linux-kernel - RE: [EXT] Re: [PATCH 2/7] coresight: tmc-etr: Add support to use reserved trace memory

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Date:   Tue, 3 Oct 2023 04:34:36 +0000
From:   Linu Cherian <lcherian@...vell.com>
To:     James Clark <james.clark@....com>
CC:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "coresight@...ts.linaro.org" <coresight@...ts.linaro.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "conor+dt@...nel.org" <conor+dt@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Sunil Kovvuri Goutham <sgoutham@...vell.com>,
        George Cherian <gcherian@...vell.com>,
        Anil Kumar Reddy H <areddy3@...vell.com>,
        "suzuki.poulose@....com" <suzuki.poulose@....com>,
        "mike.leach@...aro.org" <mike.leach@...aro.org>,
        "leo.yan@...aro.org" <leo.yan@...aro.org>
Subject: RE: [EXT] Re: [PATCH 2/7] coresight: tmc-etr: Add support to use
 reserved trace memory

Hi James,

> -----Original Message-----
> From: James Clark <james.clark@....com>
> Sent: Monday, October 2, 2023 8:34 PM
> To: Linu Cherian <lcherian@...vell.com>
> Cc: linux-arm-kernel@...ts.infradead.org; coresight@...ts.linaro.org; linux-
> kernel@...r.kernel.org; robh+dt@...nel.org;
> krzysztof.kozlowski+dt@...aro.org; conor+dt@...nel.org;
> devicetree@...r.kernel.org; Sunil Kovvuri Goutham
> <sgoutham@...vell.com>; George Cherian <gcherian@...vell.com>; Anil
> Kumar Reddy H <areddy3@...vell.com>; suzuki.poulose@....com;
> mike.leach@...aro.org; leo.yan@...aro.org
> Subject: [EXT] Re: [PATCH 2/7] coresight: tmc-etr: Add support to use
> reserved trace memory
> 
> External Email
> 
> ----------------------------------------------------------------------
> 
> 
> On 29/09/2023 14:37, Linu Cherian wrote:
> > Add support to use reserved memory for coresight ETR trace buffer.
> >
> > Introduce a new ETR buffer mode called ETR_MODE_RESRV, which
> becomes
> > available when ETR device tree node is supplied with a valid reserved
> > memory region.
> >
> > ETR_MODE_RESRV can be selected only by explicit user request.
> >
> > $ echo resrv
> >/sys/bus/coresight/devices/tmc_etr<N>/buf_mode_preferred
> >
> > Signed-off-by: Anil Kumar Reddy <areddy3@...vell.com>
> > Signed-off-by: Linu Cherian <lcherian@...vell.com>
> > ---
> >  .../hwtracing/coresight/coresight-tmc-core.c  | 51 +++++++++++
> >  .../hwtracing/coresight/coresight-tmc-etr.c   | 87 ++++++++++++++++++-
> >  drivers/hwtracing/coresight/coresight-tmc.h   | 24 +++++
> >  3 files changed, 161 insertions(+), 1 deletion(-)
> 
> [...]
> 
> >
> > +static void tmc_get_reserved_region(struct device *parent) {
> > +	struct tmc_drvdata *drvdata = dev_get_drvdata(parent);
> > +	struct device_node *node;
> > +	struct resource res;
> > +	int rc;
> > +
> > +	node = tmc_get_region_byname(parent->of_node, "tracedata-
> mem");
> 
> Is this a typo? The DT commit says the region is called "trace-mem". And
> "metadata-mem" for the other region, but that one matches the other call to
> tmc_get_region_byname() added in the later commit.

Ack. Will fix in the next version.

> 
> > +	if (IS_ERR_OR_NULL(node)) {
> > +		dev_dbg(parent, "No reserved trace buffer specified\n");
> > +		goto out;
> > +	}
> > +