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i2c: omap: fix i207 errata handling

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commit 6d9939f651 (i2c: omap: split out [XR]DR
and [XR]RDY) changed the way how errata i207 (I2C: RDR Flag May Be Incorrectly
Set) get handled. 6d9939f651 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 6d9939f651 way of handling errata.

Found by code review. Real impact haven't seen.
Tested on Beagleboard XM C.

Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com>
Fixes: 6d9939f651 i2c: omap: split out [XR]DR and [XR]RDY
Tested-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Alexander Kochetkov 2014-11-21 04:16:51 +04:00 committed by Wolfram Sang
parent d39f77b06a
commit ccfc866356
1 changed files with 5 additions and 3 deletions
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8
drivers/i2c/busses/i2c-omap.c
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@ -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;
}