Re: [PATCH v4] OMAP2/3: I2C: Errata ID i207: Clear wrong RDR interrupt

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Mon, Apr 19, 2010 at 12:44:22PM +0530, Manjunatha GK wrote:
> Under certain rare conditions, I2C_STAT[13].RDR bit may be set
> and the corresponding interrupt fire, even there is no data in
> the receive FIFO, or the I2C data transfer is still ongoing.
> These spurious RDR events must be ignored by the software.
> 
> This patch handles and ignores RDR spurious interrupts.
> 
> The below sequence is required in interrupt handler for
> handling this errata:
> 1. If RDR is set to 1, clear RDR
> 2. Read I2C status register and check for BusBusy bit. If BusBusy
> bit is set, skip remaining steps.
> 3. If BusBusy bit is not set, perform read operation on I2C status
> register.
> 4. If RDR is set, clear the same. Check RDR again and clear if it sets
> RDR bit again.
> 5. Perform I2C Data Read operation N number of times(where N is value
> read from the register BUFSTAT-RXSTAT bit fields).
> 
> Note : This errata is applicable for OMAP2 and OMAP3 platforms only.
> It is not applicable for OMAP4.

If people can give me a yes/no before the end of play tomorrow (ie,
2300GMT) then I will get this applied to for-linus/i2c and send it
for -rc.
 
> Signed-off-by: Manjunatha GK <manjugk@xxxxxx>
> Cc: linux-i2c@xxxxxxxxxxxxxxx
> Cc: ben-linux@xxxxxxxxx
> Cc: Kalliguddi, Hema <hemahk@xxxxxx>
> Cc: Nishanth Menon <nm@xxxxxx>
> Cc: Aaro Koskinen <Aaro.Koskinen@xxxxxxxxx>
> 
> ---
>  drivers/i2c/busses/i2c-omap.c |   28 ++++++++++++++++++++++++++++
>  1 files changed, 28 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index f2019d2..8309eac 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -796,6 +796,34 @@ complete:
>  		}
>  		if (stat & (OMAP_I2C_STAT_RRDY | OMAP_I2C_STAT_RDR)) {
>  			u8 num_bytes = 1;
> +
> +			/*
> +			 * I2C Errata(Errata Nos. OMAP2: 1.67, OMAP3: 1.8)
> +			 * Not applicable for OMAP4.
> +			 * Under certain rare conditions, RDR could be set again
> +			 * when the bus is busy, then ignore the interrupt and
> +			 * clear the interrupt.
> +			 */
> +			if ((stat & OMAP_I2C_STAT_RDR) && !cpu_is_omap44xx()) {
> +				/* Step 1: If RDR is set, clear it */
> +				omap_i2c_ack_stat(dev, OMAP_I2C_STAT_RDR);
> +
> +				/* Step 2: */
> +				if(!(omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG)
> +							& OMAP_I2C_STAT_BB)) {
> +					/* Step 3: */
> +					if(omap_i2c_read_reg(dev,
> +						OMAP_I2C_STAT_REG)
> +							& OMAP_I2C_STAT_RDR) {
> +						omap_i2c_ack_stat(dev,
> +							OMAP_I2C_STAT_RDR);
> +						dev_err(dev->dev,
> +						"RDR when the bus is busy.\n");
> +						continue;
> +					}
> +
> +				}
> +			}
>  			if (dev->fifo_size) {
>  				if (stat & OMAP_I2C_STAT_RRDY)
>  					num_bytes = dev->fifo_size;
> -- 
> 1.6.0.4
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 
Ben (ben@xxxxxxxxx, http://www.fluff.org/)

  'a smiley only costs 4 bytes'
--
To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Index of Archives]     [Linux GPIO]     [Linux SPI]     [Linux Hardward Monitoring]     [LM Sensors]     [Linux USB Devel]     [Linux Media]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux