Messages in this thread | | | From | Mike Leach <> | Date | Thu, 6 Oct 2022 14:54:50 +0100 | Subject | Re: [PATCH v3 03/13] coresight: stm: Update STM driver to use Trace ID API |
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Hi Suzuki,
On Mon, 3 Oct 2022 at 10:04, Suzuki K Poulose <suzuki.poulose@arm.com> wrote: > > 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. >
coresight_trace_id_get_system_id() returns the ID if one can be allocated or -EINVAL if not.
Not sure what you are looking at here.
Mike
> Suzuki
-- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK
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