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From: "Luis R. Rodriguez" <mcgrof@kernel.org>
To: Martijn Coenen <maco@android.com>,
	Andy Gross <andy.gross@linaro.org>,
	David Brown <david.brown@linaro.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: dmitry.torokhov@gmail.com,
	"Matt Fleming" <matt@codeblueprint.co.uk>,
	"Will Deacon" <will.deacon@arm.com>,
	platform-driver-x86@vger.kernel.org,
	"David Howells" <dhowells@redhat.com>,
	"Peter Jones" <pjones@redhat.com>,
	"Luis R. Rodriguez" <mcgrof@kernel.org>,
	"H . Peter Anvin" <hpa@zytor.com>,
	"open list:ANDROID DRIVERS" <devel@driverdev.osuosl.org>,
	nbroeking@me.com, x86@kernel.org,
	"Arve Hjønnevåg" <arve@android.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Darren Hart" <dvhart@infradead.org>,
	"Mimi Zohar" <zohar@linux.vnet.ibm.com>,
	"Arend Van Spriel" <arend.vanspriel@broadcom.com>,
	"Todd Kjos" <tkjos@android.com>,
	"Kees Cook" <keescook@chromium.org>,
	linux-efi <linux-efi@vger.kernel.org>,
	linux-arm-msm@vger.kernel.org, "Torsten Duwe" <duwe@suse.de>,
	"Josh Triplett" <josh@joshtriplett.org>,
	"Chris Wright" <chrisw@sous-sol.org>,
	"Hans de Goede" <hdegoede@redhat.com>,
	"Andy Lutomirski" <luto@kernel.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Kalle Valo" <kvalo@codeaurora.org>,
	"Alan Cox" <alan@linux.intel.com>,
	mfuzzey@parkeon.com, "Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
	"Stephen Boyd" <sboyd@kernel.org>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Vikram Mulukutla" <markivx@codeaurora.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-security-module@vger.kernel.org,
	"Dave Olsthoorn" <dave@bewaar.me>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"Andy Shevchenko" <andy@infradead.org>
Subject: Re: [PATCH v3 2/5] efi: Add embedded peripheral firmware support
Date: Tue, 8 May 2018 15:38:05 +0000	[thread overview]
Message-ID: <20180508153805.GC27853@wotan.suse.de> (raw)
In-Reply-To: <CAB0TPYGnCu+anWHBGvkaigxD--8uHQaQJ2c62kegJ7mTqvkmnA@mail.gmail.com>

On Fri, May 04, 2018 at 12:44:37PM -0700, Martijn Coenen wrote:
> On Wed, Apr 25, 2018 at 10:55 AM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> > Android became the primary user of CONFIG_FW_LOADER_USER_HELPER_FALLBACK.
> >
> > It would be good for us to hear from Android folks if their current use of
> > request_firmware_into_buf() is designed in practice to *never* use the direct
> > filesystem firmware loading interface, and always rely instead on the
> > fallback mechanism.
> 
> It's hard to answer this question for Android in general. As far as I
> can tell the reasons we use CONFIG_FW_LOADER_USER_HELPER(_FALLBACK)
> are:
> 1) We have multiple different paths on our devices where firmware can
> be located, and the direct loader only supports one custom path
> 2) Most of those paths are not mounted by the time the corresponding
> drivers are loaded, because pretty much all Android kernels today are
> built without module support, and therefore drivers are loaded well
> before the firmware partition is mounted
> 3) I think we use _FALLBACK because doing this with uevents is just
> the easiest thing to do; our init code has a firmware helper that
> deals with this and searches the paths that we care about
> 
> 2) will change at some point, because Android is moving towards a
> model where device-specific peripheral drivers will be loaded as
> modules, and since those modules would likely come from the same
> partition as the firmware, it's possible that the direct load would
> succeed (depending on whether the custom path is configured there or
> not). But I don't think we can rely on the direct loader even in those
> cases, unless we could configure it with multiple custom paths.
> 
> I have no reason to believe request_firmware_into_buf() is special in
> this regard; drivers that depend on it may have their corresponding
> firmware in different locations, so just depending on the direct
> loader would not be good enough.

Thanks! This is very useful! This provides yet-another justification and use
case to document for the fallback mechanism. I'll go and extend it.

> >
> > Is ptr below
> >
> >         ret = request_firmware_into_buf(&seg_fw, fw_name, dev,
> >                                         ptr, phdr->p_filesz);
> >
> > Also part of the DMA buffer allocated earlier via:
> >
> >         ret = qcom_scm_pas_init_image(pas_id, fw->data, fw->size);
> >
> > Android folks?
> 
> I think the Qualcomm folks owning this (Andy, David, Bjorn, already
> cc'd here) are better suited to answer that question.

Andy, David, Bjorn?

  Luis
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  reply	other threads:[~2018-05-08 15:38 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-08 17:40 [PATCH v3 0/5] efi/firmware/platform-x86: Add EFI embedded fw support Hans de Goede
2018-04-08 17:40 ` [PATCH v3 1/5] efi: Export boot-services code and data as debugfs-blobs Hans de Goede
2018-04-16  8:23   ` Ard Biesheuvel
2018-04-24 13:11     ` Hans de Goede
2018-04-23 11:55   ` Greg Kroah-Hartman
2018-04-08 17:40 ` [PATCH v3 2/5] efi: Add embedded peripheral firmware support Hans de Goede
2018-04-16  8:28   ` Ard Biesheuvel
2018-04-24 13:17     ` Hans de Goede
2018-04-17  0:17   ` Luis R. Rodriguez
2018-04-17  8:58     ` Hans de Goede
2018-04-17  9:19     ` Hans de Goede
2018-04-23 21:11   ` Luis R. Rodriguez
2018-04-24 15:09     ` Hans de Goede
2018-04-24 16:07       ` Mimi Zohar
2018-04-24 18:33         ` Hans de Goede
2018-04-24 23:42         ` Luis R. Rodriguez
2018-04-25  5:00           ` Mimi Zohar
2018-04-25 17:55             ` Luis R. Rodriguez
2018-05-04  0:21               ` Luis R. Rodriguez
2018-05-04 15:26                 ` Martijn Coenen
2018-05-04 19:44               ` Martijn Coenen
2018-05-08 15:38                 ` Luis R. Rodriguez [this message]
2018-05-08 16:10                   ` Luis R. Rodriguez
2018-06-07 16:49                     ` Bjorn Andersson
2018-06-07 18:22                       ` Luis R. Rodriguez
2018-06-01 19:23                   ` Luis R. Rodriguez
2018-06-06 20:32                     ` Do Qualcomm drivers use DMA buffers for request_firmware_into_buf()? Luis R. Rodriguez
2018-06-07 16:18                       ` Bjorn Andersson
     [not found]                         ` <CAKv+Gu8+Fq7BD4XD-YCyXzZh0mg6Z2k-0styj0cw6_uZfaqy4Q@mail.gmail.com>
     [not found]                           ` <20180607163308.GA18834@kroah.com>
2018-06-08  6:41                             ` Vlastimil Babka
2018-06-07 16:33             ` [PATCH v3 2/5] efi: Add embedded peripheral firmware support Bjorn Andersson
2018-04-08 17:40 ` [PATCH v3 3/5] platform/x86: Rename silead_dmi to touchscreen_dmi Hans de Goede
2018-04-09  8:07   ` Andy Shevchenko
2018-04-20  0:20     ` Darren Hart
2018-04-08 17:40 ` [PATCH v3 4/5] platform/x86: touchscreen_dmi: Add EFI embedded firmware info support Hans de Goede
2018-04-08 17:40 ` [PATCH v3 5/5] platform/x86: touchscreen_dmi: Add info for the Chuwi Vi8 Plus tablet Hans de Goede
2018-04-09  8:10   ` Andy Shevchenko

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