linux-kernel - [PATCH] ALSA: hda/ca0132: work around clang -Wuninitialized warning

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Date:   Fri, 22 Mar 2019 15:06:28 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Takashi Iwai <tiwai@...e.com>,
        Connor McAdams <conmanx360@...il.com>,
        Takashi Sakamoto <o-takashi@...amocchi.jp>
Cc:     clang-built-linux@...glegroups.com,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        Jaroslav Kysela <perex@...ex.cz>,
        Alastair Bridgewater <alastair.bridgewater@...il.com>,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: [PATCH] ALSA: hda/ca0132: work around clang -Wuninitialized warning

When CONFIG_PCI is disabled, clang gets confused about the
control flow of the switch() statement always ending up
in the default case, and warns:

sound/pci/hda/patch_ca0132.c:7558:6: error: variable 'fw_entry' is used uninitialized whenever 'if' condition is false
      [-Werror,-Wsometimes-uninitialized]
        if (!spec->alt_firmware_present) {
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~
sound/pci/hda/patch_ca0132.c:7565:42: note: uninitialized use occurs here
        dsp_os_image = (struct dsp_image_seg *)(fw_entry->data);
                                                ^~~~~~~~
sound/pci/hda/patch_ca0132.c:7558:2: note: remove the 'if' if its condition is always true
        if (!spec->alt_firmware_present) {
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sound/pci/hda/patch_ca0132.c:7521:33: note: initialize the variable 'fw_entry' to silence this warning
        const struct firmware *fw_entry;
                                       ^
                                        = NULL

Adding an explicit check for CONFIG_PCI avoids the issue.
Unfortunately this is not very intuitive here.

Link: https://bugs.llvm.org/show_bug.cgi?id=41197#c1
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
Any suggestions for other workarounds appreciated. If you can think
of a better fix, please treat this as a reported-by:
---
 sound/pci/hda/patch_ca0132.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/pci/hda/patch_ca0132.c b/sound/pci/hda/patch_ca0132.c
index 29882bda7632..415b16b7db70 100644
--- a/sound/pci/hda/patch_ca0132.c
+++ b/sound/pci/hda/patch_ca0132.c
@@ -7555,7 +7555,7 @@ static bool ca0132_download_dsp_images(struct hda_codec *codec)
 	 * Use default ctefx.bin if no alt firmware is detected, or if none
 	 * exists for your particular codec.
 	 */
-	if (!spec->alt_firmware_present) {
+	if (!IS_ENABLED(CONFIG_PCI) || !spec->alt_firmware_present) {
 		codec_dbg(codec, "Default firmware selected.");
 		if (request_firmware(&fw_entry, EFX_FILE,
 					codec->card->dev) != 0)
-- 
2.20.0