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    SubjectRe: [PATCH v2 25/27] coresight: etr_buf: Add helper for padding an area of trace data
    On Tue, May 01, 2018 at 10:10:55AM +0100, Suzuki K Poulose wrote:
    > This patch adds a helper to insert barrier packets for a given
    > size (aligned to packet size) at given offset in an etr_buf. This
    > will be used later for perf mode when we try to start in the
    > middle of an SG buffer.
    >
    > Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
    > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
    > ---
    > drivers/hwtracing/coresight/coresight-tmc-etr.c | 53 ++++++++++++++++++++++---
    > 1 file changed, 47 insertions(+), 6 deletions(-)
    >
    > diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
    > index 7551272..8159e84 100644
    > --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
    > +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
    > @@ -1083,18 +1083,59 @@ static ssize_t tmc_etr_buf_get_data(struct etr_buf *etr_buf,
    > return etr_buf->ops->get_data(etr_buf, (u64)offset, len, bufpp);
    > }
    >
    > +/*
    > + * tmc_etr_buf_insert_barrier_packets : Insert barrier packets at @offset upto
    > + * @size of bytes in the given buffer. @size should be aligned to the barrier
    > + * packet size.
    > + *
    > + * Returns the new @offset after filling the barriers on success. Otherwise
    > + * returns error.
    > + */
    > static inline s64
    > -tmc_etr_buf_insert_barrier_packet(struct etr_buf *etr_buf, u64 offset)
    > +tmc_etr_buf_insert_barrier_packets(struct etr_buf *etr_buf,
    > + u64 offset, u64 size)
    > {
    > ssize_t len;
    > char *bufp;
    >
    > - len = tmc_etr_buf_get_data(etr_buf, offset,
    > - CORESIGHT_BARRIER_PKT_SIZE, &bufp);
    > - if (WARN_ON(len <= CORESIGHT_BARRIER_PKT_SIZE))
    > + if (size < CORESIGHT_BARRIER_PKT_SIZE)
    > return -EINVAL;
    > - coresight_insert_barrier_packet(bufp);
    > - return offset + CORESIGHT_BARRIER_PKT_SIZE;
    > + /*
    > + * Normally the size should be aligned to the frame size
    > + * of the ETR. Even if it isn't, the decoder looks for a
    > + * barrier packet at a frame size aligned offset. So align
    > + * the buffer to frame size first and then fill barrier
    > + * packets.
    > + */
    > + do {
    > + len = tmc_etr_buf_get_data(etr_buf, offset, size, &bufp);
    > + if (WARN_ON(len <= 0))
    > + return -EINVAL;
    > + /*
    > + * We are guaranteed that @bufp will point to a linear range
    > + * of @len bytes, where @len <= @size.
    > + */
    > + size -= len;
    > + offset += len;
    > + while (len >= CORESIGHT_BARRIER_PKT_SIZE) {
    > + coresight_insert_barrier_packet(bufp);
    > + bufp += CORESIGHT_BARRIER_PKT_SIZE;
    > + len -= CORESIGHT_BARRIER_PKT_SIZE;
    > + }
    > +
    > + /* If we reached the end of the buffer, wrap around */
    > + if (offset == etr_buf->size)
    > + offset -= etr_buf->size;
    > + } while (size);
    > +
    > + return offset;
    > +}
    > +
    > +static inline s64
    > +tmc_etr_buf_insert_barrier_packet(struct etr_buf *etr_buf, u64 offset)
    > +{
    > + return tmc_etr_buf_insert_barrier_packets(etr_buf, offset,
    > + CORESIGHT_BARRIER_PKT_SIZE);

    Indentation

    > }
    >
    > /*
    > --
    > 2.7.4
    >

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