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From: Takashi Iwai <tiwai@suse.de>
To: Scott Branden <scott.branden@broadcom.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	David Brown <david.brown@linaro.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Shuah Khan <shuah@kernel.org>,
	bjorn.andersson@linaro.org,
	Shuah Khan <skhan@linuxfoundation.org>,
	Arnd Bergmann <arnd@arndb.de>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
	linux-fsdevel@vger.kernel.org,
	BCM Kernel Feedback <bcm-kernel-feedback-list@broadcom.com>,
	Olof Johansson <olof@lixom.net>,
	Andrew Morton <akpm@linux-foundation.org>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	Colin Ian King <colin.king@canonical.com>,
	Kees Cook <keescook@chromium.org>,
	linux-kselftest@vger.kernel.org
Subject: Re: [PATCH 2/7] firmware: add offset to request_firmware_into_buf
Date: Mon, 26 Aug 2019 19:12:52 +0200
Message-ID: <s5ho90byhnv.wl-tiwai@suse.de> (raw)
In-Reply-To: <93b8285a-e5eb-d4a4-545d-426bbbeb8008@broadcom.com>

On Mon, 26 Aug 2019 17:41:40 +0200,
Scott Branden wrote:
> 
> HI Takashi,
> 
> On 2019-08-26 8:20 a.m., Takashi Iwai wrote:
> > On Fri, 23 Aug 2019 21:44:42 +0200,
> > Scott Branden wrote:
> >> Hi Takashi,
> >>
> >> Thanks for review.  comments below.
> >>
> >> On 2019-08-23 3:05 a.m., Takashi Iwai wrote:
> >>> On Thu, 22 Aug 2019 21:24:46 +0200,
> >>> Scott Branden wrote:
> >>>> Add offset to request_firmware_into_buf to allow for portions
> >>>> of firmware file to be read into a buffer.  Necessary where firmware
> >>>> needs to be loaded in portions from file in memory constrained systems.
> >>> AFAIU, this won't work with the fallback user helper, right?
> >> Seems to work fine in the fw_run_tests.sh with fallbacks.
> > But how?  You patch doesn't change anything about the fallback loading
> > mechanism.
> Correct - I didn't change any of the underlying mechanisms,
> so however request_firmware_into_buf worked before it still does.
> >   Or, if the expected behavior is to load the whole content
> > and then copy a part, what's the merit of this API?
> The merit of the API is that the entire file is not copied into a buffer.
> In my use case, the buffer is a memory region in PCIe space that isn't
> even large enough for the whole file.  So the only way to get the file
> is to read it
> in portions.

BTW: does the use case above mean that the firmware API directly
writes onto the given PCI iomem region?  If so, I'm not sure whether
it would work as expected on all architectures.  There must be a
reason of the presence of iomem-related API like memcpy_toio()...


thanks,

Takashi

  parent reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-22 19:24 [PATCH 0/7] firmware: add partial read support in request_firmware_into_buf Scott Branden
2019-08-22 19:24 ` [PATCH 1/7] fs: introduce kernel_pread_file* support Scott Branden
2019-08-23 12:29   ` Takashi Iwai
2019-08-23 19:55     ` Scott Branden
2019-08-23 21:29       ` Luis Chamberlain
2019-08-22 19:24 ` [PATCH 2/7] firmware: add offset to request_firmware_into_buf Scott Branden
2019-08-22 19:47   ` Luis Chamberlain
2019-08-22 20:07     ` Scott Branden
2019-08-22 21:12       ` Luis Chamberlain
2019-08-22 23:30         ` Scott Branden
2019-08-23 15:47           ` Luis Chamberlain
2019-08-23 20:16             ` Scott Branden
2019-08-23 10:05   ` Takashi Iwai
2019-08-23 19:44     ` Scott Branden
2019-08-26 15:20       ` Takashi Iwai
2019-08-26 15:41         ` Scott Branden
2019-08-26 15:57           ` Takashi Iwai
2019-08-26 17:12           ` Takashi Iwai [this message]
2019-08-26 17:24             ` Scott Branden
2019-08-27 10:40               ` Takashi Iwai
2019-10-11 13:31                 ` Luis Chamberlain
2019-08-22 19:24 ` [PATCH 3/7] test_firmware: add partial read support for request_firmware_into_buf Scott Branden
2019-08-22 19:24 ` [PATCH 4/7] selftests: firmware: Test partial file reads of request_firmware_into_buf Scott Branden
2019-08-22 19:24 ` [PATCH 5/7] bcm-vk: add bcm_vk UAPI Scott Branden
2019-08-27 13:54   ` Arnd Bergmann
2019-08-27 14:49   ` Kieran Bingham
2019-10-08 15:59     ` Olof Johansson
2019-08-22 19:24 ` [PATCH 6/7] misc: bcm-vk: add Broadcom Valkyrie driver Scott Branden
2019-08-27 14:14   ` Arnd Bergmann
2019-08-27 15:25     ` Nicolas Dufresne
2019-08-22 19:24 ` [PATCH 7/7] MAINTAINERS: bcm-vk: Add maintainer for Broadcom Valkyrie Driver Scott Branden

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