Re: [PATCH 1/2] i2c: omap: fix NACK and Arbitration Lost irq handling

[Felipe Balbi <balbi-l0cyMroinI0@public.gmane.org>]

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On Sat, Nov 15, 2014 at 05:20:51AM +0400, Alexander Kochetkov wrote:
> commit 1d7afc95946487945cc7f5019b41255b72224b70 (i2c: omap: ack IRQ in parts)
> changed the interrupt handler to complete transfers without clearing
> XRDY (AL case) and ARDY (NACK case) flags. XRDY or ARDY interrupt will be
> fired again (in parallel with omap_i2c_xfer_msg). Interrupt handler will
> complete transfers second time. As a result, NACK and AL transfers
> terminates with "transfer timeout" and sometimes client code segfault.
> 
> The patch restore original logic of handling NACK and AL interrupts and
> fix race between interrupt handler and omap_i2c_xfer_msg (for AL and
> NACK case only).
> 
> Tested on Beagleboard XM C.
> 

Assuming this is really correct (I haven't tested), you need to add:

Fixes: 1d7afc9 i2c: omap: ack IRQ in parts
Cc: <stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org> # v3.7+

here and resend, so it gets backported to older kernels.

> Signed-off-by: Alexander Kochetkov <al.kochet-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  drivers/i2c/busses/i2c-omap.c |    2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index 90dcc2e..9af7095 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -926,14 +926,12 @@ omap_i2c_isr_thread(int this_irq, void *dev_id)
>  		if (stat & OMAP_I2C_STAT_NACK) {
>  			err |= OMAP_I2C_STAT_NACK;
>  			omap_i2c_ack_stat(dev, OMAP_I2C_STAT_NACK);
> -			break;
>  		}
>  
>  		if (stat & OMAP_I2C_STAT_AL) {
>  			dev_err(dev->dev, "Arbitration lost\n");
>  			err |= OMAP_I2C_STAT_AL;
>  			omap_i2c_ack_stat(dev, OMAP_I2C_STAT_AL);
> -			break;
>  		}
>  
>  		/*
> -- 
> 1.7.9.5
> 

-- 
balbi

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