linux-kernel - Re: [PATCH v5 3/3] mmc: host: meson-mx-sdhc: new driver for the Amlogic Meson SDHC host

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Date:   Wed, 22 Apr 2020 23:47:21 +0530
From:   Anand Moon <linux.amoon@...il.com>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     linux-amlogic@...ts.infradead.org,
        devicetree <devicetree@...r.kernel.org>,
        linux-mmc@...r.kernel.org, Ulf Hansson <ulf.hansson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, jianxin.pan@...ogic.com,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        yinxin_1989@...yun.com,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        lnykww@...il.com
Subject: Re: [PATCH v5 3/3] mmc: host: meson-mx-sdhc: new driver for the
 Amlogic Meson SDHC host

Hi Martin,

On Sat, 28 Mar 2020 at 06:04, Martin Blumenstingl
<martin.blumenstingl@...glemail.com> wrote:
>
> The SDHC MMC host controller on Amlogic SoCs provides an eMMC and MMC
> card interface with 1/4/8-bit bus width.
> It supports eMMC spec 4.4x/4.5x including HS200 (up to 100MHz clock).
>
> The public S805 datasheet [0] contains a short documentation about the
> registers. Unfortunately it does not describe how to use the registers
> to make the hardware work. Thus this driver is based on reading (and
> understanding) the Amlogic 3.10 GPL kernel code.
>
> Some hardware details are not easy to see. Jianxin Pan was kind enough
> to answer my questions:
> The hardware has built-in busy timeout support. The maximum timeout is
> 30 seconds. This is only documented in Amlogic's internal
> documentation.
>
> The controller only works with very specific clock configurations. The
> details are not part of the public datasheet. In my own words the
> supported configurations are:
> - 399.812kHz:   clkin =  850MHz div = 2126 sd_rx_phase = 63
> - 1MHz:         clkin =  850MHz div = 850  sd_rx_phase = 55
> - 5.986MHz:     clkin =  850MHz div = 142  sd_rx_phase = 24
> - 25MHz:        clkin =  850MHz div = 34   sd_rx_phase = 15
> - 47.222MHz:    clkin =  850MHz div = 18   sd_rx_phase = 11/15 (SDR50/HS)
> - 53.125MHz:    clkin =  850MHz div = 16   sd_rx_phase = (tuning)
> - 70.833MHz:    clkin =  850MHz div = 12   sd_rx_phase = (tuning)
> - 85MHz:        clkin =  850MHz div = 10   sd_rx_phase = (tuning)
> - 94.44MHz:     clkin =  850MHz div = 9    sd_rx_phase = (tuning)
> - 106.25MHz:    clkin =  850MHz div = 8    sd_rx_phase = (tuning)
> - 127.5MHz:     clkin = 1275MHz div = 10   sd_rx_phase = (tuning)
> - 141.667MHz:   clkin =  850MHz div = 6    sd_rx_phase = (tuning)
> - 159.375MHz:   clkin = 1275MHz div = 8    sd_rx_phase = (tuning)
> - 212.5MHz:     clkin = 1275MHz div = 6    sd_rx_phase = (tuning)
> - (sd_tx_phase is always 1, 94.44MHz is not listed in the datasheet
>    but this is what the 3.10 BSP kernel on Odroid-C1 actually uses)
>
> NOTE: CMD23 support is disabled for now because it results in command
> timeouts and thus decreases read performance.
>
> Tested-by: Wei Wang <lnykww@...il.com>
> Tested-by: Xin Yin <yinxin_1989@...yun.com>
> Reviewed-by: Xin Yin <yinxin_1989@...yun.com>
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
> ---

Please add my tested on Odroid C1+

Tested-by: Anand Moon <linux.amoon@...il.com>

Best Regards
-Anand