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References: <20220304135134.47827-1-yann.gautier@foss.st.com> <20220304135134.47827-2-yann.gautier@foss.st.com>
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From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Mon, 14 Mar 2022 23:43:22 +0100
Message-ID: <CACRpkdYQz+-im3n-r0_8RKL7so2bHS=aZobty4BbzixmPzms-Q@mail.gmail.com>
Subject: Re: [PATCH 1/3] dt-bindings: mmc: mmci: add a property to disable DMA LLI
To:     Yann Gautier <yann.gautier@foss.st.com>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, linux-mmc@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Christophe Kerello <christophe.kerello@foss.st.com>,
        Ludovic Barre <ludovic.barre@foss.st.com>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Russell King <linux@armlinux.org.uk>,
        Marek Vasut <marex@denx.de>, kernel@dh-electronics.com,
        Manivannan Sadhasivam <mani@kernel.org>,
        Grzegorz Szymaszek <gszymaszek@short.pl>
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"On Fri, Mar 4, 2022 at 2:52 PM Yann Gautier <yann.gautier@foss.st.com> wrote:

> On STMicroelectronics variant of PL18x, the DMA Linked Lists are supported
> starting from revision v2 of the peripheral. But it has limitations,
> as all the buffers should be aligned on block size (except the last one).
> But this cannot be guaranteed with SDIO. We should then have a property
> to disable the support of LLI.
>
> Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>

Actually I think this is present also on the ux500 variants. See:
commit 2253ed4b36dc876d1598c4dab5587e537ec68c34
"mmc: mmci: Support any block sizes for ux500v2 and qcom variant"

Spot the variant data "dma_power_of_2".

So whatever property you add
to the variant data (not in the device tree please) should
be added to the ux500 variants as well, it will *VERY* likely
have a problem with LLI elements not being a power of 2
as it is the ancestor of later STMicro variants.

It might actually be the reason for some annoying WiFi error
messages I have seen :/

Yours,
Linus Walleij