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

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Date:	Fri, 7 Jun 2013 09:24:25 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
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 Fri, Jun 7, 2013 at 3:47 AM, Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
> 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.

Will fix it.

>
>> +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?

The distribution may have put firmware under more than one places,
for example, android put firmwares under "/etc/firmware" and
"/vendor/firmware", so I am afraid that only allowing one path or two
paths isn't flexible enough.

Thanks,
--
Ming Lei
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