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Subject: Re: [PATCH] ARM: dts: rockchip: remove cap-mmc-highspeed property
 from mk808 &mmc0 node
To:     Robin Murphy <robin.murphy@arm.com>, heiko@sntech.de
Cc:     robh+dt@kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-rockchip@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, paweljarosz3691@gmail.com
References: <20210820131920.1831-1-jbx6244@gmail.com>
 <bf6cba99-da3b-a6fe-4e4b-f4ea6e3c6e63@arm.com>
From:   Johan Jonker <jbx6244@gmail.com>
Message-ID: <c52b4cf0-d018-f6b4-8728-41551b8bf62b@gmail.com>
Date:   Fri, 20 Aug 2021 16:41:32 +0200
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On 8/20/21 4:17 PM, Robin Murphy wrote:
> On 2021-08-20 14:19, Johan Jonker wrote:
>> On the MK808 only a microSD slot is connected with the SDMMC Host
>> Controller,
>> so remove the cap-mmc-highspeed property from the &mmc0 node.
> 
> Why, does it do any harm? 

Harm not. Example rk3066 u-boot:

>>>>sd_select_mode_and_width
sd card: widths [4, 1, ] modes [MMC legacy, SD High Speed (50MHz), UHS
SDR12 (25MHz), UHS SDR25 (50MHz), ]
host: widths [4, 1, ] modes [MMC legacy, MMC High Speed (26MHz), SD
High Speed (50MHz), MMC High Speed (52MHz), ]
trying mode SD High Speed (50MHz) width 4 (at 50 MHz)

I would say only advertise host capabilities that are under normal
circumstances occur. How realistic is it to use a TF/Micro SD TO SD Card
Extension Cable Adapter (giggle) for a deprecated mmc card?

Johan

It's perfectly possible to connect a
> full-sized card to a microSD slot with an adapter. I came across my old
> SDIO WiFi card a while back and tried it that way for a giggle, but
> unfortunately it turned out not to be a chipset supported by any
> upstream driver.
> 
> Robin.
> 
>> Signed-off-by: Johan Jonker <jbx6244@gmail.com>
>> ---
>>   arch/arm/boot/dts/rk3066a-mk808.dts | 1 -
>>   1 file changed, 1 deletion(-)
>>
>> diff --git a/arch/arm/boot/dts/rk3066a-mk808.dts
>> b/arch/arm/boot/dts/rk3066a-mk808.dts
>> index 9790bc63b..b67f5cb51 100644
>> --- a/arch/arm/boot/dts/rk3066a-mk808.dts
>> +++ b/arch/arm/boot/dts/rk3066a-mk808.dts
>> @@ -123,7 +123,6 @@
>>     &mmc0 {
>>       bus-width = <4>;
>> -    cap-mmc-highspeed;
>>       cap-sd-highspeed;
>>       vmmc-supply = <&vcc_sd>;
>>       status = "okay";
>>