Re: arm64: dts: rockchip: Disable HS400 for mmc on rk3399-roc-pc

From: Doug Anderson <dianders@chromium.org>
To: "Heiko Stübner" <heiko@sntech.de>
Cc: Markus Reichl <m.reichl@fivetechno.de>,
	Mark Rutland <mark.rutland@arm.com>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	Brian Norris <briannorris@chromium.org>,
	Tony Xie <tony.xie@rock-chips.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Shawn Lin <shawn.lin@rock-chips.com>,
	Jeffy Chen <jeffy.chen@rock-chips.com>,
	"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Vicente Bergas <vicencb@gmail.com>,
	"open list:ARM/Rockchip SoC..."
	<linux-rockchip@lists.infradead.org>,
	Rob Herring <robh+dt@kernel.org>,
	Klaus Goger <klaus.goger@theobroma-systems.com>,
	Enric Balletbo i Serra <enric.balletbo@collabora.com>,
	Philipp Tomsich <philipp.tomsich@theobroma-systems.com>,
	Randy Li <ayaka@soulik.info>,
	Kishon Vijay Abraham I <kishon@ti.com>,
	Ezequiel Garcia <ezequiel@collabora.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Christoph Muellner <christoph.muellner@theobroma-systems.com>
Subject: Re: arm64: dts: rockchip: Disable HS400 for mmc on rk3399-roc-pc
Date: Mon, 18 Nov 2019 08:08:37 -0800	[thread overview]
Message-ID: <CAD=FV=VnjyQJpRcW6P1f4+ZrSOzAe2Cnoej=it4aCz+F_ozukw@mail.gmail.com> (raw)
In-Reply-To: <3460135.SDF8zhHPq4@diego>

Hi,

On Fri, Nov 15, 2019 at 3:19 AM Heiko Stübner <heiko@sntech.de> wrote:
>
> Hi Markus,
>
> Am Freitag, 15. November 2019, 11:37:58 CET schrieb Markus Reichl:
> > Am 14.11.19 um 14:10 schrieb Heiko Stuebner:
> > > $subject is missing the [PATCH] prefix
> > will fix.
>
> no need to resend just for this ... just to keep in mind for future patches ;-)
>
>
> > > Am Montag, 11. November 2019, 10:51:04 CET schrieb Markus Reichl:
> > >> Working with rootfs on two 128GB mmcs on rk3399-roc-pc.
> > >>
> > >> One (mmc name 128G72, one screw hole) works fine in HS400 mode.
> > >> Other (mmc name DJNB4R, firefly on pcb, two screw holes) gets lots of
> > >> mmc1: "running CQE recovery", even hangs with damaged fs,
> > >> when running under heavy load, e.g. compiling kernel.
> > >> Both run fine with HS200.
> > >>
> > >> Disabling CQ with patch mmc: core: Add MMC Command Queue Support kernel parameter [0] did not help.
> > >> [0] https://gitlab.com/ayufan-repos/rock64/linux-mainline-kernel/commit/54e264154b87dfe32a8359b2726e2d5611adbaf3
> > >
> > > I'm hoping for some input from other people in Cc but your mail headers
> > > also referenced the drive-impendance series from Christoph [0], which
> > > it seems we need to poke the phy maintainer again.
> > >
> > > Did you check if changing the impedance helped (like the signal dampening
> > > Philipp described in one of the replies there).
> >
> > checked with
> >
> > &emmc_phy {
> > +       drive-impedance-ohm = <33>;
> >
> > gives no improvement:
>
> That is sad ... I guess we really should disable hs400 then ...
> that may give others more incentive to dive deeper ;-)

Just out of curiosity, is the problem with the strobe line, or with
hs400?  Have you tried using the solution from "rk3399-gru.dtsi"?
Namely:

        /*
         * Signal integrity isn't great at 200 MHz and 150 MHz (DDR) gives the
         * same (or nearly the same) performance for all eMMC that are intended
         * to be used.
         */
        assigned-clock-rates = <150000000>;

IIRC hs400 on rk3399 was a bit iffy but running at 150 MHz made it
much more reliable and still gave you 300 MB/s transfer rate (so much
better than hs200).  In reality many eMMC chips can't do > 300 MB/s
anyway.

-Doug