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pm: handle the case of 2MHz frequency

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It is not possible to generate 1 MHz REF_TICK from 2 MHz APB clock
(this is a limitation of REF_TICK divider circuit). Since switching
REF_TICK frequency is something we would like to avoid (to maintain
UART output even with DFS), 2 MHz frequency has been marked as
unsupported.
This commit is contained in:
Ivan Grokhotkov 2018-03-27 10:52:38 +08:00
parent 839c665c92
commit 94014a9a51
1 changed files with 9 additions and 3 deletions
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12
components/esp32/pm_esp32.c
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@ -180,6 +180,12 @@ esp_err_t esp_pm_configure(const void* vconfig)
if (config->light_sleep_enable) {
return ESP_ERR_NOT_SUPPORTED;
}
if (config->min_cpu_freq == RTC_CPU_FREQ_2M) {
/* Minimal APB frequency to achieve 1MHz REF_TICK frequency is 5 MHz */
return ESP_ERR_NOT_SUPPORTED;
}
rtc_cpu_freq_t min_freq = config->min_cpu_freq;
rtc_cpu_freq_t max_freq = config->max_cpu_freq;
int min_freq_mhz = rtc_clk_cpu_freq_value(min_freq);
@ -188,14 +194,14 @@ esp_err_t esp_pm_configure(const void* vconfig)
return ESP_ERR_INVALID_ARG;
}
rtc_cpu_freq_t apb_max_freq; /* CPU frequency in APB_MAX mode */
rtc_cpu_freq_t apb_max_freq = max_freq; /* CPU frequency in APB_MAX mode */
if (max_freq == RTC_CPU_FREQ_240M) {
/* We can't switch between 240 and 80/160 without disabling PLL,
* so use 240MHz CPU frequency when 80MHz APB frequency is requested.
*/
apb_max_freq = RTC_CPU_FREQ_240M;
} else {
/* Otherwise (max CPU frequency is 80MHz or 160MHz), can use 80MHz
} else if (max_freq == RTC_CPU_FREQ_160M || max_freq == RTC_CPU_FREQ_80M) {
/* Otherwise, can use 80MHz
* CPU frequency when 80MHz APB frequency is requested.
*/
apb_max_freq = RTC_CPU_FREQ_80M;