linux-kernel - Re: [PATCH 3/3] usb: musb: musb_cppi41: Handle ISOCH differently and not use the hrtimer.

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Message-ID: <52E2A6F7.7010301@cogentembedded.com>
Date:	Fri, 24 Jan 2014 21:46:31 +0400
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	George Cherian <george.cherian@...com>, linux-usb@...r.kernel.org
CC:	balbi@...com, gregkh@...uxfoundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] usb: musb: musb_cppi41: Handle ISOCH differently
 and not use the hrtimer.

Hello.

On 24-01-2014 18:14, George Cherian wrote:

> In case of ISOCH transfers the hrtimer workaround for the hardware issue
> is not very reliable. Instead of checking musb_is_tx_fifo_empty() in hrtimer
> routine, schedule a completion work and check the same in completion work.

> Signed-off-by: George Cherian <george.cherian@...com>
> ---
>   drivers/usb/musb/musb_cppi41.c | 54 +++++++++++++++++++++++++++++++++++++++++-
>   1 file changed, 53 insertions(+), 1 deletion(-)

> diff --git a/drivers/usb/musb/musb_cppi41.c b/drivers/usb/musb/musb_cppi41.c
> index 39ee516..8075562 100644
> --- a/drivers/usb/musb/musb_cppi41.c
> +++ b/drivers/usb/musb/musb_cppi41.c
[...]
> @@ -165,6 +178,32 @@ static void cppi41_trans_done(struct cppi41_dma_channel *cppi41_channel)
>   	}
>   }
>
> +static void cppi_trans_done_work(struct work_struct *work)
> +{
> +	unsigned long flags;
> +	struct cppi41_dma_channel *cppi41_channel =
> +		container_of(work, struct cppi41_dma_channel, dma_completion);
> +	struct cppi41_dma_controller *controller = cppi41_channel->controller;
> +	struct musb *musb = controller->musb;
> +	struct musb_hw_ep *hw_ep = cppi41_channel->hw_ep;
> +	bool empty;
> +
> +	if (!cppi41_channel->is_tx && is_isoc(hw_ep, 1)) {
> +			spin_lock_irqsave(&musb->lock, flags);
> +			cppi41_trans_done(cppi41_channel);
> +			spin_unlock_irqrestore(&musb->lock, flags);

    This *if* arm is clearly over-indented by one tab. Compare with below 
*else* arm.

> +	} else {
> +		empty = musb_is_tx_fifo_empty(hw_ep);
> +		if (empty) {
> +			spin_lock_irqsave(&musb->lock, flags);
> +			cppi41_trans_done(cppi41_channel);
> +			spin_unlock_irqrestore(&musb->lock, flags);
> +		} else {
> +			schedule_work(&cppi41_channel->dma_completion);
> +		}
> +	}
> +}
> +

WBR, Sergei

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