linux-kernel - Re: [RFC 1/2] firmware class: Add stream

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Date:   Mon, 20 Mar 2017 13:34:58 -0500
From:   Alan Tull <delicious.quinoa@...il.com>
To:     "Li, Yi" <yi1.li@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     ming.lei@...onical.com, mcgrof@...nel.org,
        atull <atull@...nsource.altera.com>,
        Moritz Fischer <moritz.fischer@...us.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-fpga@...r.kernel.org
Subject: Re: [RFC 1/2] firmware class: Add stream_firmware API.

On Mon, Mar 20, 2017 at 1:00 PM, Alan Tull <delicious.quinoa@...il.com> wrote:

>> +int
>> +stream_firmware(const struct firmware **firmware_p, const char *name,
>> +                struct device *device, size_t offset, size_t length)
>> +{
>> +       size_t ret;
>> +
>> +       /* Need to pin this module until return */
>> +       __module_get(THIS_MODULE);
>> +       ret = _stream_firmware(firmware_p, name, device, NULL, 0,
>> +                               FW_OPT_UEVENT | FW_OPT_NO_WARN, offset, length);

IIUC, here you are setting size == 0 and buf == NULL  to prevent
_request_firmware_prepare from attempting to load from built in
firmware.

So three of the parameters buf, size, and opt_flags are fixed and
don't need to be passed to _stream_firmware().

Alternatively, I wonder how hard it would be to code this so that the
streaming interface will fall back and successfully get the built in
or cached firmware if it exists and stream it out in PAGE_SIZE chunks.

Alan Tull