Re: [PATCH v3 3/3] arm64: dts: rockchip: Disable DCMDs on RK3399's eMMC controller.

From: Heiko Stuebner <heiko@sntech.de>
To: Ulf Hansson <ulf.hansson@linaro.org>,
	Klaus Goger <klaus.goger@theobroma-systems.com>
Cc: Christoph Muellner <christoph.muellner@theobroma-systems.com>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Shawn Lin <shawn.lin@rock-chips.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Philipp Tomsich <philipp.tomsich@theobroma-systems.com>,
	Michal Simek <michal.simek@xilinx.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Douglas Anderson <dianders@chromium.org>,
	Jeffy Chen <jeffy.chen@rock-chips.com>,
	Lin Huang <hl@rock-chips.com>, Randy Li <ayaka@soulik.info>,
	Tony Xie <tony.xie@rock-chips.com>,
	"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	DTML <devicetree@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.or>
Subject: Re: [PATCH v3 3/3] arm64: dts: rockchip: Disable DCMDs on RK3399's eMMC controller.
Date: Wed, 27 Mar 2019 13:21:31 +0100	[thread overview]
Message-ID: <1591627.dSi6EvuFCI@phil> (raw)
In-Reply-To: <CAPDyKFpPh7TZqRfUX7x52aUeY69-i3NSo5XtuwTjN8yHqdAVDw@mail.gmail.com>

Am Montag, 25. März 2019, 14:27:26 CET schrieb Ulf Hansson:
> On Fri, 22 Mar 2019 at 12:39, Christoph Muellner
> <christoph.muellner@theobroma-systems.com> wrote:
> >
> > When using direct commands (DCMDs) on an RK3399, we get spurious
> > CQE completion interrupts for the DCMD transaction slot (#31):
> >
> > [  931.196520] ------------[ cut here ]------------
> > [  931.201702] mmc1: cqhci: spurious TCN for tag 31
> > [  931.206906] WARNING: CPU: 0 PID: 1433 at /usr/src/kernel/drivers/mmc/host/cqhci.c:725 cqhci_irq+0x2e4/0x490
> > [  931.206909] Modules linked in:
> > [  931.206918] CPU: 0 PID: 1433 Comm: irq/29-mmc1 Not tainted 4.19.8-rt6-funkadelic #1
> > [  931.206920] Hardware name: Theobroma Systems RK3399-Q7 SoM (DT)
> > [  931.206924] pstate: 40000005 (nZcv daif -PAN -UAO)
> > [  931.206927] pc : cqhci_irq+0x2e4/0x490
> > [  931.206931] lr : cqhci_irq+0x2e4/0x490
> > [  931.206933] sp : ffff00000e54bc80
> > [  931.206934] x29: ffff00000e54bc80 x28: 0000000000000000
> > [  931.206939] x27: 0000000000000001 x26: ffff000008f217e8
> > [  931.206944] x25: ffff8000f02ef030 x24: ffff0000091417b0
> > [  931.206948] x23: ffff0000090aa000 x22: ffff8000f008b000
> > [  931.206953] x21: 0000000000000002 x20: 000000000000001f
> > [  931.206957] x19: ffff8000f02ef018 x18: ffffffffffffffff
> > [  931.206961] x17: 0000000000000000 x16: 0000000000000000
> > [  931.206966] x15: ffff0000090aa6c8 x14: 0720072007200720
> > [  931.206970] x13: 0720072007200720 x12: 0720072007200720
> > [  931.206975] x11: 0720072007200720 x10: 0720072007200720
> > [  931.206980] x9 : 0720072007200720 x8 : 0720072007200720
> > [  931.206984] x7 : 0720073107330720 x6 : 00000000000005a0
> > [  931.206988] x5 : ffff00000860d4b0 x4 : 0000000000000000
> > [  931.206993] x3 : 0000000000000001 x2 : 0000000000000001
> > [  931.206997] x1 : 1bde3a91b0d4d900 x0 : 0000000000000000
> > [  931.207001] Call trace:
> > [  931.207005]  cqhci_irq+0x2e4/0x490
> > [  931.207009]  sdhci_arasan_cqhci_irq+0x5c/0x90
> > [  931.207013]  sdhci_irq+0x98/0x930
> > [  931.207019]  irq_forced_thread_fn+0x2c/0xa0
> > [  931.207023]  irq_thread+0x114/0x1c0
> > [  931.207027]  kthread+0x128/0x130
> > [  931.207032]  ret_from_fork+0x10/0x20
> > [  931.207035] ---[ end trace 0000000000000002 ]---
> >
> > The driver shows this message only for the first spurious interrupt
> > by using WARN_ONCE(). Changing this to WARN() shows, that this is
> > happening quite frequently (up to once a second).
> >
> > Since the eMMC 5.1 specification, where CQE and CQHCI are specified,
> > does not mention that spurious TCN interrupts for DCMDs can be simply
> > ignored, we must assume that using this feature is not working reliably.
> >
> > The current implementation uses DCMD for REQ_OP_FLUSH only, and
> > I could not see any performance/power impact when disabling
> > this optional feature for RK3399.
> >
> > Therefore this patch disables DCMDs for RK3399.
> >
> > Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
> > Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
> 
> FYI, I leave this for arm-soc to pick up.

I've duplicated your fixes+stable tags and applied for 5.2

Thanks
Heiko