Re: [PATCH v2] Revert "usb: dwc3: core: Enable AutoRetry feature in the controller"

[Jakub Vaněk]

Hi Thinh,

On Wed, 2023-07-12 at 22:55 +0000, Thinh Nguyen wrote:
> On Thu, Jul 13, 2023, Jakub Vanek wrote:
> > This reverts commit b138e23d3dff90c0494925b4c1874227b81bddf7.
> > 
> > AutoRetry has been found to cause some issues. This feature allows
> > the controller in host mode (further referred to as the xHC) to
> > send
> > non-terminating/burst retry ACKs (Retry=1 and Nump!=0) instead of
> > terminating retry ACKs (Retry=1 and Nump=0) to devices when
> > a transaction error occurs.
> > 
> > Unfortunately, some USB devices fail to retry transactions when
> > the xHC sends them a burst retry ACK. When this happens, the xHC
> 
> For some clarity: if the device continues to respond with CRC error,
> the xHC will not complete endpoint related commands while it keeps
> autoretry.

Acknowledged. Do you think it it would be better to respin this patch
once more to include this in the changelog?

> > enters a strange state. After the affected transfer times out,
> > the xHCI driver tries to resume normal operation of the xHC
> > by sending it a Stop Endpoint command. However, the xHC fails
> > to respond to it, and the xHCI driver gives up. [1]
> > This fact is reported via dmesg:
> > 
> > [sda] tag#29 uas_eh_abort_handler 0 uas-tag 1 inflight: CMD IN
> > [sda] tag#29 CDB: opcode=0x28 28 00 00 69 42 80 00 00 48 00
> > xhci-hcd: xHCI host not responding to stop endpoint command
> > xhci-hcd: xHCI host controller not responding, assume dead
> > xhci-hcd: HC died; cleaning up
> > 
> > Some users observed this problem on an Odroid HC2 with the JMS578
> > USB3-to-SATA bridge. The issue can be triggered by starting
> > a read-heavy workload on an attached SSD. After a while, the host
> > controller would die and the SSD would disappear from the system.
> > [1]
> > 
> > Further analysis by Synopsys determined that controller revisions
> > other than the one in Odroid HC2 are also affected by this.
> > The recommended solution was to disable AutoRetry altogether.
> > This change does not have a noticeable performance impact. [2]
> > 
> > Fixes: b138e23d3dff ("usb: dwc3: core: Enable AutoRetry feature in
> > the controller")
> > Link:
> > https://urldefense.com/v3/__https://lore.kernel.org/r/a21f34c04632d250cd0a78c7c6f4a1c9c7a43142.camel@xxxxxxxxx/__;!!A4F2R9G_pg!aCe0isNmX63t6ILE2Tv2cX4UnrpDFo6LXWb6oS3-OYFYfX88igrfqmW4Z8UdO7sWz0mdco6vbBrR_KMzYaccpLF7Kw$
> >   [1]
> > Link:
> > https://urldefense.com/v3/__https://lore.kernel.org/r/20230711214834.kyr6ulync32d4ktk@xxxxxxxxxxxx/__;!!A4F2R9G_pg!aCe0isNmX63t6ILE2Tv2cX4UnrpDFo6LXWb6oS3-OYFYfX88igrfqmW4Z8UdO7sWz0mdco6vbBrR_KMzYae75T8GCw$
> >   [2]
> > Cc: stable@xxxxxxxxxxxxxxx
> > Cc: Mauro Ribeiro <mauro.ribeiro@xxxxxxxxxxxxxx>
> > Cc: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
> > Suggested-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
> > Signed-off-by: Jakub Vanek <linuxtardis@xxxxxxxxx>
> > ---
> > V1 -> V2: Updated to disable AutoRetry everywhere based on Synopsys
> > feedback
> >           Reworded the changelog a bit to make it clearer
> > 
> >  drivers/usb/dwc3/core.c | 16 ----------------
> >  drivers/usb/dwc3/core.h |  3 ---
> >  2 files changed, 19 deletions(-)
> > 
> > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > index f6689b731718..a4e079d37566 100644
> > --- a/drivers/usb/dwc3/core.c
> > +++ b/drivers/usb/dwc3/core.c
> > @@ -1209,22 +1209,6 @@ static int dwc3_core_init(struct dwc3 *dwc)
> >                 dwc3_writel(dwc->regs, DWC3_GUCTL1, reg);
> >         }
> >  
> > -       if (dwc->dr_mode == USB_DR_MODE_HOST ||
> > -           dwc->dr_mode == USB_DR_MODE_OTG) {
> > -               reg = dwc3_readl(dwc->regs, DWC3_GUCTL);
> > -
> > -               /*
> > -                * Enable Auto retry Feature to make the controller
> > operating in
> > -                * Host mode on seeing transaction errors(CRC
> > errors or internal
> > -                * overrun scenerios) on IN transfers to reply to
> > the device
> > -                * with a non-terminating retry ACK (i.e, an ACK
> > transcation
> > -                * packet with Retry=1 & Nump != 0)
> > -                */
> > -               reg |= DWC3_GUCTL_HSTINAUTORETRY;
> > -
> > -               dwc3_writel(dwc->regs, DWC3_GUCTL, reg);
> > -       }
> > -
> >         /*
> >          * Must config both number of packets and max burst
> > settings to enable
> >          * RX and/or TX threshold.
> > diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> > index 8b1295e4dcdd..a69ac67d89fe 100644
> > --- a/drivers/usb/dwc3/core.h
> > +++ b/drivers/usb/dwc3/core.h
> > @@ -256,9 +256,6 @@
> >  #define DWC3_GCTL_GBLHIBERNATIONEN     BIT(1)
> >  #define DWC3_GCTL_DSBLCLKGTNG          BIT(0)
> >  
> > -/* Global User Control Register */
> > -#define DWC3_GUCTL_HSTINAUTORETRY      BIT(14)
> > -
> >  /* Global User Control 1 Register */
> >  #define DWC3_GUCTL1_DEV_DECOUPLE_L1L2_EVT      BIT(31)
> >  #define DWC3_GUCTL1_TX_IPGAP_LINECHECK_DIS     BIT(28)
> > -- 
> > 2.25.1
> > 
> 
> Acked-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>

Thanks!


> Thanks,
> Thinh

Best regards,
Jakub