Re: [PATCH v3 02/11] coresight-tpda: Add DSB dataset support

Suzuki K Poulose
2023-03-23T11:52:04Z

On 23/03/2023 06:03, Tao Zhang wrote:
> Read the DSB element size from the device tree. Set the register
> bit that controls the DSB element size of the corresponding port.
>
> Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
> ---
> drivers/hwtracing/coresight/coresight-tpda.c | 58 ++++++++++++++++++++++++++++
> drivers/hwtracing/coresight/coresight-tpda.h | 4 ++
> 2 files changed, 62 insertions(+)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tpda.c b/drivers/hwtracing/coresight/coresight-tpda.c
> index f712e11..8dcfc4a 100644
> --- a/drivers/hwtracing/coresight/coresight-tpda.c
> +++ b/drivers/hwtracing/coresight/coresight-tpda.c
> @@ -21,6 +21,47 @@
>
> DEFINE_CORESIGHT_DEVLIST(tpda_devs, "tpda");
>
> +/* Search and read element data size from the TPDM node in
> + * the devicetree. Each input port of TPDA is connected to
> + * a TPDM. Different TPDM supports different types of dataset,
> + * and some may support more than one type of dataset.
> + * Parameter "inport" is used to pass in the input port number
> + * of TPDA, and it is set to 0 in the recursize call.
> + * Parameter "parent" is used to pass in the original call.
> + */

I am still not clear why we need to do this recursively ?

> +static int tpda_set_element_size(struct tpda_drvdata *drvdata,
> + struct coresight_device *csdev, int inport, bool parent)

Please could we renamse csdev => tpda_dev

> +{
> + static int nr_inport;
> + int i;
> + struct coresight_device *in_csdev;

similarly tpdm_dev ?

Could we not add a check here to see if the dsb_esize[inport] is already
set and then bail out, reading this over and over ?

> +
> + if (inport > (TPDA_MAX_INPORTS - 1))
> + return -EINVAL;
> +
> + if (parent)
> + nr_inport = inport;
> +
> + for (i = 0; i < csdev->pdata->nr_inconns; i++) {
> + in_csdev = csdev->pdata->in_conns[i].remote_dev;

Please note, the names of the structure field might change in the
next version of James' series

> + if (!in_csdev)
> + break;
> +
> + if (parent)
> + if (csdev->pdata->in_conns[i].port != inport)
> + continue;
> +
> + if (in_csdev && strstr(dev_name(&in_csdev->dev), "tpdm")) {

Isn't there a better way to distinguish a device to be TPDM ? May be we
could even add a source_sub_type - SOURCE_TPDM instead of using
SOURCE_OTHERS ? Do you expect other sources to be connected to TPDA?
e.g., STMs ?

> + of_property_read_u32(in_csdev->dev.parent->of_node,
> + "qcom,dsb-element-size", &drvdata->dsb_esize[nr_inport]);
> + break;
> + }
> + tpda_set_element_size(drvdata, in_csdev, 0, false);

What is the point of this ? Is this for covering the a TPDA connected to
another TPDA ?

e.g., { TPDM0, TPDM1 } -> TPDA0 -> TPDA1 ?

And you want to figure out the DSB size of TPDM0 when you want to enable
TPDA1 ? How do you choose between that size of TPDM0 vs TPDM1 ?

Please add a proper documentation for this function ? If TPDA0 is in the
the path, it should have been enabled before you reach TPDA1. Thus,
the dsb_esize array must have been initialised for TPDA0 and thus, you
could simply read it from the dsb_esize[] of TPDA0.
You could always look at the device_type and sub_type to detect a
TPDA{0} connected into TPDA{1}

> + }
> +
> + return 0;
> +}
> +
> /* Settings pre enabling port control register */
> static void tpda_enable_pre_port(struct tpda_drvdata *drvdata)
> {
> @@ -37,6 +78,18 @@ static void tpda_enable_port(struct tpda_drvdata *drvdata, int port)
> u32 val;
>
> val = readl_relaxed(drvdata->base + TPDA_Pn_CR(port));
> + /*
> + * Configure aggregator port n DSB data set element size
> + * Set the bit to 0 if the size is 32
> + * Set the bit to 1 if the size is 64
> + */
> + if (drvdata->dsb_esize[port] == 32)
> + val &= ~TPDA_Pn_CR_DSBSIZE;
> + else if (drvdata->dsb_esize[port] == 64)
> + val |= TPDA_Pn_CR_DSBSIZE;
> + else
> + dev_err(drvdata->dev,
> + "DSB data size input from port[%d] is invalid\n", port);

WARN_ON_ONCE() and abort the enable opration ? Or say, "fallback to
32bit or 64bit" if one of them is a safer option ? Please don't
leave it unknown.

> /* Enable the port */
> val |= TPDA_Pn_CR_ENA;
> writel_relaxed(val, drvdata->base + TPDA_Pn_CR(port));
> @@ -57,6 +110,11 @@ static void __tpda_enable(struct tpda_drvdata *drvdata, int port)
> static int tpda_enable(struct coresight_device *csdev, int inport, int outport)
> {
> struct tpda_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> + int ret;
> +
> + ret = tpda_set_element_size(drvdata, csdev, inport, true);
> + if (ret)
> + return ret;
>
> spin_lock(&drvdata->spinlock);
> if (atomic_read(&csdev->refcnt[inport]) == 0)
> diff --git a/drivers/hwtracing/coresight/coresight-tpda.h b/drivers/hwtracing/coresight/coresight-tpda.h
> index 0399678..9ec5870 100644
> --- a/drivers/hwtracing/coresight/coresight-tpda.h
> +++ b/drivers/hwtracing/coresight/coresight-tpda.h
> @@ -10,6 +10,8 @@
> #define TPDA_Pn_CR(n) (0x004 + (n * 4))
> /* Aggregator port enable bit */
> #define TPDA_Pn_CR_ENA BIT(0)
> +/* Aggregator port DSB data set element size bit */
> +#define TPDA_Pn_CR_DSBSIZE BIT(8)
>
> #define TPDA_MAX_INPORTS 32
>
> @@ -23,6 +25,7 @@
> * @csdev: component vitals needed by the framework.
> * @spinlock: lock for the drvdata value.
> * @enable: enable status of the component.
> + * @dsb_esize: DSB element size

Please state, must be 32 or 64.

> */
> struct tpda_drvdata {
> void __iomem *base;
> @@ -30,6 +33,7 @@ struct tpda_drvdata {
> struct coresight_device *csdev;
> spinlock_t spinlock;
> u8 atid;
> + u32 dsb_esize[TPDA_MAX_INPORTS];

Couldn't this be u8 ?

Suzuki

> };
>
> #endif /* _CORESIGHT_CORESIGHT_TPDA_H */