From 0402f75efe4719bca950900275100d9a12f44a92 Mon Sep 17 00:00:00 2001 From: Mathieu Poirier Date: Wed, 19 Jun 2019 11:29:07 -0600 Subject: coresight: tmc-etf: Properly set AUX buffer head in snapshot mode Unify amongst sink drivers how the AUX ring buffer head is communicated to user space. That way the same algorithm in user space can be used to determine where the latest data is and how much of it to access. Signed-off-by: Mathieu Poirier Reviewed-by: Suzuki K Poulose Tested-by: Leo Yan Signed-off-by: Greg Kroah-Hartman --- drivers/hwtracing/coresight/coresight-tmc-etf.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) (limited to 'drivers/hwtracing/coresight/coresight-tmc-etf.c') diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c index 2527b5d3b65e..d026bd04a6af 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c @@ -542,11 +542,15 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev, } } - /* In snapshot mode we have to update the head */ - if (buf->snapshot) { - handle->head = (cur * PAGE_SIZE) + offset; - to_read = buf->nr_pages << PAGE_SHIFT; - } + /* + * In snapshot mode we simply increment the head by the number of byte + * that were written. User space function cs_etm_find_snapshot() will + * figure out how many bytes to get from the AUX buffer based on the + * position of the head. + */ + if (buf->snapshot) + handle->head += to_read; + CS_LOCK(drvdata->base); out: spin_unlock_irqrestore(&drvdata->spinlock, flags); -- cgit v1.2.3-59-g8ed1b