power: fix current frequency index

During power initialization the pstate cpufreq api is
not setting the initial curr_idx of pstate_power_info
to corresponding current frequency index.

Without this the idx is always 0, which is causing the
below check to pass and returns without setting the initial
min/max frequency to system max frequency and this leads to
incorrect frequency settings when power_pstate_cpufreq_set_freq()
is called in the apps.

set_freq_internal(struct pstate_power_info *pi, uint32_t idx)
{
...

 /* Check if it is the same as current */
        if (idx == pi->curr_idx)
                return 0;
...
}

scenario 1:
If system has starting scaling min/max: 1000/1000, and want to
set this to 2200/2200, the max frequency gets updated but not min.

scenario 2:
If system has starting scaling min/max: 2200/1000, and want to set
to 2200/2200, the max, min frequency was not updated. Since no change
in max that should be ok, but min was also ignored, which will be fixed
now with the new changes.

Fixes: e6c6dc0f ("power: add p-state driver compatibility")
Cc: stable@dpdk.org
Signed-off-by: Reshma Pattan <reshma.pattan@intel.com>
Reviewed-by: Liang Ma <liang.j.ma@intel.com>

diff --git a/lib/librte_power/power_pstate_cpufreq.c b/lib/librte_power/power_pstate_cpufreq.c
index e3126d3..edf6328 100644 (file)
--- a/lib/librte_power/power_pstate_cpufreq.c
+++ b/lib/librte_power/power_pstate_cpufreq.c
@@ -51,6 +51,9 @@
                } \
 } while (0)
 
+/* macros used for rounding frequency to nearest 100000 */
+#define FREQ_ROUNDING_DELTA 50000
+#define ROUND_FREQ_TO_N_100000 100000
 
 #define POWER_CONVERT_TO_DECIMAL 10
 #define BUS_FREQ     100000
@@ -531,6 +534,57 @@ out:
        return ret;
 }
 
+static int
+power_get_cur_idx(struct pstate_power_info *pi)
+{
+       FILE *f_cur;
+       int ret = -1;
+       char *p_cur;
+       char buf_cur[BUFSIZ];
+       char fullpath_cur[PATH_MAX];
+       char *s_cur;
+       uint32_t sys_cur_freq = 0;
+       unsigned int i;
+
+       snprintf(fullpath_cur, sizeof(fullpath_cur),
+                       POWER_SYSFILE_CUR_FREQ,
+                       pi->lcore_id);
+       f_cur = fopen(fullpath_cur, "r");
+       FOPEN_OR_ERR_RET(f_cur, ret);
+
+       /* initialize the cur_idx to matching current frequency freq index */
+       s_cur = fgets(buf_cur, sizeof(buf_cur), f_cur);
+       FOPS_OR_NULL_GOTO(s_cur, fail);
+
+       p_cur = strchr(buf_cur, '\n');
+       if (p_cur != NULL)
+               *p_cur = 0;
+       sys_cur_freq = strtoul(buf_cur, &p_cur, POWER_CONVERT_TO_DECIMAL);
+
+       /* convert the frequency to nearest 100000 value
+        * Ex: if sys_cur_freq=1396789 then freq_conv=1400000
+        * Ex: if sys_cur_freq=800030 then freq_conv=800000
+        * Ex: if sys_cur_freq=800030 then freq_conv=800000
+        */
+       unsigned int freq_conv = 0;
+       freq_conv = (sys_cur_freq + FREQ_ROUNDING_DELTA)
+                               / ROUND_FREQ_TO_N_100000;
+       freq_conv = freq_conv * ROUND_FREQ_TO_N_100000;
+
+       for (i = 0; i < pi->nb_freqs; i++) {
+               if (freq_conv == pi->freqs[i]) {
+                       pi->curr_idx = i;
+                       break;
+               }
+       }
+
+       fclose(f_cur);
+       return 0;
+fail:
+       fclose(f_cur);
+       return ret;
+}
+
 int
 power_pstate_cpufreq_check_supported(void)
 {
@@ -586,6 +640,11 @@ power_pstate_cpufreq_init(unsigned int lcore_id)
                goto fail;
        }
 
+       if (power_get_cur_idx(pi) < 0) {
+               RTE_LOG(ERR, POWER, "Cannot get current frequency "
+                               "index of lcore %u\n", lcore_id);
+               goto fail;
+       }
 
        /* Set freq to max by default */
        if (power_pstate_cpufreq_freq_max(lcore_id) < 0) {