Message-ID: <7137d4a9-6830-959d-1222-e63f5f618859@denx.de>
Date:   Thu, 16 Dec 2021 11:15:22 +0100
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Subject: Re: [PATCH 4/4] mmc: mmci: add hs200 support for stm32 sdmmc
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To:     Yann Gautier <yann.gautier@foss.st.com>
References: <20211215141727.4901-1-yann.gautier@foss.st.com>
 <20211215141727.4901-5-yann.gautier@foss.st.com>
 <c4528bc5-a826-a4ed-c4d6-e0ab84651ea2@denx.de>
 <b7ef5887-ce9e-9ba1-5819-765e68104cc5@foss.st.com>
Cc:     Ulf Hansson <ulf.hansson@linaro.org>,
        Russell King <linux@armlinux.org.uk>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Linus Walleij <linus.walleij@linaro.org>,
        Vladimir Zapolskiy <vz@mleia.com>,
        u.kleine-koenig@pengutronix.de,
        Christophe Kerello <christophe.kerello@foss.st.com>,
        Ludovic Barre <ludovic.barre@foss.st.com>,
        linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org
From:   Marek Vasut <marex@denx.de>
In-Reply-To: <b7ef5887-ce9e-9ba1-5819-765e68104cc5@foss.st.com>
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On 12/16/21 10:44, Yann Gautier wrote:
> On 12/16/21 10:14 AM, Marek Vasut wrote:
>> On 12/15/21 15:17, Yann Gautier wrote:
>>> Use feedback clock for HS200 mode, as for SDR104.
>>> The HS200 mode can be enabled through DT by using mmc-hs200-1_8v.
>>> It is possible to use it on STM32MP13, but not STM32MP15 platforms.
>>
>> HS200 is possible even on the MP15, it just doesn't yield any 
>> (performance) benefits due to the slower bus clock (125 MHz or so?), 
>> so it isn't worth enabling it on MP15. It is nice to see MP13 can do 
>> better.
> 
> Hi Marek,
> 
> There is a limitation on MP15, please see errata sheet [1], chapter 2.3.19.
> HS200 (and SDR104) shouldn't be enabled on MP15.
> 
> Best regards,
> Yann
> 
> [1] https://www.st.com/resource/en/errata_sheet/dm00516256.pdf

Oh, I see, so I was lucky to even ever get it working at all.

Thanks for the info.