[PATCH v4] brcmfmac: firmware: Fix firmware loading

[Dmitry Osipenko <digetx@gmail.com>]

From: Linus Walleij <linus.walleij@linaro.org>

The patch that would first try the board-specific firmware
had a bug because the fallback would not be called: the
asynchronous interface is used meaning request_firmware_nowait()
returns 0 immediately.

Harden the firmware loading like this:

- If we cannot build an alt_path (like if no board_type is
  specified) just request the first firmware without any
  suffix, like in the past.

- If the lookup of a board specific firmware fails, we get
  a NULL fw in the async callback, so just try again without
  the alt_path from a dedicated brcm_fw_request_done_alt_path
  callback.

- Drop the unnecessary prototype of brcm_fw_request_done.

Fixes: 5ff013914c62 ("brcmfmac: firmware: Allow per-board firmware binaries")
Cc: Stefan Hansson <newbyte@disroot.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
ChangeLog v3->v4:
- Added brcmf_fw_request_done_alt_path() callback to replace the
  "tried_board_variant" variable, making code cleaner and errors
  handled consistently.
ChangeLog v2->v3:
- Rename state variable to "tried_board_variant".
ChangeLog v1->v2:
- Instead of using a static variable, add a context variable
  "tested_board_variant"
- Collect Arend's review tag.
- Collect Tested-by from Dmitry.
---
 .../broadcom/brcm80211/brcmfmac/firmware.c    | 24 ++++++++++++++-----
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
index adfdfc654b10..0eb13e5df517 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
@@ -431,8 +431,6 @@ struct brcmf_fw {
 	void (*done)(struct device *dev, int err, struct brcmf_fw_request *req);
 };
 
-static void brcmf_fw_request_done(const struct firmware *fw, void *ctx);
-
 #ifdef CONFIG_EFI
 /* In some cases the EFI-var stored nvram contains "ccode=ALL" or "ccode=XV"
  * to specify "worldwide" compatible settings, but these 2 ccode-s do not work
@@ -658,6 +656,22 @@ static void brcmf_fw_request_done(const struct firmware *fw, void *ctx)
 	kfree(fwctx);
 }
 
+static void brcmf_fw_request_done_alt_path(const struct firmware *fw, void *ctx)
+{
+	struct brcmf_fw *fwctx = ctx;
+	struct brcmf_fw_item *first = &fwctx->req->items[0];
+	int ret = 0;
+
+	/* Fall back to canonical path if board firmware not found */
+	if (!fw)
+		ret = request_firmware_nowait(THIS_MODULE, true, first->path,
+					      fwctx->dev, GFP_KERNEL, fwctx,
+					      brcmf_fw_request_done);
+
+	if (fw || ret < 0)
+		brcmf_fw_request_done(fw, ctx);
+}
+
 static bool brcmf_fw_request_is_valid(struct brcmf_fw_request *req)
 {
 	struct brcmf_fw_item *item;
@@ -702,11 +716,9 @@ int brcmf_fw_get_firmwares(struct device *dev, struct brcmf_fw_request *req,
 	if (alt_path) {
 		ret = request_firmware_nowait(THIS_MODULE, true, alt_path,
 					      fwctx->dev, GFP_KERNEL, fwctx,
-					      brcmf_fw_request_done);
+					      brcmf_fw_request_done_alt_path);
 		kfree(alt_path);
-	}
-	/* Else try canonical path */
-	if (ret) {
+	} else {
 		ret = request_firmware_nowait(THIS_MODULE, true, first->path,
 					      fwctx->dev, GFP_KERNEL, fwctx,
 					      brcmf_fw_request_done);
-- 
2.32.0