linux-kernel - Re: [PATCH] usb: dwc2: hcd: Fix host channel halt flow

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Date:   Thu, 7 Dec 2017 18:14:44 +0100
From:   Stefan Wahren <stefan.wahren@...e.com>
To:     Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
Cc:     John Youn <John.Youn@...opsys.com>,
        Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: dwc2: hcd: Fix host channel halt flow

Hi Minas,

Am 07.12.2017 um 18:08 schrieb Stefan Wahren:
> According databook in Buffer and External DMA mode
> non-split periodic channels can't be halted.

do you know of any consequences not having this patch applied?

>
> Signed-off-by: Minas Harutyunyan <hminas@...opsys.com>

Please add a fixes tag.

Thanks
Stefan

> ---
>  drivers/usb/dwc2/hcd.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>
> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
> index 614bb9603def..987122497408 100644
> --- a/drivers/usb/dwc2/hcd.c
> +++ b/drivers/usb/dwc2/hcd.c
> @@ -985,6 +985,25 @@ void dwc2_hc_halt(struct dwc2_hsotg *hsotg, struct dwc2_host_chan *chan,
>  
>  	if (dbg_hc(chan))
>  		dev_vdbg(hsotg->dev, "%s()\n", __func__);
> +
> +	/*
> +	 * In buffer DMA or external DMA mode channel can't be halted
> +	 * for non-split periodic channels. At the end of the next
> +	 * uframe/frame (in the worst case), the core generates a channel
> +	 * halted and disables the channel automatically.
> +	 */
> +	if ((hsotg->core_params->dma_enable > 0 &&
> +	     hsotg->core_params->dma_desc_enable <= 0) ||
> +	     hsotg->hw_params.arch == GHWCFG2_EXT_DMA_ARCH) {
> +		if (!chan->do_split &&
> +		    (chan->ep_type == USB_ENDPOINT_XFER_ISOC ||
> +		     chan->ep_type == USB_ENDPOINT_XFER_INT)) {
> +			dev_err(hsotg->dev, "%s() Channel can't be halted\n",
> +				__func__);
> +			return;
> +		}
> +	}
> +
>  	if (halt_status == DWC2_HC_XFER_NO_HALT_STATUS)
>  		dev_err(hsotg->dev, "!!! halt_status = %d !!!\n", halt_status);
>