Messages in this thread | | | Date | Sat, 29 Aug 2015 10:50:22 +0200 | From | Arend van Spriel <> | Subject | Re: Problems loading firmware using built-in drivers with kernels that use initramfs. |
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On 08/29/2015 09:11 AM, Takashi Iwai wrote: > On Sat, 29 Aug 2015 06:09:01 +0200, > Ming Lei wrote: >> >> On Sat, Aug 29, 2015 at 9:11 AM, Luis R. Rodriguez <mcgrof@suse.com> wrote: >>> On Thu, Aug 27, 2015 at 08:55:13AM +0800, Ming Lei wrote: >>>> On Thu, Aug 27, 2015 at 2:07 AM, Linus Torvalds >>>> <torvalds@linux-foundation.org> wrote: >>>>> On Wed, Aug 26, 2015 at 1:06 AM, Liam Girdwood >>>>> <liam.r.girdwood@linux.intel.com> wrote: >>>>>> >>>>>> I think the options are to either :- >>>>>> >>>>>> 1) Don not support audio DSP drivers using topology data as built-in >>>>>> drivers. Audio is not really a critical system required for booting >>>>>> anyway. >>>>> >>>>> Yes, forcing it to be a module and not letting people compile it in by >>>>> mistake (and then not have it work) is an option. >>>>> >>>>> That said, there are situations where people don't want to use >>>>> modules. I used to eschew them for security reasons, for example - now >>>>> I instead just do a one-time temporary key. But others may have other >>>>> reasons to try to avoid modules. >>>>> >>>>>> 2) Create a default PCM for every driver that has topology data on the >>>>>> assumption that every sound card will at least 1 PCM. This PCM can then >>>>>> be re-configured when the FW is loaded. >>>>> >>>>> That would seem to be the better option if it is reasonably implementable. >>>>> >>>>> Of course, some kind of timer-based retry (limited *somehow*) of the >>>>> fw loading could work too, but smells really really hacky. >>>> >>>> Yeah, years ago, we discussed to use -EPROBE_DEFER for the situation, >>>> which should be one kind of fix, but looks there were objections at that time. >>> >>> That would still be a hack. I'll note there is also asynchronous probe support >>> now but to use that would also be a hack for this issue. We don't want to >> >> If we think firmware as one kind of resources like regulators, gpio and others, >> PROBE_DEFER is one good match for firmware loading case, and >> it has been used by lots of drivers, so why can't it be used for >> firmware loading? >> >> One problem is that we need to convert drivers into returning -EPROBE_DEFER >> in case of request failure, and that may involve some work, but which >> should be mechanical. > > I find such a delaying mechanism not so bad, too. It's very > straightforward, at least, no big pain in the transition in the driver > side.
Not sure how this is going to work with request_firmware_nowait(). We use that in our drivers to get rid of ~60 sec. delay in probe and consequently boot time when built-in. So basically we return 0 on probe lacking better knowledge. Guess we can always move back to request_firmware calls when defer_probe support is available.
Regards, Arend
>>> encourage folks to go down that road. They'd be hacks for this issue as you >>> are simply delaying the driver probe for a later time and there is no guarantee >>> that any pivot_root() might have already been completed later to ensure your >>> driver's fw file is present. So it may work or it may not. >> >> We can trigger defer probe explicitly once root fs is setup or other condition >> is met. > > Right, how to trigger the reprobe (and relevant optimization) needs to > be considered on top of the current mechanism. > > > Takashi > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
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