Re: [PATCH 3/5] i2c: omap: handle all irqs befor unblocking omap_i2c_xfer_msg()

From: Grygorii Strashko
Date: Wed Jun 19 2013 - 14:47:39 EST

Hi Felipe,
On 06/07/2013 10:05 PM, Felipe Balbi wrote:

On Fri, Jun 07, 2013 at 09:46:06PM +0300, Grygorii Strashko wrote:
ARDY|NACK and ARDY|AL are set together in OMAP_I2C_STAT_REG, which will be
Have you seen that happen ever ? AL is Arbitration Lost, we never put
OMAP in a multi-master environment before.
This is an example from real life:
[ 0.271942] omap_i2c omap_i2c.1: bus 1 rev2.4.0 at 400 kHz
[ 1.283416] omap_i2c omap_i2c.1: timeout waiting for bus ready
[ 1.300109] OMAP_I2C DEBUG: stat=1001
[ 1.300140] omap_i2c omap_i2c.1: Arbitration lost
[ 1.300140] OMAP_I2C DEBUG: IE=601F
[ 1.300140] OMAP_I2C DEBUG: STAT=1000
[ 1.300170] OMAP_I2C DEBUG: IV=636F
[ 1.300170] OMAP_I2C DEBUG: WE=636F
[ 1.300170] OMAP_I2C DEBUG: SYSS=1
[ 1.300170] OMAP_I2C DEBUG: BUF=707
[ 1.300201] OMAP_I2C DEBUG: CNT=1
[ 1.300201] OMAP_I2C DEBUG: DATA=1
[ 1.300201] OMAP_I2C DEBUG: SYSC=215
[ 1.300201] OMAP_I2C DEBUG: CON=8200
[ 1.300231] OMAP_I2C DEBUG: OA=0
[ 1.300231] OMAP_I2C DEBUG: SA=49
[ 1.300231] OMAP_I2C DEBUG: PSC=9
[ 1.300262] OMAP_I2C DEBUG: SCLL=9
[ 1.300262] OMAP_I2C DEBUG: SCLH=3
[ 1.300262] OMAP_I2C DEBUG: SYSTEST=1E0
[ 1.300262] OMAP_I2C DEBUG: BUFSTAT=4000

and my headache now :..(

ARDY | NACK I also find it a bit hard for those two to happen together
since ARDY will be set when you can change controller's register
*again*, mening that a transfer has completed.
There are examples:
[ 3.544952] omap_i2c 48060000.i2c: IRQ (ISR = 0x0006)

[ 25.574523] omap_i2c 48350000.i2c: IRQ (ISR = 0x0014)
[ 25.579925] omap_i2c 48350000.i2c: IRQ (ISR = 0x0012)

to see it - enable debug output in omap_i2c_isr_thread:
dev_dbg(dev->dev, "IRQ (ISR = 0x%04x)\n", stat);

Also, we need to follow what the programming model says. And, I don't
have docs with me right now, but IIRC it tells us to bail out if any of
the error conditions are met.

yep, but first of all - all IRQs need to be acked before exit.

Sorry, for delayed reply - I've had problems with my e-mail.

- grygorii

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