linux-kernel - Re: [PATCH] arm64: defconfig: Disable firmware sysfs fallback

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Message-ID: <CAA8EJpo8+iEWdJU35mFWu6Dzpu-j_4vmHktrg_8pJhS2=8nYtw@mail.gmail.com>
Date:   Fri, 1 Oct 2021 03:12:55 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Vinod Koul <vkoul@...nel.org>, Arnd Bergmann <arnd@...nel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <linux-arm-msm@...r.kernel.org>, Robin Gong <yibin.gong@....com>
Subject: Re: [PATCH] arm64: defconfig: Disable firmware sysfs fallback

On Fri, 1 Oct 2021 at 00:51, Bjorn Andersson <bjorn.andersson@...aro.org> wrote:
>
> Part of the enablement of SDMA on the IMX platforms, '7f4e4afa140c
> ("arm64: defconfig: Enable SDMA on i.mx8mq/8mm")' also enabled
> CONFIG_FW_LOADER_USER_HELPER_FALLBACK, to allow "firmware loaded by
> udev".
>
> Unfortunately having the fallback enabled does, due to the 60 second
> timeout, essentially requiring userspace to provide a firmware loader.
> But systemd dropped the support for this interface back in 2014 and
> because arm64 is the only architecture that has this enabled, there
> doesn't seem to be any standard solution available.

I tend to use the following 'standard' solution:

cat /lib/udev/rules.d/50-firmware.rules
# stub for immediately telling the kernel that userspace firmware loading
# failed; necessary to avoid long timeouts with CONFIG_FW_LOADER_USER_HELPER=y
SUBSYSTEM=="firmware", ACTION=="add", ATTR{loading}="-1"

> Examples of this problem can be found in e.g. the ath10k driver, which
> with a standard distro can take about 10 minutes before wlan0 appears.
>
> The alternative to this patch would be to change these drivers to use
> firmware_request_direct(), to avoid the sysfs fallback. But that would
> prevent other systems, such as Android, to rely on a userspace firmware
> loader to pick the firmware from a non-standard place, with just a
> custom defconfig.
>
> This patch therefor attempts to align the arm64 defconfig will all other
> architectures in the upstream kernel.
>
> Cc: Robin Gong <yibin.gong@....com>
> Cc: Shawn Guo <shawnguo@...nel.org>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

> ---
>  arch/arm64/configs/defconfig | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
> index da988a54bfb9..f9e0b3fdaf0b 100644
> --- a/arch/arm64/configs/defconfig
> +++ b/arch/arm64/configs/defconfig
> @@ -243,7 +243,6 @@ CONFIG_PCI_EPF_TEST=m
>  CONFIG_DEVTMPFS=y
>  CONFIG_DEVTMPFS_MOUNT=y
>  CONFIG_FW_LOADER_USER_HELPER=y
> -CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y
>  CONFIG_HISILICON_LPC=y
>  CONFIG_SIMPLE_PM_BUS=y
>  CONFIG_FSL_MC_BUS=y
> --
> 2.29.2
>


-- 
With best wishes
Dmitry