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SubjectRe: [PATCH v2 5/9] coresight: Dynamically add connections
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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 duplicate output ports, which has been replaced by a search.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;
> + }
> + 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


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