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. Patch tested on OMAP zoom3 board. Signed-off-by: Manjunatha GK <manjugk@xxxxxx> Cc: linux-omap@xxxxxxxxxxxxxxx Cc: linux-i2c@xxxxxxxxxxxxxxx Cc: ben-linux@xxxxxxxxx Cc: Kalliguddi, Hema <hemahk@xxxxxx> Cc: Nishanth Menon <nm@xxxxxx> --- Review comments for earlier post can be found at: https://patchwork.kernel.org/patch/90122/ drivers/i2c/busses/i2c-omap.c | 32 +++++++++++++++++++++++++++++++- 1 files changed, 31 insertions(+), 1 deletions(-) diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index ae6f5c1..d4ec886 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -733,10 +733,40 @@ 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, stat & OMAP_I2C_STAT_RDR); + + /* Step 2: */ + if(!(omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG) + & OMAP_I2C_STAT_BB)) { + /* Step 3: */ + while(omap_i2c_read_reg(dev, + OMAP_I2C_STAT_REG) + & OMAP_I2C_STAT_RDR) { + omap_i2c_ack_stat(dev, stat + & OMAP_I2C_STAT_RDR); + dev_err(dev->dev, + "I2C : RDR when the bus is busy.\n"); + continue; + } + + } + else + return IRQ_HANDLED; + } if (dev->fifo_size) { if (stat & OMAP_I2C_STAT_RRDY) num_bytes = dev->fifo_size; - else /* read RXSTAT on RDR interrupt */ + else /* Step4: read RXSTAT on RDR interrupt */ num_bytes = (omap_i2c_read_reg(dev, OMAP_I2C_BUFSTAT_REG) >> 8) & 0x3F; -- 1.6.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
