Re: [PATCH 10/11] firmware: arm_scmi: Use bound iterators to minimize discovered rates
From: Jonathan Cameron <jonathan.cameron@huawei.com>
Date: 2026-02-27 16:53:43
Also in:
arm-scmi, linux-clk, linux-renesas-soc, lkml
On Fri, 27 Feb 2026 15:32:24 +0000 Cristian Marussi [off-list ref] wrote:
Clock rates are guaranteed to be returned in ascending order for SCMI clock protocol versions greater than 1.0: in such a case, use bounded iterators to minimize the number of message exchanges needed to discover min and max rate. Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
+
+static int
+scmi_clock_describe_rates_get(const struct scmi_protocol_handle *ph,
+ u32 clk_id, struct clock_info *cinfo)
+{
+ struct scmi_clock_desc *clkd = &cinfo->clkds[clk_id];
+ int ret;
+
+ /*
+ * Since only after SCMI Clock v1.0 the returned rates are guaranteed to
+ * be discovered in ascending order, lazy enumeration cannot be use for
+ * SCMI Clock v1.0 protocol.
+ */
+ if (PROTOCOL_REV_MAJOR(ph->version) > 0x1)
+ ret = scmi_clock_describe_rates_get_lazy(ph, clkd);
+ else
+ ret = scmi_clock_describe_rates_get_full(ph, clkd);
+
+ if (ret)
+ return ret;
+
+ clkd->info.min_rate = clkd->rates[RATE_MIN];
if (!clkd->rate_discrete) {
clkd->info.max_rate = clkd->rates[RATE_MAX];
dev_dbg(ph->dev, "Min %llu Max %llu Step %llu Hz\n",
clkd->rates[RATE_MIN], clkd->rates[RATE_MAX],
clkd->rates[RATE_STEP]);
} else {
- sort(clkd->rates, clkd->num_rates,
- sizeof(clkd->rates[0]), rate_cmp_func, NULL);
clkd->info.max_rate = clkd->rates[clkd->num_rates - 1];
+ dev_dbg(ph->dev, "Clock:%s DISCRETE:%d -> Min %llu Max %llu\n",
+ clkd->info.name, clkd->rate_discrete,
+ clkd->info.min_rate, clkd->info.max_rate);
}
- clkd->info.min_rate = clkd->rates[RATE_MIN];
- return 0;
+ return ret;Why? Far as I can see it's still always zero if you get here.
} static int