Re: [PATCH v3] USB: ehci: reopen solution for Synopsys HC bug

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On 2020/6/8 11:46, Longfang Liu Wrote:
> A Synopsys USB2.0 core used in Huawei Kunpeng920 SoC has a bug which
> might cause the host controller not issuing ping.
>
> Bug description:
> After indicating an Interrupt on Async Advance, the software uses the
> doorbell mechanism to delete the Next Link queue head of the last
> executed queue head. At this time, the host controller still references
> the removed queue head(the queue head is NULL). NULL reference causes
> the host controller to lose the USB device.
>
> Solution:
> After deleting the Next Link queue head, when has_synopsys_hc_bug set
> to 1,the software can write one of the valid queue head addresses to
> the ASYNCLISTADDR register to allow the host controller to get
> the valid queue head. in order to solve that problem, this patch set
> the flag for Huawei Kunpeng920
>
> There are detailed instructions and solutions in this patch:
> commit 2f7ac6c19997 ("USB: ehci: add workaround for Synopsys HC bug")
>
> Signed-off-by: Longfang Liu <liulongfang@xxxxxxxxxx>
> ---
>
> Changes in v3:
> - updated comment message
>
> Changes in v2:
> - Added comment message
>
>  drivers/usb/host/ehci-pci.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
> index 1a48ab1..7ff2cbd 100644
> --- a/drivers/usb/host/ehci-pci.c
> +++ b/drivers/usb/host/ehci-pci.c
> @@ -216,6 +216,13 @@ static int ehci_pci_setup(struct usb_hcd *hcd)
>  		ehci_info(ehci, "applying MosChip frame-index workaround\n");
>  		ehci->frame_index_bug = 1;
>  		break;
> +	case PCI_VENDOR_ID_HUAWEI:
> +		/* Synopsys HC bug */
> +		if (pdev->device == 0xa239) {
> +			ehci_info(ehci, "applying Synopsys HC workaround\n");
> +			ehci->has_synopsys_hc_bug = 1;
> +		}
> +		break;
>  	}
>  
>  	/* optional debug port, normally in the first BAR */

Hi ALL,

 I'd appreciate any comments on this patch
from USB related people.

Thanks,

Longfang





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