Messages in this thread Patch in this message | | | Date | Thu, 15 Feb 2024 10:55:32 +0000 | Subject | Re: [PATCH V4 02/11] coresight: stm: Extract device name from AMBA pid based table lookup | From | Suzuki K Poulose <> |
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On 23/01/2024 05:45, Anshuman Khandual wrote: > Instead of using AMBA private data field, extract the device name from AMBA > pid based table lookup using new coresight_get_uci_data_from_amba() helper. > > Cc: Suzuki K Poulose <suzuki.poulose@arm.com> > Cc: Mike Leach <mike.leach@linaro.org> > Cc: James Clark <james.clark@arm.com> > Cc: coresight@lists.linaro.org > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Cc: linux-stm32@st-md-mailman.stormreply.com > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- > drivers/hwtracing/coresight/coresight-priv.h | 10 ++++++++++ > drivers/hwtracing/coresight/coresight-stm.c | 14 +++++++++++++- > 2 files changed, 23 insertions(+), 1 deletion(-) > > diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h > index 767076e07970..68cbb036cec8 100644 > --- a/drivers/hwtracing/coresight/coresight-priv.h > +++ b/drivers/hwtracing/coresight/coresight-priv.h > @@ -221,6 +221,16 @@ static inline void *coresight_get_uci_data(const struct amba_id *id) > return uci_id->data; > } > > +static inline void *coresight_get_uci_data_from_amba(const struct amba_id *table, u32 pid) > +{ > + while (table->mask) { > + if ((table->id & table->mask) == pid)
Why are we masking table->id ? table->id is a static value that the driver wants to check for "variants" of a given device. The table->mask is there to filter out the "irrelevant" bits of the PID that we read from the device. So this should instead be:
if ((table->mask & pid) == table->id)
> + return coresight_get_uci_data(table); > + table++; > + }; > + return NULL; > +} > + > void coresight_release_platform_data(struct coresight_device *csdev, > struct device *dev, > struct coresight_platform_data *pdata); > diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c > index a1c27c901ad1..9cdca4f86cab 100644 > --- a/drivers/hwtracing/coresight/coresight-stm.c > +++ b/drivers/hwtracing/coresight/coresight-stm.c > @@ -804,6 +804,18 @@ static void stm_init_generic_data(struct stm_drvdata *drvdata, > drvdata->stm.set_options = stm_generic_set_options; > } > > +#define STM_AMBA_MASK 0xfffff > + > +static const struct amba_id stm_ids[]; > + > +static char *stm_csdev_name(struct coresight_device *csdev) > +{ > + u32 stm_pid = coresight_get_pid(&csdev->access) & STM_AMBA_MASK;
Similar to above:
Why do we apply a "custom" mask to the PID and later check the PID with that of the table->pid.
The way it is supposed work is :
(table->mask & dev_pid) == table->pid
the table->mask is there for a reason: i.e., to get the relevant bits from the device_pid and compare it against "the" expected value (table->pid).
Suzuki
> + void *uci_data = coresight_get_uci_data_from_amba(stm_ids, stm_pid); > + > + return uci_data ? (char *)uci_data : "STM"; > +} > + > static int stm_probe(struct amba_device *adev, const struct amba_id *id) > { > int ret, trace_id; > @@ -900,7 +912,7 @@ static int stm_probe(struct amba_device *adev, const struct amba_id *id) > pm_runtime_put(&adev->dev); > > dev_info(&drvdata->csdev->dev, "%s initialized\n", > - (char *)coresight_get_uci_data(id)); > + stm_csdev_name(drvdata->csdev)); > return 0; > > cs_unregister:
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