diff --git a/src/platforms/common/blackpill-f4/blackpill-f4.c b/src/platforms/common/blackpill-f4/blackpill-f4.c
index 6080f1eb6e4..d5aaf747aba 100644
--- a/src/platforms/common/blackpill-f4/blackpill-f4.c
+++ b/src/platforms/common/blackpill-f4/blackpill-f4.c
@@ -45,10 +45,11 @@ volatile uint32_t magic[2] __attribute__((section(".noinit")));
 
 void platform_init(void)
 {
-	/* Enable GPIO peripherals */
+	/* Enable peripherals */
 	rcc_periph_clock_enable(RCC_GPIOA);
 	rcc_periph_clock_enable(RCC_GPIOC);
 	rcc_periph_clock_enable(RCC_GPIOB);
+	rcc_periph_clock_enable(RCC_CRC);
 
 #ifndef BMP_BOOTLOADER
 	/* Blackpill board has a floating button on PA0. Pull it up and use as active-low. */
@@ -73,26 +74,19 @@ void platform_init(void)
 #endif
 	rcc_clock_setup_pll(&rcc_hse_25mhz_3v3[PLATFORM_CLOCK_FREQ]);
 
-	/* Enable peripherals */
-	rcc_periph_clock_enable(RCC_OTGFS);
-	rcc_periph_clock_enable(RCC_CRC);
-
 	/* Set up DM/DP pins. PA9/PA10 are not routed to USB-C. */
 	gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO11 | GPIO12);
 	gpio_set_af(GPIOA, GPIO_AF10, GPIO11 | GPIO12);
 
-	GPIOA_OSPEEDR &= 0x3c00000cU;
-	GPIOA_OSPEEDR |= 0x28000008U;
-
 	/* Set up TDI, TDO, TCK and TMS pins */
 	gpio_mode_setup(TDI_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, TDI_PIN);
 	gpio_mode_setup(TDO_PORT, GPIO_MODE_INPUT, GPIO_PUPD_NONE, TDO_PIN);
 	gpio_mode_setup(TCK_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, TCK_PIN);
 	gpio_mode_setup(TMS_PORT, GPIO_MODE_INPUT, GPIO_PUPD_NONE, TMS_PIN);
-	gpio_set_output_options(TDI_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_2MHZ, TDI_PIN);
-	gpio_set_output_options(TDO_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_2MHZ, TDO_PIN);
-	gpio_set_output_options(TCK_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_2MHZ, TCK_PIN);
-	gpio_set_output_options(TMS_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_2MHZ, TMS_PIN);
+	gpio_set_output_options(TDI_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_25MHZ, TDI_PIN);
+	gpio_set_output_options(TDO_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_25MHZ, TDO_PIN);
+	gpio_set_output_options(TCK_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_25MHZ, TCK_PIN);
+	gpio_set_output_options(TMS_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_25MHZ, TMS_PIN);
 
 	/* Set up LED pins */
 	gpio_mode_setup(LED_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, LED_IDLE_RUN | LED_ERROR | LED_BOOTLOADER);
@@ -114,6 +108,9 @@ void platform_init(void)
 	/* https://github.com/libopencm3/libopencm3/pull/1256#issuecomment-779424001 */
 	OTG_FS_GCCFG |= OTG_GCCFG_NOVBUSSENS | OTG_GCCFG_PWRDWN;
 	OTG_FS_GCCFG &= ~(OTG_GCCFG_VBUSBSEN | OTG_GCCFG_VBUSASEN);
+
+	/* By default, do not drive the SWD bus too fast. */
+	platform_max_frequency_set(3000000);
 }
 
 void platform_nrst_set_val(bool assert)
diff --git a/src/platforms/common/blackpill-f4/usbdfu.c b/src/platforms/common/blackpill-f4/usbdfu.c
index b6f5cfa8991..d5d205ea968 100644
--- a/src/platforms/common/blackpill-f4/usbdfu.c
+++ b/src/platforms/common/blackpill-f4/usbdfu.c
@@ -42,6 +42,7 @@ void dfu_detach(void)
 
 int main(void)
 {
+	/* Enable GPIO peripherals */
 	rcc_periph_clock_enable(RCC_GPIOA);
 
 	/* Blackpill board has a floating button on PA0. Pull it up and use as active-low. */
@@ -63,9 +64,6 @@ int main(void)
 	/* Run heartbeat on blue LED */
 	sys_tick_init();
 
-	/* Enable peripherals */
-	rcc_periph_clock_enable(RCC_OTGFS);
-
 	/* Set up USB Pins and alternate function*/
 	gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO11 | GPIO12);
 	gpio_set_af(GPIOA, GPIO_AF10, GPIO11 | GPIO12);