Re: [PATCH v2 04/35] brcmfmac: firmware: Support having multiple alt paths

[Arend van Spriel <arend.vanspriel@broadcom.com>]

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On 1/4/2022 8:26 AM, Hector Martin wrote:
> Apple platforms have firmware and config files identified with multiple
> dimensions. We want to be able to find the most specific firmware
> available for any given platform, progressively trying more general
> firmwares.
> 
> First, add support for having multiple alternate firmware paths.

Reviewed-by: Arend van Spriel <arend.vanspriel@broadcom.com>
> Acked-by: Linus Walleij <linus.walleij@linaro.org>
> Signed-off-by: Hector Martin <marcan@marcan.st>
> ---
>   .../broadcom/brcm80211/brcmfmac/firmware.c    | 75 ++++++++++++++-----
>   .../broadcom/brcm80211/brcmfmac/firmware.h    |  2 +
>   2 files changed, 59 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
> index 0497b721136a..7570dbf22cdd 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
> @@ -427,6 +427,8 @@ void brcmf_fw_nvram_free(void *nvram)
>   struct brcmf_fw {
>   	struct device *dev;
>   	struct brcmf_fw_request *req;
> +	const char *alt_paths[BRCMF_FW_MAX_ALT_PATHS];
> +	int alt_index;
>   	u32 curpos;
>   	void (*done)(struct device *dev, int err, struct brcmf_fw_request *req);
>   };
> @@ -592,14 +594,18 @@ static int brcmf_fw_complete_request(const struct firmware *fw,
>   	return (cur->flags & BRCMF_FW_REQF_OPTIONAL) ? 0 : ret;
>   }
>   
> -static char *brcm_alt_fw_path(const char *path, const char *board_type)
> +static int brcm_alt_fw_paths(const char *path, const char *board_type,
> +			     const char *alt_paths[BRCMF_FW_MAX_ALT_PATHS])
>   {
>   	char alt_path[BRCMF_FW_NAME_LEN];
>   	const char *suffix;
>   
> +	memset(alt_paths, 0, array_size(sizeof(*alt_paths),
> +					BRCMF_FW_MAX_ALT_PATHS));
> +
>   	suffix = strrchr(path, '.');
>   	if (!suffix || suffix == path)
> -		return NULL;
> +		return -EINVAL;
>   
>   	/* strip extension at the end */
>   	strscpy(alt_path, path, BRCMF_FW_NAME_LEN);
> @@ -609,7 +615,18 @@ static char *brcm_alt_fw_path(const char *path, const char *board_type)
>   	strlcat(alt_path, board_type, BRCMF_FW_NAME_LEN);
>   	strlcat(alt_path, suffix, BRCMF_FW_NAME_LEN);
>   
> -	return kstrdup(alt_path, GFP_KERNEL);
> +	alt_paths[0] = kstrdup(alt_path, GFP_KERNEL);
> +
> +	return 0;
> +}
> +
> +static void
> +brcm_free_alt_fw_paths(const char *alt_paths[BRCMF_FW_MAX_ALT_PATHS])
> +{
> +	unsigned int i;
> +
> +	for (i = 0; alt_paths[i]; i++)
> +		kfree(alt_paths[i]);
>   }
>   
>   static int brcmf_fw_request_firmware(const struct firmware **fw,
> @@ -617,19 +634,25 @@ static int brcmf_fw_request_firmware(const struct firmware **fw,
>   {
>   	struct brcmf_fw_item *cur = &fwctx->req->items[fwctx->curpos];
>   	int ret;
> +	unsigned int i;
>   
>   	/* Files can be board-specific, first try a board-specific path */
>   	if (fwctx->req->board_type) {
> -		char *alt_path;
> +		const char *alt_paths[BRCMF_FW_MAX_ALT_PATHS];
>   
> -		alt_path = brcm_alt_fw_path(cur->path, fwctx->req->board_type);
> -		if (!alt_path)
> +		if (brcm_alt_fw_paths(cur->path, fwctx->req->board_type,
> +				      alt_paths) != 0)
>   			goto fallback;
>   
> -		ret = request_firmware(fw, alt_path, fwctx->dev);
> -		kfree(alt_path);
> -		if (ret == 0)
> -			return ret;
> +		for (i = 0; i < BRCMF_FW_MAX_ALT_PATHS && alt_paths[i]; i++) {
> +			ret = firmware_request_nowarn(fw, alt_paths[i],
> +						      fwctx->dev);
> +			if (ret == 0) {
> +				brcm_free_alt_fw_paths(alt_paths);
> +				return ret;
> +			}
> +		}
> +		brcm_free_alt_fw_paths(alt_paths);
>   	}
>   
>   fallback:
> @@ -641,6 +664,8 @@ static void brcmf_fw_request_done(const struct firmware *fw, void *ctx)
>   	struct brcmf_fw *fwctx = ctx;
>   	int ret;
>   
> +	brcm_free_alt_fw_paths(fwctx->alt_paths);
> +
>   	ret = brcmf_fw_complete_request(fw, fwctx);
>   
>   	while (ret == 0 && ++fwctx->curpos < fwctx->req->n_items) {
> @@ -662,13 +687,27 @@ static void brcmf_fw_request_done_alt_path(const struct firmware *fw, void *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)
> +	if (fw) {
> +		brcmf_fw_request_done(fw, ctx);
> +		return;
> +	}
> +
> +	fwctx->alt_index++;
> +	if (fwctx->alt_index < BRCMF_FW_MAX_ALT_PATHS &&
> +	    fwctx->alt_paths[fwctx->alt_index]) {
> +		/* Try the next alt firmware */
> +		ret = request_firmware_nowait(THIS_MODULE, true,
> +					      fwctx->alt_paths[fwctx->alt_index],
> +					      fwctx->dev, GFP_KERNEL, fwctx,
> +					      brcmf_fw_request_done_alt_path);
> +	} else {
> +		/* Fall back to canonical path if board firmware not found */
>   		ret = request_firmware_nowait(THIS_MODULE, true, first->path,
>   					      fwctx->dev, GFP_KERNEL, fwctx,
>   					      brcmf_fw_request_done);
> +	}
>   
> -	if (fw || ret < 0)
> +	if (ret < 0)
>   		brcmf_fw_request_done(fw, ctx);
>   }
>   
> @@ -693,7 +732,6 @@ int brcmf_fw_get_firmwares(struct device *dev, struct brcmf_fw_request *req,
>   {
>   	struct brcmf_fw_item *first = &req->items[0];
>   	struct brcmf_fw *fwctx;
> -	char *alt_path;
>   	int ret;
>   
>   	brcmf_dbg(TRACE, "enter: dev=%s\n", dev_name(dev));
> @@ -712,12 +750,13 @@ int brcmf_fw_get_firmwares(struct device *dev, struct brcmf_fw_request *req,
>   	fwctx->done = fw_cb;
>   
>   	/* First try alternative board-specific path if any */
> -	alt_path = brcm_alt_fw_path(first->path, fwctx->req->board_type);
> -	if (alt_path) {
> -		ret = request_firmware_nowait(THIS_MODULE, true, alt_path,
> +	if (brcm_alt_fw_paths(first->path, req->board_type,
> +			      fwctx->alt_paths) == 0) {
> +		fwctx->alt_index = 0;
> +		ret = request_firmware_nowait(THIS_MODULE, true,
> +					      fwctx->alt_paths[0],
>   					      fwctx->dev, GFP_KERNEL, fwctx,
>   					      brcmf_fw_request_done_alt_path);
> -		kfree(alt_path);
>   	} else {
>   		ret = request_firmware_nowait(THIS_MODULE, true, first->path,
>   					      fwctx->dev, GFP_KERNEL, fwctx,
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.h b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.h
> index e290dec9c53d..7f4e6e359c82 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.h
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.h
> @@ -11,6 +11,8 @@
>   
>   #define BRCMF_FW_DEFAULT_PATH		"brcm/"
>   
> +#define BRCMF_FW_MAX_ALT_PATHS	8
> +

Any motivation to have 8 here today? In patch #9 I see a list of 6 paths 
in the commit message so you need 6 and rounded up here to power of 2?

>   /**
>    * struct brcmf_firmware_mapping - Used to map chipid/revmask to firmware
>    *	filename and nvram filename. Each bus type implementation should create

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