linux-kernel - Re: [PATCH 1/2] driver core: firmware loader: don't cache FW_ACTION

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Date:	Mon, 27 May 2013 18:10:28 +0530
From:	anish singh <anish198519851985@...il.com>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	Ming Lei <ming.lei@...onical.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel-mail <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] driver core: firmware loader: don't cache
 FW_ACTION_NOHOTPLUG firmware

On Mon, May 27, 2013 at 5:53 PM, Takashi Iwai <tiwai@...e.de> wrote:
> At Mon, 27 May 2013 17:26:22 +0530,
> anish singh wrote:
>>
>> On Mon, May 27, 2013 at 4:00 PM, Ming Lei <ming.lei@...onical.com> wrote:
>> > Generally there are only two drivers which don't need uevent to
>> > handle firmware loading, so don't cache these firmwares during
Sorry but it confuses me further,
If driver doesn't have information about these firmware then how
does it cache it?
>> Sorry but this statement confuses me i.e. "drivers which don't need
>> uevent to handle firmware loading". Does this mean that driver is
>> dependent on uevent to load the firmware?
>
> No.
>
>> or does this mean
>> that driver generates uevent to userspace and userpace in turn
>> provides the firmware?
>
> No.
>
> The userspace doesn't require uevent, and the driver doesn't generate
> uevent, either.  The userspace just loads the file when ready.
> See Documentation/dell_rbu.txt for example.  (And yes, it's a bad
> design.)
>
>
> Takashi
>
>> > suspend for these drivers since doing that may block firmware
>> > loading forever.
>> Explanation about why would it block would really help me or
>> for that matter anyone who reads this commit. Or may be
>> a url which discussed this problem.
>> >
>> > Both the two drivers are involved in private firmware images, so
>> > they don't hit in direct loading too.
>> >
>> > Cc: Takashi Iwai <tiwai@...e.de>
>> > Signed-off-by: Ming Lei <ming.lei@...onical.com>
>> > ---
>> >  drivers/base/firmware_class.c |    9 ++++++---
>> >  1 file changed, 6 insertions(+), 3 deletions(-)
>> >
>> > diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
>> > index e650c25..64e7870 100644
>> > --- a/drivers/base/firmware_class.c
>> > +++ b/drivers/base/firmware_class.c
>> > @@ -993,7 +993,8 @@ _request_firmware_prepare(struct firmware **firmware_p, const char *name,
>> >         return 1; /* need to load */
>> >  }
>> >
>> > -static int assign_firmware_buf(struct firmware *fw, struct device *device)
>> > +static int assign_firmware_buf(struct firmware *fw, struct device *device,
>> > +                               bool skip_cache)
>> >  {
>> >         struct firmware_buf *buf = fw->priv;
>> >
>> > @@ -1010,7 +1011,7 @@ static int assign_firmware_buf(struct firmware *fw, struct device *device)
>> >          * device may has been deleted already, but the problem
>> >          * should be fixed in devres or driver core.
>> >          */
>> > -       if (device)
>> > +       if (device && !skip_cache)
>> >                 fw_add_devm_name(device, buf->fw_id);
>> >
>> >         /*
>> > @@ -1066,8 +1067,10 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
>> >         if (!fw_get_filesystem_firmware(device, fw->priv))
>> >                 ret = fw_load_from_user_helper(fw, name, device,
>> >                                                uevent, nowait, timeout);
>> > +
>> > +       /* don't cache firmware handled without uevent */
>> >         if (!ret)
>> > -               ret = assign_firmware_buf(fw, device);
>> > +               ret = assign_firmware_buf(fw, device, !uevent);
>> >
>> >         usermodehelper_read_unlock();
>> >
>> > --
>> > 1.7.9.5
>> >
>> > --
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>>
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