On 04/13/2010 07:01 AM, G, Manjunath Kondaiah 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.
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/
Overall, the comments have not been implemented, so my NAK continues
unfortunately. please review the comments again.
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;
continue in the inner while loop? NAK. should have been an if condition
here.
+ }
+
+ }
+ else
+ return IRQ_HANDLED;
using a continue is better as commented for patch v1.
+ }
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 */
dont really need this..
num_bytes = (omap_i2c_read_reg(dev,
OMAP_I2C_BUFSTAT_REG)
>> 8)& 0x3F;
Regards,
Nishanth Menon
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