Re: [PATCH 08/17] coresight: tmc: Add configuration support for trace buffer size

On Thu, Oct 19, 2017 at 06:15:44PM +0100, Suzuki K Poulose wrote:

Now that we can dynamically switch between contiguous memory and SG table depending on the trace buffer size, provide the support for selecting an appropriate buffer size.

Cc: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com

---

.../ABI/testing/sysfs-bus-coresight-devices-tmc | 8 ++++++ drivers/hwtracing/coresight/coresight-tmc.c | 32 ++++++++++++++++++++++ 2 files changed, 40 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tmc b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tmc index 4fe677ed1305..3675c380caf8 100644 --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tmc +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tmc @@ -83,3 +83,11 @@ KernelVersion: 4.7 Contact: Mathieu Poirier mathieu.poirier@linaro.org Description: (R) Indicates the capabilities of the Coresight TMC. The value is read directly from the DEVID register, 0xFC8,

+What: /sys/bus/coresight/devices/<memory_map>.tmc/buffer-size +Date: September 2017 +KernelVersion: 4.15

More like 4.16 now.

+Contact: Mathieu Poirier mathieu.poirier@linaro.org +Description: (RW) Size of the trace buffer for TMC-ETR when used in SYSFS

• mode. Writable only for TMC-ETR configurations. The value
  

• should be aligned to the kernel pagesize.
  

diff --git a/drivers/hwtracing/coresight/coresight-tmc.c b/drivers/hwtracing/coresight/coresight-tmc.c index c7201e40d737..2349b1805694 100644 --- a/drivers/hwtracing/coresight/coresight-tmc.c +++ b/drivers/hwtracing/coresight/coresight-tmc.c @@ -283,8 +283,40 @@ static ssize_t trigger_cntr_store(struct device *dev, } static DEVICE_ATTR_RW(trigger_cntr); +static ssize_t buffer_size_show(struct device *dev,

• 		struct device_attribute *attr, char *buf)
  

+{

• struct tmc_drvdata *drvdata = dev_get_drvdata(dev->parent);
• return sprintf(buf, "%#x\n", drvdata->size);

+}

+static ssize_t buffer_size_store(struct device *dev,

• 	     struct device_attribute *attr,
  

• 	     const char *buf, size_t size)
  

Indentation (I know trigger_cntr_store() is wrong).

+{

• int ret;
• unsigned long val;
• struct tmc_drvdata *drvdata = dev_get_drvdata(dev->parent);
• if (drvdata->config_type != TMC_CONFIG_TYPE_ETR)

• return -EPERM;
  

I think -EINVAL would be more appropriate but definitely not a big deal.

• ret = kstrtoul(buf, 0, &val);
• if (ret)

• return ret;
  

• /* The buffer size should be page aligned */
• if (val & (PAGE_SIZE - 1))

• return -EINVAL;
  

• drvdata->size = val;
• return size;

+}

+static DEVICE_ATTR_RW(buffer_size);

static struct attribute *coresight_tmc_attrs[] = { &dev_attr_trigger_cntr.attr,

• &dev_attr_buffer_size.attr, NULL,

}; -- 2.13.6