n@intel.com>; georgi.djakov@linaro.org; linux-
> pm@vger.kernel.org; linux-kernel@vger.kernel.org
> Cc: mgross@linux.intel.com; Zhou, Furong <furong.zhou@intel.com>;
> Sangannavar, Mallikarjunappa <mallikarjunappa.sangannavar@intel.com>; Raja
> Subramanian, Lakshmi Bai <lakshmi.bai.raja.subramanian@intel.com>
> Subject: Re: [PATCH V6 1/1] interconnect: intel: Add Keem Bay noc driver
> 
> On Tue, 2021-08-31 at 12:06 +0530, pandith.n@intel.com wrote:
> > From: Pandith N <pandith.n@intel.com>
> >
> > Add support for Network on Chip(NOC) counters. Enable features to
> > configure and capture NOC probe counters, needed for DDR bandwidth
> > measurement. NOC driver is specific to Intel Keem Bay SOC. NOC
> > hardware counters are used for DDR statistics profiling, it is not related to
> timers.
> > Interface details are provided in include/uapi/linux/noc_uapi.h
> 
> trivial notes:
> 
> > diff --git a/drivers/interconnect/intel/Kconfig
> > b/drivers/interconnect/intel/Kconfig
> []
> > +config INTERCONNECT_INTEL_KEEMBAY
> > +	tristate "Intel Keem Bay Enable DDR profiling using NOC"
> > +	depends on INTERCONNECT_INTEL || ARCH_KEEMBAY ||
> COMPILE_TEST
> > +	help
> > +	  Enable this option for DDR bandwidth measurements using NOC
> > +
> > +	  Add support for Network-on-chip (NOC) in DDR Subsystem(DSS).
> > +	  DSS NOC has capabilities to enable and get statistics profiling.
> > +	  NOC driver enables features to configure and capture NOC probe
> > +          counters, needed for DSS bandwidth measurement.
> 
> Inconsistent tab/space indentation on this line
> 
It will corrected with tab + 2 spaces

> > diff --git a/drivers/interconnect/intel/keembay-bwmon.c
> > b/drivers/interconnect/intel/keembay-bwmon.c
> []
> > +/**
> > + * flex_noc_setup() - Setup two counters for the NOC probe
> > + * @noc: NOC type to setup counters
> > + * @counter: Counter number to set up counter n and n+1
> > + * @trace_port: trace port number to setup counters
> > + *
> > + * This function will setup the counters for the trace port given.
> 
> This seems to be unnecessary kernel-doc and if it is useful, the return value isn't
> described.
> 
Will add description for return value

> > +int flex_noc_setup(enum noc_ss_type noc, enum noc_counter counter,
> > +int trace_port) {
> > +	int offset;
> > +
> > +	if (noc >= NOC_TYPE_MAX || counter >= NOC_COUNTER_MAX)
> > +		return -EINVAL;
> > +
> > +	offset = f_offset[counter / 2];
> > +
> > +	/* Stop ongoing stats */
> > +	noc_writel(MAINCTL, 0);
> > +	noc_writel(CFGCTL, 0);
> > +
> > +	/* Setup trace port and counters port select */
> > +	noc_writel(TRACEPORTSEL, trace_port);
> > +	noc_writel((c_offset[counter] + C_PORTSEL), trace_port);
> 
> Lots of unnecessary parentheses
> 
Will change as below : 
noc_writel(c_offset[counter] + C_PORTSEL, trace_port);

> > +	noc_writel((c_offset[counter + 1] + C_PORTSEL), trace_port);
> > +
> > +	/* Setup counter sources & triggers, Alarm mode - OFF */
> > +	noc_writel((c_offset[counter] + C_SRC), COUNTERS_0_SRC_VAL);
> > +	noc_writel((c_offset[counter] + C_ALARMMODE),
> COUNTERS_ALARMMODE_VAL);
> > +	noc_writel((c_offset[counter + 1] + C_SRC), COUNTERS_1_SRC_VAL);
> > +	noc_writel((c_offset[counter + 1] + C_ALARMMODE),
> > +		   COUNTERS_ALARMMODE_VAL);
> 
> []
Will correct unnecessary parenthesis in above 4 statements
 
> 
> > +enum noc_status flexnoc_counter_capture(enum noc_ss_type noc,
> > +					enum noc_counter counter, u32
> *value) {
> > +	unsigned long j0, j1, delay;
> > +	u32 c0_0, c0_1;
> > +
> > +	if (noc >= NOC_TYPE_MAX ||
> > +	    counter >= NOC_COUNTER_MAX  ||
> > +	    !value)
> > +		return NOC_PROBE_ERR_INVALID_ARGS;
> > +
> > +	delay = msecs_to_jiffies(NOC_CAPTURE_TIMEOUT_MSEC);
> > +	j0 = jiffies;
> > +	j1 = j0 + delay;
> 
> j0 and j1 seem unnecessary
> 
Yes, will change it to single timeout variable.

> 	timeout = jiffies + msecs_to_jiffies(NOC_CAPTURE_TIMEOUT_MSEC);
> 
> > +	do {
> > +		c0_0 = noc_readl((c_offset[counter] + C_VAL));
> > +		usleep_range(10000, 11000);
> 
> Seems a long time.
> 
Will review if this time can be optimized.

> > +		c0_1 = noc_readl((c_offset[counter] + C_VAL));
> > +		/* If mainctrl is zero , return error */
> > +		if (noc_readl(MAINCTL) == 0)
> > +			return NOC_PROBE_ERR_IN_PROGRESS;
> > +		/* If counters are zero, keep reading */
> > +		if (0 == c0_0 && 0 == c0_1) {
> > +			break;
> > +		} else if (c0_0 != c0_1) {
> > +			continue;
> > +		} else {
> > +			/* counters look good break the while */
> > +			break;
> > +		}
> > +	} while (time_before(jiffies, j1));
> 
> 	} while (time_before(jiffies, timeout);
>
Variable will be renamed as timeout.
 
> []
> 
> > +static long noc_ioctl(struct file *file, unsigned int cmd, unsigned
> > +long arg) {
> > +	struct flexnoc_countercapture capture_data;
> > +	void __user *argp = (void __user *)arg;
> > +	struct flexnoc_probestart probe_data;
> > +	struct flexnoc_setup setup_data;
> > +	int rc;
> > +
> > +	if (!arg) {
> > +		pr_err("NOC: Null pointer from user\n");
> 
> Perhaps useful to add #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt near the
> top of the file.
> 
will add this line to the top of the file
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

Regards,
Pandith