linux-kernel - Re: [PATCH V3 4/4] coresight: trbe: Enable ACPI based TRBE devices

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Message-ID: <f6a5aaf2-4669-cbc2-1358-e8cfb341b9c5@arm.com>
Date:   Mon, 7 Aug 2023 10:13:08 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-arm-kernel@...ts.infradead.org, suzuki.poulose@....com
Cc:     Sami Mujawar <sami.mujawar@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        James Clark <james.clark@....com>, coresight@...ts.linaro.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 4/4] coresight: trbe: Enable ACPI based TRBE devices



On 8/3/23 11:26, Anshuman Khandual wrote:
> This detects and enables ACPI based TRBE devices via the dummy platform
> device created earlier for this purpose.
> 
> Cc: Suzuki K Poulose <suzuki.poulose@....com>
> Cc: Mike Leach <mike.leach@...aro.org>
> Cc: Leo Yan <leo.yan@...aro.org>
> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Cc: coresight@...ts.linaro.org
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> ---
>  drivers/hwtracing/coresight/coresight-trbe.c | 9 +++++++++
>  drivers/hwtracing/coresight/coresight-trbe.h | 1 +
>  2 files changed, 10 insertions(+)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
> index e1d9d06e7725..f884883e9018 100644
> --- a/drivers/hwtracing/coresight/coresight-trbe.c
> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
> @@ -1537,7 +1537,16 @@ static const struct of_device_id arm_trbe_of_match[] = {
>  };
>  MODULE_DEVICE_TABLE(of, arm_trbe_of_match);
>  
> +#ifdef CONFIG_ACPI
> +static const struct platform_device_id arm_trbe_acpi_match[] = {
> +	{ ARMV8_TRBE_PDEV_NAME, 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(platform, arm_trbe_acpi_match);
> +#endif
> +
>  static struct platform_driver arm_trbe_driver = {
> +	.id_table = arm_trbe_acpi_match,

The build problem [1] reported on the first version of the series still exists
here i.e arm_trbe_acpi_match is hidden without CONFIG_ACPI. I had assumed that
CONFIG_CORESIGHT always enables CONFIG_ACPI, which is not the case. Following
random config (with CONFIG_ACPI=n and CONFIG_CORESIGHT_TRBE=y) easily triggers
the build problem.

https://download.01.org/0day-ci/archive/20230805/202308052123.uqR35d19-lkp@intel.com/config

 make CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 -s -j 128
drivers/hwtracing/coresight/coresight-trbe.c:1563:23: error: implicit declaration of function ‘ACPI_PTR’ [-Werror=implicit-function-declaration]
 1563 |   .acpi_match_table = ACPI_PTR(arm_trbe_acpi_match),
      |                       ^~~~~~~~
drivers/hwtracing/coresight/coresight-trbe.c:1563:32: error: ‘arm_trbe_acpi_match’ undeclared here (not in a function); did you mean ‘arm_trbe_of_match’?
 1563 |   .acpi_match_table = ACPI_PTR(arm_trbe_acpi_match),
      |                                ^~~~~~~~~~~~~~~~~~~
      |                                arm_trbe_of_match

Following config wrap around fixes the problem.

--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -1557,7 +1557,9 @@ MODULE_DEVICE_TABLE(platform, arm_trbe_acpi_match);
 #endif
 
 static struct platform_driver arm_trbe_driver = {
+#ifdef CONFIG_ACPI
        .id_table = arm_trbe_acpi_match,
+#endif
        .driver = {
                .name = DRVNAME,
                .of_match_table = of_match_ptr(arm_trbe_of_match),

Please not that unlike other coresight drivers, TRBE is not using 'acpi_device_id'
based "acpi_match_table = ACPI_PTR" construct. But regardless, ACPI_PTR() seems to
be an alternate (probably better) solution as well.

--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -1557,7 +1557,7 @@ MODULE_DEVICE_TABLE(platform, arm_trbe_acpi_match);
 #endif
 
 static struct platform_driver arm_trbe_driver = {
-       .id_table = arm_trbe_acpi_match,
+       .id_table = ACPI_PTR(arm_trbe_acpi_match),
        .driver = {
                .name = DRVNAME,
                .of_match_table = of_match_ptr(arm_trbe_of_match),
diff --git a/drivers/hwtracing/coresight/coresight-trbe.h b/drivers/hwtracing/coresight/coresight-trbe.h
index 94e67009848a..fce1735d5c58 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.h
+++ b/drivers/hwtracing/coresight/coresight-trbe.h
@@ -7,6 +7,7 @@
  *
  * Author: Anshuman Khandual <anshuman.khandual@....com>
  */
+#include <linux/acpi.h>
 #include <linux/coresight.h>
 #include <linux/device.h>
 #include <linux/irq.h>

[1] https://lore.kernel.org/all/202308052123.uqR35d19-lkp@intel.com/

>  	.driver	= {
>  		.name = DRVNAME,
>  		.of_match_table = of_match_ptr(arm_trbe_of_match),
> diff --git a/drivers/hwtracing/coresight/coresight-trbe.h b/drivers/hwtracing/coresight/coresight-trbe.h
> index 77cbb5c63878..94e67009848a 100644
> --- a/drivers/hwtracing/coresight/coresight-trbe.h
> +++ b/drivers/hwtracing/coresight/coresight-trbe.h
> @@ -12,6 +12,7 @@
>  #include <linux/irq.h>
>  #include <linux/kernel.h>
>  #include <linux/of.h>
> +#include <linux/perf/arm_pmu.h>
>  #include <linux/platform_device.h>
>  #include <linux/smp.h>
>