[PATCH v3 4/6] arch: arm: mach-snapdragon: Auto-detect USB SSPHY driver support
Balaji Selvanathan
balaji.selvanathan at oss.qualcomm.com
Wed Dec 3 12:07:33 CET 2025
Automatically detect super-speed USB PHY driver availability and
skip the USB speed fixup if driver is available, eliminating the need
for manual configuration.
Previously, U-Boot unconditionally limited USB to high-speed mode
on all Qualcomm platforms because most lacked super-speed PHY
drivers.
This change implements runtime detection that checks if a PHY
driver exists for the super-speed PHY node referenced by the DWC3
controller. The fixup is automatically skipped when a compatible
driver is found, allowing the hardware to operate at full
capability. Platforms without super-speed PHY drivers continue to
receive the fixup automatically.
---
v3:
- Removed support to manually disable the fixup via Kconfig.
- Instead added code to automatically detect if
SSPHY driver is available.
Signed-off-by: Balaji Selvanathan <balaji.selvanathan at oss.qualcomm.com>
---
arch/arm/mach-snapdragon/of_fixup.c | 130 ++++++++++++++++++++++++----
1 file changed, 112 insertions(+), 18 deletions(-)
diff --git a/arch/arm/mach-snapdragon/of_fixup.c b/arch/arm/mach-snapdragon/of_fixup.c
index eec2c0c757e..85dc1c4573d 100644
--- a/arch/arm/mach-snapdragon/of_fixup.c
+++ b/arch/arm/mach-snapdragon/of_fixup.c
@@ -4,7 +4,7 @@
*
* This file implements runtime fixups for Qualcomm DT to improve
* compatibility with U-Boot. This includes adjusting the USB nodes
- * to only use USB high-speed.
+ * to only use USB high-speed if SSPHY driver is not available.
*
* We use OF_LIVE for this rather than early FDT fixup for a couple
* of reasons: it has a much nicer API, is most likely more efficient,
@@ -21,32 +21,108 @@
#include <dt-bindings/input/linux-event-codes.h>
#include <dm/of_access.h>
#include <dm/of.h>
+#include <dm/device.h>
+#include <dm/lists.h>
#include <event.h>
#include <fdt_support.h>
#include <linux/errno.h>
+#include <linker_lists.h>
#include <stdlib.h>
#include <time.h>
-/* 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
- * porting process for new devices.
+/**
+ * find_ssphy_node() - Find the super-speed PHY node referenced by DWC3
+ * @dwc3: DWC3 device node
+ *
+ * Returns: Pointer to SS-PHY node if found, NULL otherwise
+ */
+static struct device_node *find_ssphy_node(struct device_node *dwc3)
+{
+ const __be32 *phandles;
+ const char *phy_name;
+ int len, i, ret;
+
+ phandles = of_get_property(dwc3, "phys", &len);
+ if (!phandles)
+ return NULL;
+
+ len /= sizeof(*phandles);
+
+ /* Iterate through PHY phandles to find the SS-PHY */
+ for (i = 0; i < len; i++) {
+ ret = of_property_read_string_index(dwc3, "phy-names", i, &phy_name);
+ if (ret)
+ continue;
+
+ /* Check if this is the super-speed PHY */
+ if (!strncmp("usb3-phy", phy_name, strlen("usb3-phy")) ||
+ !strncmp("usb3_phy", phy_name, strlen("usb3_phy"))) {
+ return of_find_node_by_phandle(NULL, be32_to_cpu(phandles[i]));
+ }
+ }
+
+ return NULL;
+}
+
+/**
+ * has_driver_for_node() - Check if any PHY driver can bind to this node
+ * @np: Device node to check
+ *
+ * Returns: true if a PHY driver with matching compatible string exists, false otherwise
*/
+static bool has_driver_for_node(struct device_node *np)
+{
+ struct driver *driver = ll_entry_start(struct driver, driver);
+ const int n_ents = ll_entry_count(struct driver, driver);
+ const char *compat_list, *compat;
+ int compat_length, i;
+ struct driver *entry;
+
+ if (!np)
+ return false;
+
+ /* Get compatible strings from the node */
+ compat_list = of_get_property(np, "compatible", &compat_length);
+ if (!compat_list)
+ return false;
+
+ /* Check each compatible string against PHY drivers only */
+ for (i = 0; i < compat_length; i += strlen(compat) + 1) {
+ compat = compat_list + i;
+
+ /* Iterate through all registered drivers */
+ for (entry = driver; entry != driver + n_ents; entry++) {
+ const struct udevice_id *of_match = entry->of_match;
+
+ /* Skip non-PHY drivers to improve performance */
+ if (entry->id != UCLASS_PHY)
+ continue;
+
+ if (!of_match)
+ continue;
+
+ while (of_match->compatible) {
+ if (!strcmp(of_match->compatible, compat)) {
+ debug("Found PHY driver '%s' for SS-PHY compatible '%s'\n",
+ entry->name, compat);
+ return true;
+ }
+ of_match++;
+ }
+ }
+ }
+
+ return false;
+}
+
static int fixup_qcom_dwc3(struct device_node *root, struct device_node *glue_np)
{
- struct device_node *dwc3;
+ struct device_node *dwc3, *ssphy_np;
int ret, len, hsphy_idx = 1;
const __be32 *phandles;
const char *second_phy_name;
- debug("Fixing up %s\n", glue_np->name);
-
- /* Tell the glue driver to configure the wrapper for high-speed only operation */
- ret = of_write_prop(glue_np, "qcom,select-utmi-as-pipe-clk", 0, NULL);
- if (ret) {
- log_err("Failed to add property 'qcom,select-utmi-as-pipe-clk': %d\n", ret);
- return ret;
- }
+ debug("Checking USB configuration for %s\n", glue_np->name);
/* Find the DWC3 node itself */
dwc3 = of_find_compatible_node(glue_np, NULL, "snps,dwc3");
@@ -58,20 +134,38 @@ static int fixup_qcom_dwc3(struct device_node *root, struct device_node *glue_np
phandles = of_get_property(dwc3, "phys", &len);
len /= sizeof(*phandles);
if (len == 1) {
- log_debug("Only one phy, not a superspeed controller\n");
+ debug("Only one phy, not a superspeed controller\n");
return 0;
}
- /* Figure out if the superspeed phy is present and if so then which phy is it? */
+ /* Figure out if the superspeed phy is present */
ret = of_property_read_string_index(dwc3, "phy-names", 1, &second_phy_name);
if (ret == -ENODATA) {
- log_debug("Only one phy, not a super-speed controller\n");
+ debug("Only one phy, not a super-speed controller\n");
return 0;
} else if (ret) {
log_err("Failed to read second phy name: %d\n", ret);
return ret;
}
+ /* Find the super-speed PHY node and check if a driver is available */
+ ssphy_np = find_ssphy_node(dwc3);
+ if (ssphy_np && has_driver_for_node(ssphy_np)) {
+ debug("Skipping USB fixup for %s (SS-PHY driver available)\n",
+ glue_np->name);
+ return 0;
+ }
+
+ /* No driver available - apply the fixup */
+ debug("Applying USB high-speed fixup to %s\n", glue_np->name);
+
+ /* Tell the glue driver to configure the wrapper for high-speed only operation */
+ ret = of_write_prop(glue_np, "qcom,select-utmi-as-pipe-clk", 0, NULL);
+ if (ret) {
+ log_err("Failed to add property 'qcom,select-utmi-as-pipe-clk': %d\n", ret);
+ return ret;
+ }
+
/*
* Determine which phy is the superspeed phy by checking the name of the second phy
* since it is typically the superspeed one.
@@ -150,7 +244,7 @@ static void fixup_power_domains(struct device_node *root)
do { \
u64 start = timer_get_us(); \
func(__VA_ARGS__); \
- debug(#func " took %lluus\n", timer_get_us() - start); \
+ printf(#func " took %lluus\n", timer_get_us() - start); \
} while (0)
static int qcom_of_fixup_nodes(void * __maybe_unused ctx, struct event *event)
--
2.34.1
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