Message-ID: <eafd8d8c0cbcaca1b190f84ec17a1dcd7aec0306.camel@collabora.com>
Date: Tue, 27 Feb 2024 10:38:22 +0000
From: Christopher Obbard <chris.obbard@...labora.com>
To: Folker Schwesinger <dev@...ker-schwesinger.de>, Alban Browaeys
 <alban.browaeys@...il.com>, Doug Anderson <dianders@...omium.org>, Jensen
 Huang <jensenhuang@...endlyarm.com>
Cc: Heiko Stübner <heiko@...ech.de>, Rob Herring
 <robh+dt@...nel.org>, Krzysztof Kozlowski
 <krzysztof.kozlowski+dt@...aro.org>,  Vinod Koul <vkoul@...nel.org>, Chris
 Ruehl <chris.ruehl@...ys.com.hk>, Brian Norris <briannorris@...omium.org>,
 "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
 <devicetree@...r.kernel.org>, Linux ARM
 <linux-arm-kernel@...ts.infradead.org>, "open list:ARM/Rockchip SoC..."
 <linux-rockchip@...ts.infradead.org>, LKML <linux-kernel@...r.kernel.org>,
 Kishon Vijay Abraham I <kishon@...nel.org>
Subject: Re: [PATCH] arm64: dts: rockchip: add enable-strobe-pulldown to
 emmc phy on rk3399

Hi,

On Tue, 2024-02-27 at 10:11 +0000, Folker Schwesinger wrote:
> Hi,
> 
> On Tue Feb 27, 2024 at 3:05 AM CET, Alban Browaeys wrote:
> > Le mercredi 24 août 2022 à 07:57 -0700, Doug Anderson a écrit :
> > > On Tue, Aug 23, 2022 at 8:11 PM Jensen Huang
> > > <jensenhuang@...endlyarm.com> wrote:
> > > > I realized that only some devices may be affected, so I considered
> > > > modifying rk3399-nanopi4.dtsi only,
> > > > but other boards without external pull-down should still need this
> > > > patch.
> > > 
> > > I guess the other alternative would be to change how the dt property
> > > works. You could say:
> > > 
> > > 1. If `enable-strobe-pulldown` is set then enable the strobe
> > > pulldown.
> > > 
> > > 2. If `enable-strobe-pulldown` is not set then don't touch the pin in
> > > the kernel.
> > > 
> > > 3. If someone later needs to explicitly disable the strobe pulldown
> > > they could add a new property like `disable-strobe-pulldown`.
> > > 
> > > 
> > > Obviously there are tradeoffs between that and what you've done and
> > > I'm happy to let others make the call of which they'd prefer.
> > > 
> > 
> > Christopher could you try "ROCK Pi 4" and "ROCK Pi 4+" with 
> > "enable-strobe-pulldown" instead of disabling HS400 as you did in July
> > 2023?
> > 
> 
> with the following applied, the EMMC related errors are gone. dmesg only
> shows "Purging ... bytes" during my tests:
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4.dtsi
> b/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4.dtsi
> index f2279aa6ca9e..ae0fb87e1a8b 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3399-rock-pi-4.dtsi
> @@ -647,8 +647,10 @@ &saradc {
>  &sdhci {
>         max-frequency = <150000000>;
>         bus-width = <8>;
> -       mmc-hs200-1_8v;
> +       mmc-hs400-1_8v;
> +       mmc-hs400-enhanced-strobe;
>         non-removable;
> +       rockchip,enable-strobe-pulldown;
>         status = "okay";
>  };
> 
> For testing I ran dd three times in a row:
> 
> dd if=/dev/zero of=./zero.bin bs=1M count=5000
> 
> I tested this on both a Rock 4SE board and a Rock Pi 4B+ board with the
> same results.

Just for the record, all Rock 4 board schematics have no external strobe
pulldown resistor on the board, so we should be good to enable this.

I wonder what other boards this could be enabled for ?


It seemed to be the case on some eMMC it would work, others it wouldn't.

I haven't yet tested the above diff here as yet, but I can do that this week
on multiple boards & eMMC combos.

The diff above is also missing a fixes tag (and also be fixed for rk3399-rock-
4c-plus.dts).


> 
> > 
> > Could the behavior be reverted to let the vendor kernel default for the
> > default case (ie enable pulldown)?
> > 
> > 
> > 
> > 
> > I believe 99% of the boards are now broken with this new internal
> > pulldown behavior (all  these with internal pulldown). More on that
> > later but to sum up, nobody  complained because downstream kernels like
> > Armbian all disabled HS400 for all boards, at least for rk3399.
> > 
> > 
> > Do we really want to ask 99% of the board dts to add this "enable-
> > strobe-pulldown" in their dts?
> > Chris, was your custom board not working with the vender kernel default
> > to enable unconditionaly?
> > What was the rationale to  choose the opposite default from the vendor
> > kernel one?
> > 
> > 
> > As told in the commit that introduced this new behavior the default for
> > the vendor kernel was the opposite of what was introduced in the Linux
> > kernel:
> > "
> > https://github.com/torvalds/linux/commit/8b5c2b45b8f0a11c9072da0f7baf9ee986d3151e
> > 
> > commit 8b5c2b45b8f0a11c9072da0f7baf9ee986d3151e
> > Author: Chris Ruehl <chris.ruehl@...ys.com.hk>
> > Date:   Sun Nov 29 13:44:14 2020 +0800
> > 
> > phy: rockchip: set pulldown for strobe line in dts
> > 
> > This patch add support to set the internal pulldown via dt property
> > and allow simplify the board design for the trace from emmc-phy to
> > the eMMC chipset.
> > Default to not set the pull-down.
> > 
> > This patch was inspired from the 4.4 tree of the
> > Rockchip SDK, where it is enabled unconditional.
> > The patch had been tested with our rk3399 customized board.
> > "
> > 
> > 
> > 
> > For RK3588 I see this commit which makes me believe the internal
> > pulldown case is the most common "
> > commit 37f3d6108730713c411827ab4af764909f4dfc78
> > Author: Sam Edwards <cfsworks@...il.com>
> > Date:   Tue Dec 5 12:29:00 2023 -0800
> > 
> > 
> > arm64: dts: rockchip: Fix eMMC Data Strobe PD on rk3588
> > 
> > JEDEC standard JESD84-B51 defines the eMMC Data Strobe line, which is
> > currently used only in HS400 mode, as a device->host clock signal that
> > "is used only in read operation. The Data Strobe is always High-Z (not
> > driven by the device and pulled down by RDS) or Driven Low in write
> > operation, except during CRC status response." RDS is a pull-down
> > resistor specified in the 10K-100K ohm range. Thus per the standard,
> > the
> > Data Strobe is always pulled to ground (by the eMMC and/or RDS) during
> > write operations.
> > 
> > Evidently, the eMMC host controller in the RK3588 considers an active
> > voltage on the eMMC-DS line during a write to be an error.
> > 
> > The default (i.e. hardware reset, and Rockchip BSP) behavior for the
> > RK3588 is to activate the eMMC-DS pin's builtin pull-down. As a result,
> > many RK3588 board designers do not bother adding a dedicated RDS
> > resistor, instead relying on the RK3588's internal bias. The current
> > devicetree, however, disables this bias (`pcfg_pull_none`), breaking
> > HS400-mode writes for boards without a dedicated RDS, but with an eMMC
> > chip that chooses to High-Z (instead of drive-low) the eMMC-DS line.
> > (The Turing RK1 is one such board.)
> > 
> > Fix this by changing the bias in the (common) emmc_data_strobe case to
> > reflect the expected hardware/BSP behavior. This is unlikely to cause
> > regressions elsewhere: the pull-down is only relevant for High-Z eMMCs,
> > and if this is redundant with a (dedicated) RDS resistor, the effective
> > result is only a lower resistance to ground -- where the range of
> > tolerance is quite high. If it does, it's better fixed in the specific
> > devicetrees.
> > "
> > 
> > 
> > 
> > 
> > 
> > 
> > Lately two other upstream dts disabled HS400 due to this new behavior I
> > believe:
> > "
> > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/arch/arm64/boot/dts/rockchip?id=2bd1d2dd808c60532283e9cf05110bf1bf2f9079
> > author	Christopher Obbard <chris.obbard@...labora.com>	2023-
> > 07-05 15:42:55 +0100
> > committer	Heiko Stuebner <heiko@...ech.de>	2023-07-10
> > 15:43:24 +0200
> > commit	2bd1d2dd808c60532283e9cf05110bf1bf2f9079 (patch)
> > tree	57cbf7eaa91deb68f143577d5d1dbc0d9141480e
> > /arch/arm64/boot/dts/rockchip
> > parent	cee572756aa2cb46e959e9797ad4b730b78a050b (diff)
> > download	linux-2bd1d2dd808c60532283e9cf05110bf1bf2f9079.tar.gz
> > arm64: dts: rockchip: Disable HS400 for eMMC on ROCK 4C+
> > 
> > 
> > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/arch/arm64/boot/dts/rockchip?id=cee572756aa2cb46e959e9797ad4b730b78a050b
> > author	Christopher Obbard <chris.obbard@...labora.com>	2023-
> > 07-05 15:42:54 +0100
> > committer	Heiko Stuebner <heiko@...ech.de>	2023-07-10
> > 15:43:24 +0200
> > commit	cee572756aa2cb46e959e9797ad4b730b78a050b (patch)
> > tree	cf3ed8ff6230cbde04353503417c1a75ba15c249
> > /arch/arm64/boot/dts/rockchip
> > parent	5ce6971e5279c569defc2f2ac800692049bbaa90 (diff)
> > download	linux-cee572756aa2cb46e959e9797ad4b730b78a050b.tar.gz
> > arm64: dts: rockchip: Disable HS400 for eMMC on ROCK Pi 4
> > "
> > 
> > 
> > All Armbian RK3399 boards, as far as I know, had to disable HS400, I
> > also believe due to this commit.
> > 
> > You can also search google for "running cqe recovery rk3399 armbian".
> > 
> > 
> > This was never reported upstream though. But as HS400 is disabled
> > everywhere nobody notice the regression nowadays.
> > 
> > 
> > > 
> > > > BR,
> > > > Jensen
> > > > 
> > > > On Tue, Aug 23, 2022 at 10:13 PM Doug Anderson
> > > > <dianders@...omium.org> wrote:
> > > > > 
> > > > > Hi,
> > > > > 
> > > > > On Tue, Aug 23, 2022 at 4:53 AM Heiko Stübner <heiko@...ech.de>
> > > > > wrote:
> > > > > > 
> > > > > > Am Montag, 22. August 2022, 09:41:39 CEST schrieb Jensen Huang:
> > > > > > > Internal pull-down for strobe line (GRF_EMMCPHY_CON2[9]) was
> > > > > > > disabled
> > > > > > > by commit 8b5c2b45b8f0, which causes I/O error in HS400 mode.
> > > > > > > 
> > > > > > > Tested on NanoPC-T4.
> > > > > > > 
> > > > > > > Fixes: 8b5c2b45b8f0 ("phy: rockchip: set pulldown for strobe
> > > > > > > line in dts")
> > > > > > > Signed-off-by: Jensen Huang <jensenhuang@...endlyarm.com>
> > > > > > 
> > > > > > ok, so this looks like it restores previous functionality.
> > > > > > 
> > > > > > I'm just wondering as the "offending" patch is from 2020, why
> > > > > > this
> > > > > > only turns up now. Any ideas?
> > > > > 
> > 
> > Probbaly because the introduction of PROBE_DEFERRED in regulator core
> > before that (in 5.10.60) already broke at least my board HS400 due to
> > double init. Thus why it took me so long to see this new pulldown
> > behavior commit. I was testing every regulator core double init fixup
> > patchset while not understanding why reverting the PROBE_DEFERRED
> > commit on 5.10.60 worked but not on newer kernels (ie this new pulldown
> > behavior was introduced in 5.11...).
> > 
> > 
> > 
> > 
> > > > > Ah, I see. So before the offending patch we used to just leave
> > > > > the
> > > > > pull state at whatever the default was when the kernel was
> > > > > booted.
> > > > > After the offending patch we chose a default.
> > > > > 
> > > > > On kevin I see an external pull down on this line. Enabling both
> > > > > the
> > > > > internal and external is probably not a huge deal, it'll just
> > > > > affect
> > > > > the strength of the pull.
> > > > > 
> > > > > On bob I _think_ the external pull down is also stuffed.
> > > > > 
> > > > > ...so I guess that would explain why it didn't cause a problem
> > > > > for at
> > > > > least those two boards?
> > > > > 
> > > > > -Doug
> > 
> > 
> > In my opinion it is about these board already being broken by the
> > regulator core change, so nobody noticed the second regression. When
> > the first regression was fixed, it was very hard to correlate the still
> > broken behavior to the second regression.
> > 
> > 
> > I confirm that on Helios64, setting "enable-strobe-pulldown" fixes the
> > EMMC error I had when writing with HS400ES enabled:
> > mmc1: running CQE recovery 
> > mmc1: cqhci: spurious TCN for tag 12
> > 
> > It also took me so long to report upstream as my board code (rk3399-
> > kobol-helios64.dts) is not completely upstreamed yet so I use an
> > Armbian patched kernel.
> > 
> > 
> > 
> > Alban
> > 
> > 
> > 
> > _______________________________________________
> > Linux-rockchip mailing list
> > Linux-rockchip@...ts.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-rockchip
> 

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