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Date:   Tue, 5 Dec 2023 16:37:06 +0800
From:   Shawn Guo <shawnguo@kernel.org>
To:     Nathan Rossi <nathan@nathanrossi.com>
Cc:     devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, Nathan Rossi <nathan.rossi@digi.com>,
        Fabio Estevam <festevam@gmail.com>, Li Jun <jun.li@nxp.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        NXP Linux Team <linux-imx@nxp.com>
Subject: Re: [PATCH v2] arm64: dts: imx8mp: imx8mq: Add
 parkmode-disable-ss-quirk on DWC3
Message-ID: <20231205083706.GC236001@dragon>
References: <20231106021436.1917894-1-nathan@nathanrossi.com>
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On Mon, Nov 06, 2023 at 02:14:36AM +0000, Nathan Rossi wrote:
> From: Nathan Rossi <nathan.rossi@digi.com>
> 
> The i.MX8MP and i.MX8MQ devices both use the same DWC3 controller and
> are both affected by a known issue with the controller due to specific
> behaviour when park mode is enabled in SuperSpeed host mode operation.
> 
> Under heavy USB traffic from multiple endpoints the controller will
> sometimes incorrectly process transactions such that some transactions
> are lost, or the controller may hang when processing transactions. When
> the controller hangs it does not recover.
> 
> This issue is documented partially within the linux-imx vendor kernel
> which references a Synopsys STAR number 9001415732 in commits [1] and
> additional details in [2]. Those commits provide some additional
> controller internal implementation specifics around the incorrect
> behaviour of the SuperSpeed host controller operation when park mode is
> enabled.
> 
> The summary of this issue is that the host controller can incorrectly
> enter/exit park mode such that part of the controller is in a state
> which behaves as if in park mode even though it is not. In this state
> the controller incorrectly calculates the number of TRBs available which
> results in incorrect access of the internal caches causing the overwrite
> of pending requests in the cache which should have been processed but
> are ignored. This can cause the controller to drop the requests or hang
> waiting for the pending state of the dropped requests.
> 
> The workaround for this issue is to disable park mode for SuperSpeed
> operation of the controller through the GUCTL1[17] bit. This is already
> available as a quirk for the DWC3 controller and can be enabled via the
> 'snps,parkmode-disable-ss-quirk' device tree property.
> 
> It is possible to replicate this failure on an i.MX8MP EVK with a USB
> Hub connecting 4 SuperSpeed USB flash drives. Performing continuous
> small read operations (dd if=/dev/sd... of=/dev/null bs=16) on the block
> devices will result in device errors initially and will eventually
> result in the controller hanging.
> 
>   [13240.896936] xhci-hcd xhci-hcd.0.auto: WARN Event TRB for slot 4 ep 2 with no TDs queued?
>   [13240.990708] usb 2-1.3: reset SuperSpeed USB device number 5 using xhci-hcd
>   [13241.015582] sd 2:0:0:0: [sdc] tag#0 UNKNOWN(0x2003) Result: hostbyte=0x07 driverbyte=DRIVER_OK cmd_age=0s
>   [13241.025198] sd 2:0:0:0: [sdc] tag#0 CDB: opcode=0x28 28 00 00 00 03 e0 00 01 00 00
>   [13241.032949] I/O error, dev sdc, sector 992 op 0x0:(READ) flags 0x80700 phys_seg 25 prio class 2
>   [13272.150710] usb 2-1.2: reset SuperSpeed USB device number 4 using xhci-hcd
>   [13272.175469] sd 1:0:0:0: [sdb] tag#0 UNKNOWN(0x2003) Result: hostbyte=0x03 driverbyte=DRIVER_OK cmd_age=31s
>   [13272.185365] sd 1:0:0:0: [sdb] tag#0 CDB: opcode=0x28 28 00 00 00 03 e0 00 01 00 00
>   [13272.193385] I/O error, dev sdb, sector 992 op 0x0:(READ) flags 0x80700 phys_seg 18 prio class 2
>   [13434.846556] xhci-hcd xhci-hcd.0.auto: xHCI host not responding to stop endpoint command
>   [13434.854592] xhci-hcd xhci-hcd.0.auto: xHCI host controller not responding, assume dead
>   [13434.862553] xhci-hcd xhci-hcd.0.auto: HC died; cleaning up
> 
> [1] https://github.com/nxp-imx/linux-imx/commit/97a5349d936b08cf301730b59e4e8855283f815c
> [2] https://github.com/nxp-imx/linux-imx/commit/b4b5cbc5a12d7c3b920d1d7cba0ada3379e4e42b
> 
> Fixes: fb8587a2c165 ("arm64: dtsi: imx8mp: add usb nodes")
> Fixes: ad37549cb5dc ("arm64: dts: imx8mq: add USB nodes")
> Signed-off-by: Nathan Rossi <nathan.rossi@digi.com>
> Reviewed-by: Fabio Estevam <festevam@gmail.com>

Applied, thanks!