Re: [PATCH v5 4/5] interconnect: qcom: Add QCS404 interconnect provider driver

On Sun, Aug 25, 2019 at 04:41:55PM -0400, Brian Masney wrote:

Hi Georgi and Bjorn,

I'm finishing up a msm8974 interconnect driver and I used qcs404 as a
starting point. I have a question below.

On Tue, Jul 23, 2019 at 05:23:38PM +0300, Georgi Djakov wrote:

quoted

From: Bjorn Andersson <redacted>

Add driver for the interconnect buses found in Qualcomm QCS404-based
platforms. The topology consists of three NoCs that are controlled by
a remote processor. This remote processor collects the aggregated
bandwidth for each master-slave pairs.

Signed-off-by: Bjorn Andersson <redacted>
Signed-off-by: Georgi Djakov <redacted>
---

[snip]

quoted

+enum {
+       QCS404_MASTER_AMPSS_M0 = 1,

[snip]

quoted

+#define DEFINE_QNODE(_name, _id, _buswidth, _mas_rpm_id, _slv_rpm_id,	\
+		     ...)						\
+		static struct qcom_icc_node _name = {			\
+		.name = #_name,						\
+		.id = _id,						\
+		.buswidth = _buswidth,					\
+		.mas_rpm_id = _mas_rpm_id,				\
+		.slv_rpm_id = _slv_rpm_id,				\
+		.num_links = ARRAY_SIZE(((int[]){ __VA_ARGS__ })),	\
+		.links = { __VA_ARGS__ },				\
+	}
+
+DEFINE_QNODE(mas_apps_proc, QCS404_MASTER_AMPSS_M0, 8, 0, -1, QCS404_SLAVE_EBI_CH0, QCS404_BIMC_SNOC_SLV);

[snip]

quoted

+static struct qcom_icc_node *qcs404_bimc_nodes[] = {
+	[MASTER_AMPSS_M0] = &mas_apps_proc,

Should the id in DEFINE_QNODE() above be MASTER_AMPSS_M0 instead of
QCS404_MASTER_AMPSS_M0?

of_icc_xlate_onecell() looks up the id by the array index
MASTER_AMPSS_M0 (1), however qnoc_probe() passes the id that's
in struct qcom_icc_node to icc_node_create(), which is
QCS404_MASTER_AMPSS_M0 (0). They have different values and I'm unsure
why we can't just use the ids that are in qcom,qcs404.h and drop the
enum above.

I dug through the interconnect code some more and I now see why these
separate IDs are needed.

I posted a work in progress msm8974 interconnect driver:
https://lore.kernel.org/lkml/20190902211925.27169-1-masneyb@onstation.org/T/#t (local)

Brian