linux-kernel - Re: [PATCH v1 3/4] firmware loader: allow distribution to choose default search paths

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Date:	Thu, 6 Jun 2013 12:47:50 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Ming Lei <ming.lei@...onical.com>
Cc:	linux-kernel@...r.kernel.org, Takashi Iwai <tiwai@...e.de>
Subject: Re: [PATCH v1 3/4] firmware loader: allow distribution to choose
 default search paths

On Thu, Jun 06, 2013 at 08:01:49PM +0800, Ming Lei wrote:
> For some distributions(e.g. android), firmware images aren't put
> under kernel built-in search paths, so introduce one Kconfig
> option to allow distributions or users to choose its specific default
> search paths, which are always tried before searching from kernel
> built-in paths in direct loading.
> 
> Also this patch introduces fw_get_fw_file_from_paths to cover all
> search paths, and fw_get_filesystem_firmware is simpified a bit.
> 
> Cc: Takashi Iwai <tiwai@...e.de>
> Signed-off-by: Ming Lei <ming.lei@...onical.com>
> ---
>  drivers/base/Kconfig          |   14 ++++++++++
>  drivers/base/firmware_class.c |   61 ++++++++++++++++++++++++++++++++++-------
>  2 files changed, 65 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
> index 07abd9d..2be10e4 100644
> --- a/drivers/base/Kconfig
> +++ b/drivers/base/Kconfig
> @@ -156,6 +156,20 @@ config FW_LOADER_USER_HELPER
>  	  no longer required unless you have a special firmware file that
>  	  resides in a non-standard path.
>  
> +config FW_CUSTOMIZED_PATH
> +	string "default firmware search paths for direct loading"
> +	help
> +	  On some distribution(e.g. android), firmware images aren't
> +	  put under kernel built-in search paths, so provide this option
> +	  for distributions to choose a distribution specific firmware
> +	  search path. The option allows to choose more than one path,
> +	  and paths are seperated with colon like $PATH(e.g. on android,
> +	  the option might look as "/etc/firmware:/vendor/firmware").
> +	  Each path should be a absolute path, and relative path will be
> +	  ignored.
> +
> +	  If you are unsure about this, don't choose here.
> +
>  config DEBUG_DRIVER
>  	bool "Driver Core verbose debug messages"
>  	depends on DEBUG_KERNEL
> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> index 6ede229..051db83 100644
> --- a/drivers/base/firmware_class.c
> +++ b/drivers/base/firmware_class.c
> @@ -265,8 +265,13 @@ static void fw_free_buf(struct firmware_buf *buf)
>  
>  /* direct firmware loading support */
>  static char fw_path_para[256];
> +
> +/* search runtime paths first, then static pre-defined paths */
>  static const char * const fw_path[] = {
>  	fw_path_para,
> +#ifdef CONFIG_FW_CUSTOMIZED_PATH
> +	CONFIG_FW_CUSTOMIZED_PATH,
> +#endif
>  	"/lib/firmware/updates/" UTS_RELEASE,
>  	"/lib/firmware/updates",
>  	"/lib/firmware/" UTS_RELEASE,
> @@ -314,6 +319,50 @@ static bool fw_read_file_contents(struct file *file, struct firmware_buf *fw_buf
>  	return true;
>  }
>  
> +static bool fw_get_file_firmware(const char *path,
> +				 struct firmware_buf *buf)
> +{
> +	struct file *file;
> +	bool success;
> +
> +	file = filp_open(path, O_RDONLY, 0);
> +	if (IS_ERR(file))
> +		return false;
> +	success = fw_read_file_contents(file, buf);
> +	fput(file);
> +
> +	return success;
> +}
> +
> +/* The path in @paths is seperated by ';' */

No it isn't.

> +static bool fw_get_file_fw_from_paths(const char *paths, char *path,
> +				      struct firmware_buf *buf)
> +{
> +	int len, start, end = -1;
> +	char *pos;
> +
> +	do {
> +		start = end + 1;
> +		pos = strchr(&paths[start], ':');

As you have an array of paths now, why are you doing the ':' check
still?  Don't do that, just allow the person building the kernel to add
one path to the loader, that should be all that we need, right?

thanks,

greg k-h
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