Messages in this thread | | | Date | Mon, 3 Oct 2022 10:04:19 +0100 | Subject | Re: [PATCH v3 03/13] coresight: stm: Update STM driver to use Trace ID API | From | Suzuki K Poulose <> |
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On 09/08/2022 23:33, Mike Leach wrote: > Updates the STM driver to use the trace ID allocation API. > This uses the _system_id calls to allocate an ID on device poll, > and release on device remove. > > The sysfs access to the STMTRACEIDR register has been changed from RW > to RO. Having this value as writable is not appropriate for the new > Trace ID scheme - and had potential to cause errors in the previous > scheme if values clashed with other sources. > > Signed-off-by: Mike Leach <mike.leach@linaro.org> > Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> > --- > drivers/hwtracing/coresight/coresight-stm.c | 41 +++++++-------------- > 1 file changed, 14 insertions(+), 27 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c > index bb14a3a8a921..9ef3e923a930 100644 > --- a/drivers/hwtracing/coresight/coresight-stm.c > +++ b/drivers/hwtracing/coresight/coresight-stm.c > @@ -31,6 +31,7 @@ > #include <linux/stm.h> > > #include "coresight-priv.h" > +#include "coresight-trace-id.h" > > #define STMDMASTARTR 0xc04 > #define STMDMASTOPR 0xc08 > @@ -615,24 +616,7 @@ static ssize_t traceid_show(struct device *dev, > val = drvdata->traceid; > return sprintf(buf, "%#lx\n", val); > } > - > -static ssize_t traceid_store(struct device *dev, > - struct device_attribute *attr, > - const char *buf, size_t size) > -{ > - int ret; > - unsigned long val; > - struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent); > - > - ret = kstrtoul(buf, 16, &val); > - if (ret) > - return ret; > - > - /* traceid field is 7bit wide on STM32 */ > - drvdata->traceid = val & 0x7f; > - return size; > -} > -static DEVICE_ATTR_RW(traceid); > +static DEVICE_ATTR_RO(traceid); > > #define coresight_stm_reg(name, offset) \ > coresight_simple_reg32(struct stm_drvdata, name, offset) > @@ -819,14 +803,6 @@ static void stm_init_default_data(struct stm_drvdata *drvdata) > */ > drvdata->stmsper = ~0x0; > > - /* > - * The trace ID value for *ETM* tracers start at CPU_ID * 2 + 0x10 and > - * anything equal to or higher than 0x70 is reserved. Since 0x00 is > - * also reserved the STM trace ID needs to be higher than 0x00 and > - * lowner than 0x10. > - */ > - drvdata->traceid = 0x1; > - > /* Set invariant transaction timing on all channels */ > bitmap_clear(drvdata->chs.guaranteed, 0, drvdata->numsp); > } > @@ -854,7 +830,7 @@ static void stm_init_generic_data(struct stm_drvdata *drvdata, > > static int stm_probe(struct amba_device *adev, const struct amba_id *id) > { > - int ret; > + int ret, trace_id; > void __iomem *base; > struct device *dev = &adev->dev; > struct coresight_platform_data *pdata = NULL; > @@ -938,12 +914,22 @@ static int stm_probe(struct amba_device *adev, const struct amba_id *id) > goto stm_unregister; > } > > + trace_id = coresight_trace_id_get_system_id(); > + if (trace_id < 0) {
The above API returns "INVALID_ID" and not a negative error status. I think it is better to fix the API to return:
ret < 0 - If there is any error - Otherwise a positive integer And the users should be kept unaware of which ID is valid or invalid.
Suzuki
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