Re: [PATCH v2 25/27] coresight: etr_buf: Add helper for padding an area of trace data

[Mathieu Poirier]

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.poir...@linaro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poul...@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
>