-----Original Message-----
From: Tao Ren [mailto:rentao.bupt@gmail.com]
Sent: Wednesday, August 26, 2020 4:05 AM
To: Eddie James <eajames@linux.ibm.com>
Cc: Joel Stanley <joel@jms.id.au>; devicetree <redacted>;
linux-aspeed [off-list ref]; dmitry.torokhov@gmail.com;
Brendan Higgins [off-list ref]; Linux Kernel Mailing List
[off-list ref]; Rob Herring [off-list ref];
linux-i2c@vger.kernel.org; linux-input@vger.kernel.org; Ryan Chen
[off-list ref]
Subject: Re: [PATCH 3/5] i2c: aspeed: Mask IRQ status to relevant bits

On Tue, Aug 25, 2020 at 02:47:51PM -0500, Eddie James wrote:

quoted

On 8/25/20 1:38 AM, Joel Stanley wrote:

quoted

On Thu, 20 Aug 2020 at 16:12, Eddie James [off-list ref]

wrote:

quoted

quoted

quoted

Mask the IRQ status to only the bits that the driver checks. This
prevents excessive driver warnings when operating in slave mode
when additional bits are set that the driver doesn't handle.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
  drivers/i2c/busses/i2c-aspeed.c | 1 +
  1 file changed, 1 insertion(+)

diff --git a/drivers/i2c/busses/i2c-aspeed.c

b/drivers/i2c/busses/i2c-aspeed.c index 31268074c422..abf40f2af8b4
100644

--- a/drivers/i2c/busses/i2c-aspeed.c
+++ b/drivers/i2c/busses/i2c-aspeed.c

@@ -604,6 +604,7 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq,

void *dev_id)

quoted

quoted

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         writel(irq_received & ~ASPEED_I2CD_INTR_RX_DONE,
                bus->base + ASPEED_I2C_INTR_STS_REG);
         readl(bus->base + ASPEED_I2C_INTR_STS_REG);
+       irq_received &= 0xf000ffff;
         irq_remaining = irq_received;

This would defeat the check for irq_remaining. I don't think we want to do

this.

quoted

quoted

Can you explain why these bits are being set in slave mode?

No, I don't have any documentation for the bits that are masked off
here, so I don't know why they would get set.

The check for irq_remaining is still useful for detecting that the
driver state machine might be out of sync with what the master is doing.

I have a similar patch in my local tree, and the reason being: AST2600 I2C
Controller may set I2CD10[25:24] to report Current Slave Parking Status
(defined in new register I2CS24) even though the new register mode is off. The
2 bits can be ignored in legacy mode, and Ryan from ASPEED could confirm it.

Yes, in AST2600 i2cd10[25:24] will be the same with new mode register i2cs24[25:24]
Thanks Tao.

Cheers,

Tao