usb: atm: cxacru: Merge cxacru_upload_firmware() into cxacru_heavy_init()

After a recent change in clang to expose uninitialized warnings from
const variables [1], there is a warning in cxacru_heavy_init():

  drivers/usb/atm/cxacru.c:1104:6: error: variable 'bp' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
   1104 |         if (instance->modem_type->boot_rom_patch) {
        |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  drivers/usb/atm/cxacru.c:1113:39: note: uninitialized use occurs here
   1113 |         cxacru_upload_firmware(instance, fw, bp);
        |                                              ^~
  drivers/usb/atm/cxacru.c:1104:2: note: remove the 'if' if its condition is always true
   1104 |         if (instance->modem_type->boot_rom_patch) {
        |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  drivers/usb/atm/cxacru.c:1095:32: note: initialize the variable 'bp' to silence this warning
   1095 |         const struct firmware *fw, *bp;
        |                                       ^
        |                                        = NULL

While the warning is technically correct that bp is conditionally passed
uninitialized to cxacru_upload_firmware(), it is ultimately a false
positive warning on the uninitialized use of bp because the same
condition that initializes bp, instance->modem_type->boot_rom_patch, is
the same one that gates the use of bp within cxacru_upload_firmware().
As this warning occurs in clang's frontend before inlining occurs, it
cannot know that these conditions are indentical to avoid the warning.

Manually inline cxacru_upload_firmware() into cxacru_heavy_init(), as
that is its only callsite, so that clang can see that bp is initialized
and used under the same condition, clearing up the warning without any
functional changes to the code (LLVM was already doing this inlining
later).

Cc: [email protected]
Fixes: 1b0e614 ("[PATCH] USB ATM: driver for the Conexant AccessRunner chipset cxacru")
Closes: ClangBuiltLinux/linux#2102
Link: llvm/llvm-project@2464313 [1]
Signed-off-by: Nathan Chancellor <[email protected]>
Link: https://lore.kernel.org/r/20250722-usb-cxacru-fix-clang-21-uninit-warning-v2-1-6708a18decd2@kernel.org
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: nathanchance

drivers/usb/atm/cxacru.c

@@ -980,49 +980,84 @@ static int cxacru_fw(struct usb_device *usb_dev, enum cxacru_fw_request fw,
 	return ret;
 }
 
-static void cxacru_upload_firmware(struct cxacru_data *instance,
-				   const struct firmware *fw,
-				   const struct firmware *bp)
+
+static int cxacru_find_firmware(struct cxacru_data *instance,
+				char *phase, const struct firmware **fw_p)
 {
-	int ret;
+	struct usbatm_data *usbatm = instance->usbatm;
+	struct device *dev = &usbatm->usb_intf->dev;
+	char buf[16];
+
+	sprintf(buf, "cxacru-%s.bin", phase);
+	usb_dbg(usbatm, "cxacru_find_firmware: looking for %s\n", buf);
+
+	if (request_firmware(fw_p, buf, dev)) {
+		usb_dbg(usbatm, "no stage %s firmware found\n", phase);
+		return -ENOENT;
+	}
+
+	usb_info(usbatm, "found firmware %s\n", buf);
+
+	return 0;
+}
+
+static int cxacru_heavy_init(struct usbatm_data *usbatm_instance,
+			     struct usb_interface *usb_intf)
+{
+	const struct firmware *fw, *bp;
+	struct cxacru_data *instance = usbatm_instance->driver_data;
 	struct usbatm_data *usbatm = instance->usbatm;
 	struct usb_device *usb_dev = usbatm->usb_dev;
 	__le16 signature[] = { usb_dev->descriptor.idVendor,
 			       usb_dev->descriptor.idProduct };
 	__le32 val;
+	int ret;
 
-	usb_dbg(usbatm, "%s\n", __func__);
+	ret = cxacru_find_firmware(instance, "fw", &fw);
+	if (ret) {
+		usb_warn(usbatm_instance, "firmware (cxacru-fw.bin) unavailable (system misconfigured?)\n");
+		return ret;
+	}
+
+	if (instance->modem_type->boot_rom_patch) {
+		ret = cxacru_find_firmware(instance, "bp", &bp);
+		if (ret) {
+			usb_warn(usbatm_instance, "boot ROM patch (cxacru-bp.bin) unavailable (system misconfigured?)\n");
+			release_firmware(fw);
+			return ret;
+		}
+	}
 
 	/* FirmwarePllFClkValue */
 	val = cpu_to_le32(instance->modem_type->pll_f_clk);
 	ret = cxacru_fw(usb_dev, FW_WRITE_MEM, 0x2, 0x0, PLLFCLK_ADDR, (u8 *) &val, 4);
 	if (ret) {
 		usb_err(usbatm, "FirmwarePllFClkValue failed: %d\n", ret);
-		return;
+		goto done;
 	}
 
 	/* FirmwarePllBClkValue */
 	val = cpu_to_le32(instance->modem_type->pll_b_clk);
 	ret = cxacru_fw(usb_dev, FW_WRITE_MEM, 0x2, 0x0, PLLBCLK_ADDR, (u8 *) &val, 4);
 	if (ret) {
 		usb_err(usbatm, "FirmwarePllBClkValue failed: %d\n", ret);
-		return;
+		goto done;
 	}
 
 	/* Enable SDRAM */
 	val = cpu_to_le32(SDRAM_ENA);
 	ret = cxacru_fw(usb_dev, FW_WRITE_MEM, 0x2, 0x0, SDRAMEN_ADDR, (u8 *) &val, 4);
 	if (ret) {
 		usb_err(usbatm, "Enable SDRAM failed: %d\n", ret);
-		return;
+		goto done;
 	}
 
 	/* Firmware */
 	usb_info(usbatm, "loading firmware\n");
 	ret = cxacru_fw(usb_dev, FW_WRITE_MEM, 0x2, 0x0, FW_ADDR, fw->data, fw->size);
 	if (ret) {
 		usb_err(usbatm, "Firmware upload failed: %d\n", ret);
-		return;
+		goto done;
 	}
 
 	/* Boot ROM patch */
@@ -1031,15 +1066,15 @@ static void cxacru_upload_firmware(struct cxacru_data *instance,
 		ret = cxacru_fw(usb_dev, FW_WRITE_MEM, 0x2, 0x0, BR_ADDR, bp->data, bp->size);
 		if (ret) {
 			usb_err(usbatm, "Boot ROM patching failed: %d\n", ret);
-			return;
+			goto done;
 		}
 	}
 
 	/* Signature */
 	ret = cxacru_fw(usb_dev, FW_WRITE_MEM, 0x2, 0x0, SIG_ADDR, (u8 *) signature, 4);
 	if (ret) {
 		usb_err(usbatm, "Signature storing failed: %d\n", ret);
-		return;
+		goto done;
 	}
 
 	usb_info(usbatm, "starting device\n");
@@ -1051,7 +1086,7 @@ static void cxacru_upload_firmware(struct cxacru_data *instance,
 	}
 	if (ret) {
 		usb_err(usbatm, "Passing control to firmware failed: %d\n", ret);
-		return;
+		goto done;
 	}
 
 	/* Delay to allow firmware to start up. */
@@ -1065,53 +1100,10 @@ static void cxacru_upload_firmware(struct cxacru_data *instance,
 	ret = cxacru_cm(instance, CM_REQUEST_CARD_GET_STATUS, NULL, 0, NULL, 0);
 	if (ret < 0) {
 		usb_err(usbatm, "modem failed to initialize: %d\n", ret);
-		return;
-	}
-}
-
-static int cxacru_find_firmware(struct cxacru_data *instance,
-				char *phase, const struct firmware **fw_p)
-{
-	struct usbatm_data *usbatm = instance->usbatm;
-	struct device *dev = &usbatm->usb_intf->dev;
-	char buf[16];
-
-	sprintf(buf, "cxacru-%s.bin", phase);
-	usb_dbg(usbatm, "cxacru_find_firmware: looking for %s\n", buf);
-
-	if (request_firmware(fw_p, buf, dev)) {
-		usb_dbg(usbatm, "no stage %s firmware found\n", phase);
-		return -ENOENT;
-	}
-
-	usb_info(usbatm, "found firmware %s\n", buf);
-
-	return 0;
-}
-
-static int cxacru_heavy_init(struct usbatm_data *usbatm_instance,
-			     struct usb_interface *usb_intf)
-{
-	const struct firmware *fw, *bp;
-	struct cxacru_data *instance = usbatm_instance->driver_data;
-	int ret = cxacru_find_firmware(instance, "fw", &fw);
-
-	if (ret) {
-		usb_warn(usbatm_instance, "firmware (cxacru-fw.bin) unavailable (system misconfigured?)\n");
-		return ret;
+		goto done;
 	}
 
-	if (instance->modem_type->boot_rom_patch) {
-		ret = cxacru_find_firmware(instance, "bp", &bp);
-		if (ret) {
-			usb_warn(usbatm_instance, "boot ROM patch (cxacru-bp.bin) unavailable (system misconfigured?)\n");
-			release_firmware(fw);
-			return ret;
-		}
-	}
-
-	cxacru_upload_firmware(instance, fw, bp);
-
+done:
 	if (instance->modem_type->boot_rom_patch)
 		release_firmware(bp);
 	release_firmware(fw);