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Subject: Re: [PATCH for-next] arm64: defconfig: Set bcm2835-dma as built-in
To:     Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
        Ulf Hansson <ulf.hansson@linaro.org>
CC:     <f.fainelli@gmail.com>, Catalin Marinas <catalin.marinas@arm.com>,
        <linux-kernel@vger.kernel.org>,
        <linux-rpi-kernel@lists.infradead.org>,
        Will Deacon <will@kernel.org>,
        <linux-arm-kernel@lists.infradead.org>
References: <C043QOCZ7SMB.2XXX2ESS1ZJ98@linux-9qgx>
From:   Peter Ujfalusi <peter.ujfalusi@ti.com>
Message-ID: <e29e23fd-cb60-56b9-e53d-ecbafc12bf8c@ti.com>
Date:   Fri, 24 Jan 2020 20:07:51 +0200
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Hi Nicolas,

On 1/24/20 4:47 PM, Nicolas Saenz Julienne wrote:
>> If you need MMC rootfs then the DMA needs to be built in or have initrd
>> with the modules.
>> The driver expects to have DMA channel and it is going to wait for it to
>> appear unless the request fails.
>>
>> Without moving the DMA as built in and removing the deferred probe
>> handling form the MMC driver, one can just remove the DMA support from
>> the mmc-bcm2835 as it is not used at all.
> 
> Oh sorry, I meant to ask if the 'Fixes:' tag was really needed.

Complements: or Needed-for: would be better, but with the Fixed tag this
patch would be picked in case the dma_request_chan() conversion patch
gets backported for stable.

> The
> patch itself is very much needed since not everyone uses initrds in the
> RPi world, and we want to keep being compatible as much as possible with
> older device-trees.

Sure. Just checked on my RPi with libreELEC that at least they have the
DMA built in, I assume other distros do the same.

It would be great if this patch would make it to linux-next as soon as
it is possible for sure.

>> I wonder why this is not signaled by automated boot testing, if any
>> exists for bcm2835>
> Actually now that you mention it, it's failing since today here:
> https://kernelci.org/boot/bcm2837-rpi-3-b/

Oh, so you can even have a bug report to back this patch ;)

- Peter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
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