linux-kernel - Re: [PATCH 2/2] usb: musb: Fix DMA desired mode for Mentor DMA engine

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Date:	Tue, 2 Feb 2016 16:32:52 +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 2/2] usb: musb: Fix DMA desired mode for Mentor DMA engine

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

> From: Cristian Birsan <cristian.birsan@...rochip.com>
>
> Commit 6b6e97107f12f3a9f7 (USB: musb: fix isochronous TXDMA (take 2)) introduces

    Again, wrong commit style. And I really doubt that blaming my commit was 
correct. :-)

> a problem setting the desired channel mode for the Mentor DMA engine.
>
> There is a case where the pointer of the channel DMA mode is incorrectly
> assigned to a pointer value, when it should be assigned the actual mode value.
> This results in the value of channel->desired_mode not being correct.
>
> Signed-off-by: Cristian Birsan <cristian.birsan@...rochip.com>
> Signed-off-by: Joshua Henderson <joshua.henderson@...rochip.com>
> ---
>   drivers/usb/musb/musb_host.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
> index 3fdc99b..748379e 100644
> --- a/drivers/usb/musb/musb_host.c
> +++ b/drivers/usb/musb/musb_host.c
> @@ -662,7 +662,7 @@ static int musb_tx_dma_set_mode_mentor(struct dma_controller *dma,

    Hm, there was no such function at the time of my commit...

>   		csr &= ~(MUSB_TXCSR_AUTOSET | MUSB_TXCSR_DMAMODE);
>   		csr |= MUSB_TXCSR_DMAENAB; /* against programmer's guide */
>   	}
> -	channel->desired_mode = mode;
> +	channel->desired_mode = *mode;

   'mode' was 'u8' at the time of my commit, see:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6b6e97107f12f3a9f7b5b43a6c3b94409240bcff

    I think that the recent commit below should be blamed instead:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=754fe4a92c072a6e36d89fa328ed789c9ebc1af5

[...]

MBR, Sergei