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

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