i2c: omap: fix i207 errata handling

commit 6d9939f (i2c: omap: split out [XR]DR and [XR]RDY) changed the way how errata i207 (I2C: RDR Flag May Be Incorrectly Set) get handled. 6d9939f code doesn't correspond to workaround provided by errata. According to errata ISR must filter out spurious RDR before data read not after. ISR must read RXSTAT to get number of bytes available to read. Because RDR could be set while there could no data in the receive FIFO. Restored pre 6d9939f way of handling errata. Found by code review. Real impact haven't seen. Tested on Beagleboard XM C. Signed-off-by: Alexander Kochetkov <[email protected]> Fixes: 6d9939f i2c: omap: split out [XR]DR and [XR]RDY Tested-by: Felipe Balbi <[email protected]> Reviewed-by: Felipe Balbi <[email protected]> Signed-off-by: Wolfram Sang <[email protected]>
Fisiu · Nov 22, 2014 · ccfc866 · ccfc866
1 parent d39f77b
commit ccfc866
Showing 1 changed file with 5 additions and 3 deletions.
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
@@ -952,11 +952,13 @@ omap_i2c_isr_thread(int this_irq, void *dev_id)
 			if (dev->fifo_size)
 				num_bytes = dev->buf_len;
 
-			omap_i2c_receive_data(dev, num_bytes, true);
-
-			if (dev->errata & I2C_OMAP_ERRATA_I207)
+			if (dev->errata & I2C_OMAP_ERRATA_I207) {
 				i2c_omap_errata_i207(dev, stat);
+				num_bytes = (omap_i2c_read_reg(dev,
+					OMAP_I2C_BUFSTAT_REG) >> 8) & 0x3F;
+			}
 
+			omap_i2c_receive_data(dev, num_bytes, true);
 			omap_i2c_ack_stat(dev, OMAP_I2C_STAT_RDR);
 			continue;
 		}