linux-kernel - Re: [PATCH v3 1/2] usb: musb: Fix DMA for host mode

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Message-ID: <56BCC7F5.3030500@cogentembedded.com>
Date:	Thu, 11 Feb 2016 20:42:13 +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@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org
Subject: Re: [PATCH v3 1/2] usb: musb: Fix DMA for host mode

On 02/11/2016 06:58 PM, Joshua Henderson wrote:

> From: Cristian Birsan <cristian.birsan@...rochip.com>
>
> Commit ac33cdb16681 ("usb: musb: Remove ifdefs for musb_host_rx in
> musb_host.c part5") introduces a problem setting DMA host mode.
>
> This commit 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.

    You're supposed to document your own changes above --- when you're pushing 
someone other's patch... in this minimalistic patch, the changes were so 
dramatic that you could have changed the authorship instead...

> Signed-off-by: Cristian Birsan <cristian.birsan@...rochip.com>
> Signed-off-by: Joshua Henderson <joshua.henderson@...rochip.com>

> ---
> Changes since v2:
> 	- Put function call in if condition.
> Changes since v1:
> 	- Don't add unecessary new variable. Just correct done.
> ---
>   drivers/usb/musb/musb_host.c |    7 +++----
>   1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
> index 795a45b..6a81066 100644
> --- a/drivers/usb/musb/musb_host.c
> +++ b/drivers/usb/musb/musb_host.c
> @@ -2003,10 +2003,9 @@ 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,
> -							      urb, xfer_len,
> -							      iso_err);
> -			if (done)
> +			if (musb_rx_dma_in_inventra_cppi41(c, hw_ep, qh,
> +							   urb, xfer_len,
> +							   iso_err))

    Can be compressed to 2 lines.

[...]

    Other than that, I'm content now. :-)

MBR, Sergei