linux-kernel - Re: [PATCH 2/8] i2c: i2c-bfin-twi: Stop receiving operation immediately in last rx interrupt.

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Message-ID: <20120611162807.GC3887@pengutronix.de>
Date:	Mon, 11 Jun 2012 18:28:07 +0200
From:	Wolfram Sang <w.sang@...gutronix.de>
To:	sonic.zhang@...log.com
Cc:	Ben Dooks <ben-linux@...ff.org>, linux-i2c@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>,
	uclinux-dist-devel@...ckfin.uclinux.org
Subject: Re: [PATCH 2/8] i2c: i2c-bfin-twi: Stop receiving operation
 immediately in last rx interrupt.

On Wed, May 16, 2012 at 03:20:20PM +0800, sonic.zhang@...log.com wrote:
> From: Sonic Zhang <sonic.zhang@...log.com>
> 
> Also wake up waiting process when transfer completes.

The description says what you do, but not why it is needed. What bug was
experienced and why is this change proper? Patch 5/8 does that quite
good.

> 
> Signed-off-by: Sonic Zhang <sonic.zhang@...log.com>
> 
> git-svn-id: svn://localhost/svn/linux-kernel/trunk@...5 526b6c2d-f592-4532-a319-5dd88ccb003d

Please remove this line.

> ---
>  drivers/i2c/busses/i2c-bfin-twi.c |   43 ++++++++++++++++++++----------------
>  1 files changed, 24 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-bfin-twi.c b/drivers/i2c/busses/i2c-bfin-twi.c
> index e6dd3c9..376e331 100644
> --- a/drivers/i2c/busses/i2c-bfin-twi.c
> +++ b/drivers/i2c/busses/i2c-bfin-twi.c
> @@ -130,21 +130,25 @@ static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface,
>  			}
>  			iface->transPtr++;
>  			iface->readNum--;
> -		} else if (iface->manual_stop) {
> -			/* Avoid possible bus stall -
> -			 * Flush FIFO before issuing the STOP condition
> -			 */
> -			read_RCV_DATA16(iface);
> -			write_MASTER_CTL(iface,
> -				read_MASTER_CTL(iface) | STOP);
> -		} else if (iface->cur_mode == TWI_I2C_MODE_REPEAT &&
> -		           iface->cur_msg + 1 < iface->msg_num) {
> -			if (iface->pmsg[iface->cur_msg + 1].flags & I2C_M_RD)
> -				write_MASTER_CTL(iface,
> -					read_MASTER_CTL(iface) | RSTART | MDIR);
> -			else
> +		}
> +
> +		if (iface->readNum == 0) {
> +			if (iface->manual_stop) {
> +				/* Avoid possible bus stall -
> +				 * Flush FIFO before issuing the STOP condition
> +				 */
> +				read_RCV_DATA16(iface);
>  				write_MASTER_CTL(iface,
> -					(read_MASTER_CTL(iface) | RSTART) & ~MDIR);
> +					read_MASTER_CTL(iface) | STOP);
> +			} else if (iface->cur_mode == TWI_I2C_MODE_REPEAT &&
> +					iface->cur_msg + 1 < iface->msg_num) {
> +				if (iface->pmsg[iface->cur_msg + 1].flags & I2C_M_RD)
> +					write_MASTER_CTL(iface,
> +						read_MASTER_CTL(iface) | RSTART | MDIR);
> +				else
> +					write_MASTER_CTL(iface,
> +						(read_MASTER_CTL(iface) | RSTART) & ~MDIR);
> +			}
>  		}
>  	}
>  	if (twi_int_status & MERR) {
> @@ -245,12 +249,13 @@ static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface,
>  				}
>  			}
>  
> -			if (iface->pmsg[iface->cur_msg].len <= 255)
> -					write_MASTER_CTL(iface,
> +			if (iface->pmsg[iface->cur_msg].len <= 255) {
> +				write_MASTER_CTL(iface,
>  					(read_MASTER_CTL(iface) &
>  					(~(0xff << 6))) |
> -				(iface->pmsg[iface->cur_msg].len << 6));
> -			else {
> +					(iface->pmsg[iface->cur_msg].len << 6));
> +				iface->manual_stop = 0;
> +			} else {
>  				write_MASTER_CTL(iface,
>  					(read_MASTER_CTL(iface) |
>  					(0xff << 6)));
> @@ -264,8 +269,8 @@ static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface,
>  			write_INT_MASK(iface, 0);
>  			write_MASTER_CTL(iface, 0);
>  		}
> +		complete(&iface->complete);
>  	}
> -	complete(&iface->complete);
>  }
>  
>  /* Interrupt handler */
> -- 
> 1.7.0.4
> 
> 
> --
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Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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