On 21/03/2023 17:56, Mike Leach wrote:
Hi James
On Thu, 16 Mar 2023 at 17:12, Suzuki K Poulose suzuki.poulose@arm.com wrote:
On 10/03/2023 16:06, James Clark wrote:
Add a function for adding connections dynamically. This also removes the 1:1 mapping between port number and the index into the connections array. The only place this mapping was used was in the warning for duplicate output ports, which has been replaced by a search. Other uses of the port number already use the port member variable.
Being able to dynamically add connections will allow other devices like CTI to re-use the connection mechanism despite not having explicit connections described in the DT.
Signed-off-by: James Clark james.clark@arm.com
.../hwtracing/coresight/coresight-platform.c | 77 ++++++++++++++----- include/linux/coresight.h | 7 +- 2 files changed, 64 insertions(+), 20 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c index c77238cdf448..16553f7dde12 100644 --- a/drivers/hwtracing/coresight/coresight-platform.c +++ b/drivers/hwtracing/coresight/coresight-platform.c @@ -27,8 +27,9 @@ static int coresight_alloc_conns(struct device *dev, struct coresight_platform_data *pdata) { if (pdata->nr_outconns) {
pdata->out_conns = devm_kcalloc(dev, pdata->nr_outconns,sizeof(*pdata->out_conns), GFP_KERNEL);
pdata->out_conns = devm_krealloc_array(dev, pdata->out_conns, pdata->nr_outconns,super minor nit: pdata->out_conns = devm_krealloc_array(dev,
sizeof(*pdata->out_conns), GFP_KERNEL | __GFP_ZERO); if (!pdata->out_conns) return -ENOMEM; }@@ -36,6 +37,48 @@ static int coresight_alloc_conns(struct device *dev, return 0; }
+/*
- Add a connection in the first free slot, or realloc
- if there is no space. @conn's contents is copied into the new slot.
- If the output port is already assigned on this device, return -EINVAL
- */
+int coresight_add_conn(struct device *dev,
struct coresight_platform_data *pdata,const struct coresight_connection *conn)+{
int ret;struct coresight_connection *free_conn = NULL;struct coresight_connection *i;/** Search for a free slot, and while looking for one, warn* on any existing duplicate output port.*/for (i = pdata->out_conns; i < pdata->out_conns + pdata->nr_outconns;++i) {minor nit: I see why you have gone against using "i" as index into the array. But I think having that as the index is still better readable.
for (i = 0; i < pdata->nr_outconns; i++) { struct coresight_connection *c = &pdata->out_conns[i];
if (i->remote_fwnode && conn->port != -1 &&i->port == conn->port) {dev_warn(dev, "Duplicate output port %d\n", i->port);return -EINVAL;}This code assumes that slots are filled sequentially and that it is not possible to release slots out of order - i.e. if we find a free slot, there is not a match in a later slot. I can't think how this could happen but a comment to confirm this might be needed here.
When we had 1:1 port / array index then this check was guaranteed
Mike
I thought about this but I couldn't see an issue here. The loop always runs to the end even if a free slot is found so it should find duplicates in any order. Unless I'm missing some other edge case?
if (!i->remote_fwnode && !free_conn)free_conn = i;}if (!free_conn) {and: /* No free slots */ if (i == pdata->nr_outconns) {
pdata->nr_outconns++;ret = coresight_alloc_conns(dev, pdata);if (ret)return ret;free_conn = &pdata->out_conns[pdata->nr_outconns - 1];}and: pdata->out_conns[i] = *conn;
Otherwise looks good to me.
Suzuki
-- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK