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Message-ID: <ae1d4e9a-6273-407e-952c-aec38e5c7a4f@quicinc.com>
Date: Tue, 19 Nov 2024 18:38:13 +0800
From: Jinlong Mao <quic_jinlmao@...cinc.com>
To: Suzuki K Poulose <suzuki.poulose@....com>,
Mike Leach
<mike.leach@...aro.org>, James Clark <james.clark@....com>,
Rob Herring
<robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley
<conor+dt@...nel.org>,
Alexander Shishkin
<alexander.shishkin@...ux.intel.com>
CC: <coresight@...ts.linaro.org>, <linux-arm-kernel@...ts.infradead.org>,
<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH v6 2/3] coresight: Add support to get static id for system
trace sources
On 2024/11/18 18:18, Suzuki K Poulose wrote:
> On 18/11/2024 10:14, Jinlong Mao wrote:
>>
>>
>> On 2024/11/13 21:27, Suzuki K Poulose wrote:
>>> On 04/11/2024 11:56, Mao Jinlong wrote:
>>>> Dynamic trace id was introduced in coresight subsystem, so trace id is
>>>> allocated dynamically. However, some hardware ATB source has static
>>>> trace
>>>> id and it cannot be changed via software programming. For such source,
>>>> it can call coresight_get_static_trace_id to get the fixed trace id
>>>> from
>>>> device node and pass id to coresight_trace_id_get_static_system_id to
>>>> reserve the id.
>>>>
>>>> Signed-off-by: Mao Jinlong <quic_jinlmao@...cinc.com>
>>>> Reviewed-by: Mike Leach <mike.leach@...aro.org>
>>>> ---
>>>> .../hwtracing/coresight/coresight-platform.c | 6 +++
>>>> .../hwtracing/coresight/coresight-trace-id.c | 39 ++++++++++++
>>>> +------
>>>> .../hwtracing/coresight/coresight-trace-id.h | 9 +++++
>>>> include/linux/coresight.h | 1 +
>>>> 4 files changed, 44 insertions(+), 11 deletions(-)
>>>>
>>>> diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/
>>>> drivers/hwtracing/coresight/coresight-platform.c
>>>> index 64e171eaad82..633d96b9577a 100644
>>>> --- a/drivers/hwtracing/coresight/coresight-platform.c
>>>> +++ b/drivers/hwtracing/coresight/coresight-platform.c
>>>> @@ -796,6 +796,12 @@ int coresight_get_cpu(struct device *dev)
>>>> }
>>>> EXPORT_SYMBOL_GPL(coresight_get_cpu);
>>>> +int coresight_get_static_trace_id(struct device *dev, u32 *id)
>>>> +{
>>>> + return fwnode_property_read_u32(dev_fwnode(dev), "arm,static-
>>>> trace-id", id);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(coresight_get_static_trace_id);
>>>> +
>>>> struct coresight_platform_data *
>>>> coresight_get_platform_data(struct device *dev)
>>>> {
>>>> diff --git a/drivers/hwtracing/coresight/coresight-trace-id.c b/
>>>> drivers/hwtracing/coresight/coresight-trace-id.c
>>>> index d98e12cb30ec..df8fe50b413f 100644
>>>> --- a/drivers/hwtracing/coresight/coresight-trace-id.c
>>>> +++ b/drivers/hwtracing/coresight/coresight-trace-id.c
>>>> @@ -12,6 +12,12 @@
>>>> #include "coresight-trace-id.h"
>>>> +enum trace_id_flags {
>>>> + TRACE_ID_ANY = 0x0,
>>>> + TRACE_ID_PREFER_ODD = 0x1,
>>>> + TRACE_ID_REQ_STATIC = 0x2,
>>>> +};
>>>> +
>>>> /* Default trace ID map. Used in sysfs mode and for system sources */
>>>> static DEFINE_PER_CPU(atomic_t, id_map_default_cpu_ids) =
>>>> ATOMIC_INIT(0);
>>>> static struct coresight_trace_id_map id_map_default = {
>>>> @@ -74,16 +80,18 @@ static int coresight_trace_id_find_odd_id(struct
>>>> coresight_trace_id_map *id_map)
>>>> * Otherwise allocate next available ID.
>>>> */
>>>> static int coresight_trace_id_alloc_new_id(struct
>>>> coresight_trace_id_map *id_map,
>>>> - int preferred_id, bool prefer_odd_id)
>>>> + int preferred_id, unsigned int flags)
>>>> {
>>>> int id = 0;
>>>> /* for backwards compatibility, cpu IDs may use preferred
>>>> value */
>>>> - if (IS_VALID_CS_TRACE_ID(preferred_id) &&
>>>> - !test_bit(preferred_id, id_map->used_ids)) {
>>>> - id = preferred_id;
>>>> - goto trace_id_allocated;
>>>> - } else if (prefer_odd_id) {
>>>> + if (IS_VALID_CS_TRACE_ID(preferred_id)) {
>>>> + if (!test_bit(preferred_id, id_map->used_ids)) {
>>>> + id = preferred_id;
>>>> + goto trace_id_allocated;
>>>> + } else if (flags & TRACE_ID_REQ_STATIC)
>>>> + return -EINVAL;
>>>
>>> nit: EBUSY sounds like a better choice here ? Requested ID is not
>>> available.
>>>
>>> Additionally, do we need to handle a case where the preferred_id is
>>> not valid ? I think we silently allocate a new trace id in such case ?
>>>
>>> Rest looks good to me.
>>>
>>> Suzuki
>>>
>>>
>>
>> If preferred_id is not valid, a random id will be allocated for the
>> source. For the normal source, 0 is provided here as preferred_id.
>
> My point is : If preferred_id is not valid *and* TRACE_ID_REQ_STATIC
> flag is set, we go ahead and allocate a random different ID. Which is
> not preferred. We should return -EINVAL in that case.
>
> Suzuki
>
>
Got your point. Thanks.
>>
>>>
>>>
>>>> + } else if (flags & TRACE_ID_PREFER_ODD) {
>>>> /* may use odd ids to avoid preferred legacy cpu IDs */
>>>> id = coresight_trace_id_find_odd_id(id_map);
>>>> if (id)
>>>> @@ -153,7 +161,7 @@ static int _coresight_trace_id_get_cpu_id(int
>>>> cpu, struct coresight_trace_id_map
>>>> */
>>>> id = coresight_trace_id_alloc_new_id(id_map,
>>>> CORESIGHT_LEGACY_CPU_TRACE_ID(cpu),
>>>> - false);
>>>> + TRACE_ID_ANY);
>>>> if (!IS_VALID_CS_TRACE_ID(id))
>>>> goto get_cpu_id_out_unlock;
>>>> @@ -188,14 +196,14 @@ static void _coresight_trace_id_put_cpu_id(int
>>>> cpu, struct coresight_trace_id_ma
>>>> DUMP_ID_MAP(id_map);
>>>> }
>>>> -static int coresight_trace_id_map_get_system_id(struct
>>>> coresight_trace_id_map *id_map)
>>>> +static int coresight_trace_id_map_get_system_id(struct
>>>> coresight_trace_id_map *id_map,
>>>> + int preferred_id, unsigned int traceid_flags)
>>>> {
>>>> unsigned long flags;
>>>> int id;
>>>> spin_lock_irqsave(&id_map->lock, flags);
>>>> - /* prefer odd IDs for system components to avoid legacy CPU IDS */
>>>> - id = coresight_trace_id_alloc_new_id(id_map, 0, true);
>>>> + id = coresight_trace_id_alloc_new_id(id_map, preferred_id,
>>>> traceid_flags);
>>>> spin_unlock_irqrestore(&id_map->lock, flags);
>>>> DUMP_ID(id);
>>>> @@ -255,10 +263,19 @@
>>>> EXPORT_SYMBOL_GPL(coresight_trace_id_read_cpu_id_map);
>>>> int coresight_trace_id_get_system_id(void)
>>>> {
>>>> - return coresight_trace_id_map_get_system_id(&id_map_default);
>>>> + /* prefer odd IDs for system components to avoid legacy CPU IDS */
>>>> + return coresight_trace_id_map_get_system_id(&id_map_default, 0,
>>>> + TRACE_ID_PREFER_ODD);
>>>> }
>>>> EXPORT_SYMBOL_GPL(coresight_trace_id_get_system_id);
>>>> +int coresight_trace_id_get_static_system_id(int trace_id)
>>>> +{
>>>> + return coresight_trace_id_map_get_system_id(&id_map_default,
>>>> + trace_id, TRACE_ID_REQ_STATIC);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(coresight_trace_id_get_static_system_id);
>>>> +
>>>> void coresight_trace_id_put_system_id(int id)
>>>> {
>>>> coresight_trace_id_map_put_system_id(&id_map_default, id);
>>>> diff --git a/drivers/hwtracing/coresight/coresight-trace-id.h b/
>>>> drivers/hwtracing/coresight/coresight-trace-id.h
>>>> index 9aae50a553ca..db68e1ec56b6 100644
>>>> --- a/drivers/hwtracing/coresight/coresight-trace-id.h
>>>> +++ b/drivers/hwtracing/coresight/coresight-trace-id.h
>>>> @@ -116,6 +116,15 @@ int coresight_trace_id_read_cpu_id_map(int cpu,
>>>> struct coresight_trace_id_map *i
>>>> */
>>>> int coresight_trace_id_get_system_id(void);
>>>> +/**
>>>> + * Allocate a CoreSight static trace ID for a system component.
>>>> + *
>>>> + * Used to allocate static IDs for system trace sources such as
>>>> dummy source.
>>>> + *
>>>> + * return: Trace ID or -EINVAL if allocation is impossible.
>>>> + */
>>>> +int coresight_trace_id_get_static_system_id(int id);
>>>> +
>>>> /**
>>>> * Release an allocated system trace ID.
>>>> *
>>>> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
>>>> index c13342594278..129795873072 100644
>>>> --- a/include/linux/coresight.h
>>>> +++ b/include/linux/coresight.h
>>>> @@ -662,6 +662,7 @@ void coresight_relaxed_write64(struct
>>>> coresight_device *csdev,
>>>> void coresight_write64(struct coresight_device *csdev, u64 val,
>>>> u32 offset);
>>>> extern int coresight_get_cpu(struct device *dev);
>>>> +extern int coresight_get_static_trace_id(struct device *dev, u32 *id);
>>>> struct coresight_platform_data *coresight_get_platform_data(struct
>>>> device *dev);
>>>> struct coresight_connection *
>>>
>>
>
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