Re: [PATCH v2] i2c-omap: Double clear of ARDY status in IRQ handler

[Tony Lindgren <tony@atomide.com>]

* Keerthy <j-keerthy@ti.com> [110215 20:53]:
> From: Richard woodruff <r-woodruff2@ti.com>
> 
> This errata occurs when the ARDY interrupt generation is enabled.
> At the begining of every new transaction the ARDY interrupt is cleared.
> 
> On continuous i2c transactions where after clearing the ARDY bit from
> I2C_STAT register (clearing the interrupt), the IRQ line is reasserted and the
> I2C_STAT[ARDY] bit set again on 1. In fact, the ARDY status bit is not cleared
> at the write access to I2C_STAT[ARDY] and only the IRQ line is deasserted and
> then reasserted. This is not captured in the usual errata documents.
> 
> The workaround is to have a double clear of ARDY status in irq handler.

I'll add this to omap-testing for few days and then if no issue Ben
can merge this.

Regards,

Tony
 
> Signed-off-by: Richard woodruff <r-woodruff2@ti.com>
> Signed-off-by: Keerthy <j-keerthy@ti.com>
> ---
>  drivers/i2c/busses/i2c-omap.c |    6 +++++-
>  1 files changed, 5 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index b605ff3..5b35cf4 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -847,11 +847,15 @@ complete:
>  			dev_err(dev->dev, "Arbitration lost\n");
>  			err |= OMAP_I2C_STAT_AL;
>  		}
> +		/* 
> +		 * ProDB0017052: Clear ARDY bit twice
> +		 */ 
>  		if (stat & (OMAP_I2C_STAT_ARDY | OMAP_I2C_STAT_NACK |
>  					OMAP_I2C_STAT_AL)) {
>  			omap_i2c_ack_stat(dev, stat &
>  				(OMAP_I2C_STAT_RRDY | OMAP_I2C_STAT_RDR |
> -				OMAP_I2C_STAT_XRDY | OMAP_I2C_STAT_XDR));
> +				OMAP_I2C_STAT_XRDY | OMAP_I2C_STAT_XDR |
> +				OMAP_I2C_STAT_ARDY));
>  			omap_i2c_complete_cmd(dev, err);
>  			return IRQ_HANDLED;
>  		}
> -- 
> 1.7.0.4
> 
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