Re: [PATCH] coresight: tmc: Refactor loops in etb dump

On Wed, 5 Sep 2018 at 04:09, Leo Yan leo.yan@linaro.org wrote:

In ETB dump function tmc_etb_dump_hw() it has nested loops. The second level loop is to iterate index in the range [0 .. drvdata->memwidth); but the index isn't really used in the code, thus the second level loop is useless.

This patch is to remove the second level loop; the refactor also reduces indentation and we can use 'break' to replace 'goto' tag.

Cc: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Leo Yan leo.yan@linaro.org

---

drivers/hwtracing/coresight/coresight-tmc-etf.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c index 9c599c9..8b34161 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c @@ -34,23 +34,20 @@ static void tmc_etb_dump_hw(struct tmc_drvdata *drvdata) { char *bufp; u32 read_data, lost;

•   int i;
  
    /* Check if the buffer wrapped around. */
    lost = readl_relaxed(drvdata->base + TMC_STS) & TMC_STS_FULL;
    bufp = drvdata->buf;
    drvdata->len = 0;
    while (1) {
  

•           for (i = 0; i < drvdata->memwidth; i++) {
  

•                   read_data = readl_relaxed(drvdata->base + TMC_RRD);
  

•                   if (read_data == 0xFFFFFFFF)
  

•                           goto done;
  

•                   memcpy(bufp, &read_data, 4);
  

•                   bufp += 4;
  

•                   drvdata->len += 4;
  

•           }
  

•           read_data = readl_relaxed(drvdata->base + TMC_RRD);
  

•           if (read_data == 0xFFFFFFFF)
  

•                   break;
  

•           memcpy(bufp, &read_data, 4);
  

•           bufp += 4;
  

•           drvdata->len += 4;
  

I implemented these loops in accordance with the reference manual, which is advising to read one ETB memory word at a time. But taking a step back getting rid of the inner loop yields exactly the same result. So I'll go ahead and apply your patch.

Thanks, Mathieu

    }

-done:

•   if (lost)
            coresight_insert_barrier_packet(drvdata->buf);
    return;
  

-- 2.7.4