On 11/26/2025 7:54 PM, Casey Connolly wrote:
Hi Balaji,
On 24/11/2025 16:55, Balaji Selvanathan wrote:
Add CONFIG_QCOM_USB_FIXUP option to allow platforms to disable
the USB speed limitation fixup when they have proper super-speed
USB support in U-Boot.
In general, we prefer to handle cases like this at runtime rather than
compile time. Could you rework this to check for the "qcom,sc7280-dwc3"
compatible and just skip the check in that case? I would also propose
adding a log_warning() in the fixup case so that folks working on other
platforms know to add their compatible too.
Obviously that's still not an ideal solution, maybe it would be possible
to implement the Super Smart (tm) fix and actually check if a driver
/will/ bind to the ss-phy node before the fixup, it depends how slow
that would be.
This is good idea. Actually, I have implemented the super smart fix
rather than hardcoding
"qcom,sc7280-dwc3" in code. The respined code is here:
https://lore.kernel.org/u-boot/[email protected]/;
The code checks if the SS PHY driver is indeed available and if it exists, then
it skips doing
USB HS fixup.
The entire time to check if the SS PHY driver is available is ~125ms. Request
to say if this is reasonable.
The power domain fixup is taking ~98us (mentioning just for comparison).
Thanks,
Balaji
Kind regards,
Currently, U-Boot limits USB to high-speed mode on all Qualcomm
platforms by fixing up the device tree at runtime. This was
necessary because most platforms lacked super-speed PHY drivers.
However, newer platforms now have proper QMP PHY drivers that support
super-speed USB. For these platforms, the fixup is counterproductive
as it prevents the hardware from operating at its full capability.
This change:
- Adds CONFIG_QCOM_USB_FIXUP (default y) to maintain backward
compatibility with existing platforms
- Wraps the fixup code with #ifdef to allow selective disabling
- Allows platforms with super-speed support to disable the fixup
via their defconfig
Platforms without super-speed PHY drivers will continue to work
as before with the fixup enabled by default.
Signed-off-by: Balaji Selvanathan <[email protected]>
---
arch/arm/mach-snapdragon/Kconfig | 10 ++++++++++
arch/arm/mach-snapdragon/of_fixup.c | 4 ++++
2 files changed, 14 insertions(+)
diff --git a/arch/arm/mach-snapdragon/Kconfig b/arch/arm/mach-snapdragon/Kconfig
index 976c0e35fce..6c53aeef597 100644
--- a/arch/arm/mach-snapdragon/Kconfig
+++ b/arch/arm/mach-snapdragon/Kconfig
@@ -29,6 +29,16 @@ config SYS_MALLOC_LEN
config LNX_KRNL_IMG_TEXT_OFFSET_BASE
default 0x80000000
+config QCOM_USB_FIXUP
+ bool "Enable USB speed fixup for Qualcomm platforms"
+ default y
+ help
+ Enable runtime fixup of USB device tree nodes to limit USB to
+ high-speed mode. This is needed on some Qualcomm platforms where
+ U-Boot doesn't support super-speed USB.
+ Disable this for platforms that have proper super-speed USB support
+ in U-Boot.
+
config SYS_BOARD
string "Snapdragon SoCs based board"
help
diff --git a/arch/arm/mach-snapdragon/of_fixup.c
b/arch/arm/mach-snapdragon/of_fixup.c
index eec2c0c757e..6a64168f67e 100644
--- a/arch/arm/mach-snapdragon/of_fixup.c
+++ b/arch/arm/mach-snapdragon/of_fixup.c
@@ -27,6 +27,7 @@
#include <stdlib.h>
#include <time.h>
+#ifdef CONFIG_QCOM_USB_FIXUP
/* U-Boot only supports USB high-speed mode on Qualcomm platforms with DWC3
* USB controllers. Rather than requiring source level DT changes, we fix up
* DT here. This improves compatibility with upstream DT and simplifies the
@@ -115,6 +116,7 @@ static void fixup_usb_nodes(struct device_node *root)
log_warning("Failed to fixup node %s: %d\n",
glue_np->name, ret);
}
}
+#endif
/* Remove all references to the rpmhpd device */
static void fixup_power_domains(struct device_node *root)
@@ -157,7 +159,9 @@ static int qcom_of_fixup_nodes(void * __maybe_unused ctx,
struct event *event)
{
struct device_node *root = event->data.of_live_built.root;
+#ifdef CONFIG_QCOM_USB_FIXUP
time_call(fixup_usb_nodes, root);
+#endif
time_call(fixup_power_domains, root);
return 0;
