linux-kernel - Re: [PATCH 1/2] usb: musb: Fix DMA for host mode

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Date:	Tue, 2 Feb 2016 16:24:13 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Joshua Henderson <joshua.henderson@...rochip.com>,
	linux-kernel@...r.kernel.org
Cc:	Cristian Birsan <cristian.birsan@...rochip.com>,
	Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org
Subject: Re: [PATCH 1/2] usb: musb: Fix DMA for host mode

Hello.

On 2/2/2016 3:37 AM, Joshua Henderson wrote:

> From: Cristian Birsan <cristian.birsan@...rochip.com>
>
> Commit ac33cdb166811223cc (usb: musb: Remove ifdefs for musb_host_rx in
> musb_host.c part5) introduces a problem setting DMA host mode.

    scripts/checkpatch.pl now enforces certain commit citing style, yours 
doesn't quite match it.

> This fixes the done condition that advances the musb schedule. Without this
> patch the the msub_advance_schedule() is called immediately after receiving an
> endpoint rx interrupt without waiting for the dma transfer to complete. As a
> consequence when the dma complete interrupt arrives the in_qh member of hw_ep
> is already null an the musb_host_rx() exits on !urb error case.
>
> Signed-off-by: Cristian Birsan <cristian.birsan@...rochip.com>
> Signed-off-by: Joshua Henderson <joshua.henderson@...rochip.com>
> ---
>   drivers/usb/musb/musb_host.c |    5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
> index 795a45b..3fdc99b 100644
> --- a/drivers/usb/musb/musb_host.c
> +++ b/drivers/usb/musb/musb_host.c
> @@ -1825,6 +1825,7 @@ void musb_host_rx(struct musb *musb, u8 epnum)
>   	u16			rx_csr, val;
>   	bool			iso_err = false;
>   	bool			done = false;
> +	int			ret;
>   	u32			status;
>   	struct dma_channel	*dma;
>   	unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG;
> @@ -2003,10 +2004,10 @@ void musb_host_rx(struct musb *musb, u8 epnum)
>   				qh->offset,
>   				urb->transfer_buffer_length);
>
> -			done = musb_rx_dma_in_inventra_cppi41(c, hw_ep, qh,
> +			ret = musb_rx_dma_in_inventra_cppi41(c, hw_ep, qh,
>   							      urb, xfer_len,
>   							      iso_err);
> -			if (done)
> +			if (ret)

    Hm, does that really fix anything?

>   				goto finish;
>   			else
>   				dev_err(musb->controller, "error: rx_dma failed\n");

MBR, Sergei