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Date:   Tue, 24 Oct 2023 15:27:30 +0200
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     "Arnd Bergmann" <arnd@kernel.org>,
        "Martin Tuma" <martin.tuma@digiteqautomotive.com>,
        "Mauro Carvalho Chehab" <mchehab@kernel.org>,
        "Hans Verkuil" <hverkuil-cisco@xs4all.nl>,
        dmaengine@vger.kernel.org, "Lizhi Hou" <lizhi.hou@amd.com>,
        "Brian Xu" <brian.xu@amd.com>,
        "Raj Kumar Rampelli" <raj.kumar.rampelli@amd.com>,
        "Vinod Koul" <vkoul@kernel.org>
Cc:     linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] media: pci: mgb4: remove bogus 'select' statements
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On Mon, Oct 23, 2023, at 18:05, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> As this is just a regular device driver, it has no business force-enabling
> other drivers in the system, it should be entirely independent of the
> implementation of the spi-nor layer or the specific DMA engine.
>
> The IIO symbols that are selected here are library modules that
> are legitimately used.
>
> Fixes: 0ab13674a9bd ("media: pci: mgb4: Added Digiteq Automotive MGB4 driver")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/media/pci/mgb4/Kconfig | 4 ----
>  1 file changed, 4 deletions(-)
>
> diff --git a/drivers/media/pci/mgb4/Kconfig b/drivers/media/pci/mgb4/Kconfig
> index f2a05a1c8ffa..b90347c7f19b 100644
> --- a/drivers/media/pci/mgb4/Kconfig
> +++ b/drivers/media/pci/mgb4/Kconfig
> @@ -6,10 +6,6 @@ config VIDEO_MGB4
>  	select VIDEOBUF2_DMA_SG
>  	select IIO_BUFFER
>  	select IIO_TRIGGERED_BUFFER
> -	select I2C_XILINX
> -	select SPI_XILINX
> -	select MTD_SPI_NOR
> -	select XILINX_XDMA

Apparently, the XDMA reference was in fact needed, as MGB4
calls some exported symbols from that particular dmaengine
driver:

aarch64-linux-ld: drivers/media/pci/mgb4/mgb4_core.o: in function `init_i2c': mgb4_core.c:(.text+0x3ec): undefined reference to `xdma_get_user_irq'
aarch64-linux-ld: mgb4_core.c:(.text+0x404): undefined reference to `xdma_enable_user_irq'

I couldn't easily figure out what a 'user_irq' is here,
but I wonder if this is the expected way to use the DMA engine
layer. Maybe this should have been a nested irqchip instead,
or it should be encoded in the DMA request specifier?

     Arnd