Enable configuration of PWM frequency for IS31FL3733B (#14983)

* Enable PWM frequency for IS31FL3733B

* Document config option

* clang

docs/feature_rgb_matrix.md

@@ -82,6 +82,7 @@ You can use between 1 and 4 IS31FL3733 IC's. Do not specify `DRIVER_ADDR_<N>` de
 |----------|-------------|---------|
 | `ISSI_TIMEOUT` | (Optional) How long to wait for i2c messages, in milliseconds | 100 |
 | `ISSI_PERSISTENCE` | (Optional) Retry failed messages this many times | 0 |
+| `ISSI_PWM_FREQUENCY` | (Optional) PWM Frequency Setting - IS31FL3733B only | 0 |
 | `DRIVER_COUNT` | (Required) How many RGB driver IC's are present | |
 | `DRIVER_LED_TOTAL` | (Required) How many RGB lights are present across all drivers | |
 | `DRIVER_ADDR_1` | (Required) Address for the first RGB driver | |

drivers/led/issi/is31fl3733.c

@@ -56,6 +56,10 @@
 #    define ISSI_PERSISTENCE 0
 #endif
 
+#ifndef ISSI_PWM_FREQUENCY
+#    define ISSI_PWM_FREQUENCY 0b000  // PFS - IS31FL3733B only
+#endif
+
 // Transfer buffer for TWITransmitData()
 uint8_t g_twi_transfer_buffer[20];
 
@@ -157,7 +161,7 @@ void IS31FL3733_init(uint8_t addr, uint8_t sync) {
     // Set global current to maximum.
     IS31FL3733_write_register(addr, ISSI_REG_GLOBALCURRENT, 0xFF);
     // Disable software shutdown.
-    IS31FL3733_write_register(addr, ISSI_REG_CONFIGURATION, (sync << 6) | 0x01);
+    IS31FL3733_write_register(addr, ISSI_REG_CONFIGURATION, ((sync & 0b11) << 6) | ((ISSI_PWM_FREQUENCY & 0b111) << 3) | 0x01);
 
     // Wait 10ms to ensure the device has woken up.
     wait_ms(10);