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SubjectRe: [RFC 1/2] firmware class: Add stream_firmware API.
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hi Luis,


On 3/27/2017 2:36 PM, Luis R. Rodriguez wrote:
> On Thu, Mar 09, 2017 at 06:18:09PM -0600, yi1.li@linux.intel.com wrote:
>> From: Yi Li <yi1.li@linux.intel.com>
>>
>> Add function to load firmware in multiple chucks instead of
>>
>> loading the whole big firmware file at once.
>>
>> Signed-off-by: Yi Li <yi1.li@linux.intel.com>
>> ---
>> drivers/base/firmware_class.c | 128 ++++++++++++++++++++++++++++++++++++++++++
>> include/linux/firmware.h | 2 +
>> 2 files changed, 130 insertions(+)
>>
>> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
>> index ac350c5..44fddff 100644
>> --- a/drivers/base/firmware_class.c
>> +++ b/drivers/base/firmware_class.c
>> @@ -436,6 +436,62 @@ fw_get_filesystem_firmware(struct device *device, struct firmware_buf *buf)
>> return rc;
>> }
>>
>> +static int
>> +fw_stream_filesystem_firmware(struct device *device, struct firmware_buf *buf,
>> + size_t offset, size_t length)
>> +{
>> + int i, len;
>> + char *path;
>> + int rc = 0;
>> + struct file *file;
>> +
>> + buf->size = 0;
>> +
>> + path = __getname();
>> + if (!path)
>> + return -ENOMEM;
>> +
>> + for (i = 0; i < ARRAY_SIZE(fw_path); i++) {
>> + /* skip the unset customized path */
>> + if (!fw_path[i][0])
>> + continue;
>> +
>> + len = snprintf(path, PATH_MAX, "%s/%s",
>> + fw_path[i], buf->fw_id);
>> + if (len >= PATH_MAX) {
>> + rc = -ENAMETOOLONG;
>> + break;
>> + }
>> +
>> + if (!path || !*path)
>> + continue;
>> +
>> + if (!buf->data) {
>> + buf->data = vmalloc(length);
>> + if (!buf->data) {
>> + rc = -ENOMEM;
>> + break;
>> + }
>> + }
>> +
>> + file = filp_open(path, O_RDONLY, 0);
>> + if (IS_ERR(file))
>> + continue;
>> +
>> + buf->size = kernel_read(file, offset, (char *) buf->data,
>> + length);
>> + fput(file);
>> + break;
>> + }
>> +
>> + __putname(path);
>> +
>> + if (rc)
>> + dev_err(device, "loading %s failed with error %d\n",
>> + path, rc);
>> + return rc;
>> +}
> Yet another API call to read files form the fs seems rather odd, are you sure
> nothing can be done to re-purpose the existing call ?

Agree, I also hated to duplicate the read files from fs, what we are
missing in existing API is an "offset", which will enable loading the
firmware in pieces.

>
>> +
>> +EXPORT_SYMBOL(stream_firmware);
> New functionality should be EXPORT_SYMBOL_GPL().

Got it.

>
>> diff --git a/include/linux/firmware.h b/include/linux/firmware.h
>> index b1f9f0c..accd7f6 100644
>> --- a/include/linux/firmware.h
>> +++ b/include/linux/firmware.h
>> @@ -41,6 +41,8 @@ struct builtin_fw {
>> #if defined(CONFIG_FW_LOADER) || (defined(CONFIG_FW_LOADER_MODULE) && defined(MODULE))
>> int request_firmware(const struct firmware **fw, const char *name,
>> struct device *device);
>> +int stream_firmware(const struct firmware **fw, const char *name,
>> + struct device *device, size_t offset, size_t length);
> Have you looked at the rather new request_firmware_into_buf() ? I hated that
> as it did not get any proper code *review* but its there now... If we can
> leverage off of it to give us something useful for actual upstream drivers
> rather than cruft outside of the kernel I'd be a bit happier.

Yes, I looked request_firmware_into_buf API, it still load the whole
firmware image into a big memory buffer (but allocated outside of
firmware class).

>
> Also, please note that I had been noting we keep extending the firmware API
> with loose APIs, I've been consolidating a bit of this into a newer API which
> provides a flexible API for us. Since this is not upstream I don't expect
> you to work off of that, but I will Cc you on some updated patches which
> will fold in this work, I am expecting that the API we will ultimately use for
> this feature you are preoposing could be folded there.
>
> So for now, please consider the review notes above, and we can later see how
> we fold this into a new set of APIs which I hope to bake this week.

Cool, copy me on the updated patches. I am also working on the patch
based on Alan Tull's comments. Pardon me if I am slow this 2 weeks due
to family emergency.

>
> Luis
> --
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