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Subject: Re: [PATCH v4 5/9] ARM: imx_v6_v7_defconfig: build imx sdma driver as
 module
To:     Marcel Ziswiler <marcel.ziswiler@toradex.com>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>
Cc:     "linux@armlinux.org.uk" <linux@armlinux.org.uk>,
        "andreas@kemnade.info" <andreas@kemnade.info>,
        "festevam@gmail.com" <festevam@gmail.com>,
        "kernel@pengutronix.de" <kernel@pengutronix.de>,
        "s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
        "linux-imx@nxp.com" <linux-imx@nxp.com>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>,
        "pzimmermann@dh-electronics.com" <pzimmermann@dh-electronics.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20210920144938.314588-1-marcel@ziswiler.com>
 <20210920144938.314588-6-marcel@ziswiler.com>
 <dc987232-8687-a3cc-cc44-9e82e94ddd52@denx.de>
 <b399f461991b3dc6ba3d3332a054e7feea1d37f1.camel@toradex.com>
From:   Marek Vasut <marex@denx.de>
Message-ID: <f4d57f8e-2c84-0abb-7031-1f878eb28c08@denx.de>
Date:   Mon, 20 Sep 2021 18:14:54 +0200
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On 9/20/21 5:55 PM, Marcel Ziswiler wrote:
> On Mon, 2021-09-20 at 16:52 +0200, Marek Vasut wrote:
>> On 9/20/21 4:49 PM, Marcel Ziswiler wrote:
>>> From: Marcel Ziswiler <marcel.ziswiler@toradex.com>
>>>
>>> Build CONFIG_IMX_SDMA as a module to avoid the following boot issue:
>>>
>>> [    5.214751] imx-sdma 20ec000.sdma: Direct firmware load for
>>>    imx/sdma/sdma-imx6q.bin failed with error -2
>>> [    5.215762] imx-sdma 20ec000.sdma: Falling back to sysfs fallback
>>>    for: imx/sdma/sdma-imx6q.bin
>>
>> Isn't there some ROM-side SDMA firmware baked into the MX6 which is used
>> as a fallback if loading newer one from filesystem fails ? I suspect the
>> default ROM firmware might be buggy.
> 
> I'm not so sure about this. At least it seems to fail if no external firmware can be loaded.

See e.g. SDMA chapter in MX6SDLRM or similar, it does talk about 4k boot 
ROM, which contains scripts and utilities later referenced by scripts in 
RAM. It might be worth looking into that a bit further, but that seems 
like a separate topic from this patch.