On 16/05/2024 15:23, James Clark wrote: > > > On 16/05/2024 04:56, 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. Reserve trace id >> for this kind of hardware source. >> >> Signed-off-by: Mao Jinlong <quic_jinlmao@xxxxxxxxxxx> >> --- >> .../hwtracing/coresight/coresight-platform.c | 26 +++++++++++++++++++ >> .../hwtracing/coresight/coresight-trace-id.c | 24 +++++++++++++++++ >> .../hwtracing/coresight/coresight-trace-id.h | 11 ++++++++ >> include/linux/coresight.h | 1 + >> 4 files changed, 62 insertions(+) >> >> diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c >> index 9d550f5697fa..d3e22a2608df 100644 >> --- a/drivers/hwtracing/coresight/coresight-platform.c >> +++ b/drivers/hwtracing/coresight/coresight-platform.c >> @@ -183,6 +183,17 @@ static int of_coresight_get_cpu(struct device *dev) >> return cpu; >> } >> >> +/* >> + * of_coresight_get_trace_id: Get the atid of a source device. >> + * >> + * Returns 0 on success. >> + */ >> +static int of_coresight_get_trace_id(struct device *dev, u32 *id) >> +{ >> + >> + return of_property_read_u32(dev->of_node, "trace-id", id); >> +} >> + >> /* >> * of_coresight_parse_endpoint : Parse the given output endpoint @ep >> * and fill the connection information in @pdata->out_conns >> @@ -315,6 +326,12 @@ static inline int of_coresight_get_cpu(struct device *dev) >> { >> return -ENODEV; >> } >> + >> +static int of_coresight_get_trace_id(struct device *dev, u32 *id) >> +{ >> + return -ENODEV; >> +} >> + >> #endif >> >> #ifdef CONFIG_ACPI >> @@ -794,6 +811,15 @@ int coresight_get_cpu(struct device *dev) >> } >> EXPORT_SYMBOL_GPL(coresight_get_cpu); >> >> +int coresight_get_trace_id(struct device *dev, u32 *id) >> +{ >> + if (!is_of_node(dev->fwnode)) >> + return -EINVAL; >> + >> + return of_coresight_get_trace_id(dev, id); Can we somehow make this function name distinct from the trace ID functions. It's a bit hard to read that it's called coresight_get_trace_id() but it doesn't actually get an ID from the existing trace ID stuff. >> +} >> +EXPORT_SYMBOL_GPL(coresight_get_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 af5b4ef59cea..536a34e9de6f 100644 >> --- a/drivers/hwtracing/coresight/coresight-trace-id.c >> +++ b/drivers/hwtracing/coresight/coresight-trace-id.c >> @@ -110,6 +110,24 @@ static int coresight_trace_id_alloc_new_id(struct coresight_trace_id_map *id_map >> return id; >> } >> >> +static int coresight_trace_id_set(int id, struct coresight_trace_id_map *id_map) >> +{ >> + unsigned long flags; >> + >> + spin_lock_irqsave(&id_map_lock, flags); >> + >> + if (WARN(!IS_VALID_CS_TRACE_ID(id), "Invalid Trace ID %d\n", id)) >> + return -EINVAL; >> + if (WARN(test_bit(id, id_map->used_ids), "ID is already used: %d\n", id)) >> + return -EINVAL; > > Do these returns not skip unlocking the spinlock? > > It might be slightly fewer changes if we update the existing > coresight_trace_id_alloc_new_id() to add a new "only_preferred" option. > > Then use the existing system id allocator which already handles the lock > and unlock properly: > > static int coresight_trace_id_map_get_system_id(struct > coresight_trace_id_map *id_map, int id, > > bool only_preferred) > { > ... > 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, id, true, > only_preferred); > spin_unlock_irqrestore(&id_map_lock, flags); > ... > > I suppose the end result is the same as your implementation, but it > trades making one existing function slightly more complicated instead of > adding some new ones. It's also not that obvious that there is the new reserve function, but you still free the ID with the same coresight_trace_id_put_system_id(). Another benefit of adding arguments to the existing functions is that we keep just ...get...() and ...put...(). 'Reserve' implies some other new mechanism, but it's really a normal get. I think we should do one of these two options for the top level API: #1 (when id != 0, then it's an "only preferred" preferred ID: coresight_trace_id_get_system_id(int id) coresight_trace_id_put_system_id(int id) #2 coresight_trace_id_get_system_id() coresight_trace_id_get_system_id_resrv(int id) coresight_trace_id_put_system_id(int id)