[PATCH 1/1] I2C: designware: fix IO timeout issue for AMD controller

[PATCH 1/1] I2C: designware: fix IO timeout issue for AMD controller

[Xiangliang Yu]

Because of some hardware limitation, AMD I2C controller can't
trigger next interrupt if interrupt status has been changed
after clearing interrupt status bits. Then, I2C will lost
interrupt and IO timeout.

According to hardware design, this patch implements a workaround
to disable i2c controller interrupt after clearing interrupt bits
when entering ISR and to enable i2c interrupt before exiting ISR.

To reduce the performance impacts on other vendors, use unlikely
function to check flag in ISR.

Signed-off-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
---
 drivers/i2c/busses/i2c-designware-core.c    | 6 ++++++
 drivers/i2c/busses/i2c-designware-core.h    | 1 +
 drivers/i2c/busses/i2c-designware-platdrv.c | 4 ++++
 3 files changed, 11 insertions(+)

diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 7441cdc..04e7b65 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -783,6 +783,9 @@ irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
 
 	stat = i2c_dw_read_clear_intrbits(dev);
 
+	if (unlikely(dev->accessor_flags & ACCESS_INTR_MASK))
+		i2c_dw_disable_int(dev);
+
 	if (stat & DW_IC_INTR_TX_ABRT) {
 		dev->cmd_err |= DW_IC_ERR_TX_ABRT;
 		dev->status = STATUS_IDLE;
@@ -811,6 +814,9 @@ tx_aborted:
 	if ((stat & (DW_IC_INTR_TX_ABRT | DW_IC_INTR_STOP_DET)) || dev->msg_err)
 		complete(&dev->cmd_complete);
 
+	if (unlikely(dev->accessor_flags & ACCESS_INTR_MASK))
+		dw_writel(dev, DW_IC_INTR_DEFAULT_MASK, DW_IC_INTR_MASK);
+
 	return IRQ_HANDLED;
 }
 EXPORT_SYMBOL_GPL(i2c_dw_isr);
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 9630222..808ef6a 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -111,6 +111,7 @@ struct dw_i2c_dev {
 
 #define ACCESS_SWAP		0x00000001
 #define ACCESS_16BIT		0x00000002
+#define ACCESS_INTR_MASK	0x00000004
 
 extern u32 dw_readl(struct dw_i2c_dev *dev, int offset);
 extern void dw_writel(struct dw_i2c_dev *dev, u32 b, int offset);
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 472b882..0c59357 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -251,6 +251,10 @@ static int dw_i2c_probe(struct platform_device *pdev)
 		dev->rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
 		dev->adapter.nr = pdev->id;
 	}
+
+	if (!strncmp(pdev->name, "AMD0010", 7))
+		dev->accessor_flags |= ACCESS_INTR_MASK;
+
 	r = i2c_dw_init(dev);
 	if (r)
 		return r;
-- 
1.9.1

Re: [PATCH 1/1] I2C: designware: fix IO timeout issue for AMD controller

[Mika Westerberg]

On Thu, Nov 05, 2015 at 08:34:44PM +0800, Xiangliang Yu wrote:
> Because of some hardware limitation, AMD I2C controller can't
> trigger next interrupt if interrupt status has been changed
> after clearing interrupt status bits. Then, I2C will lost
> interrupt and IO timeout.
> 
> According to hardware design, this patch implements a workaround
> to disable i2c controller interrupt after clearing interrupt bits
> when entering ISR and to enable i2c interrupt before exiting ISR.
> 
> To reduce the performance impacts on other vendors, use unlikely
> function to check flag in ISR.
> 
> Signed-off-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
> ---
>  drivers/i2c/busses/i2c-designware-core.c    | 6 ++++++
>  drivers/i2c/busses/i2c-designware-core.h    | 1 +
>  drivers/i2c/busses/i2c-designware-platdrv.c | 4 ++++
>  3 files changed, 11 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
> index 7441cdc..04e7b65 100644
> --- a/drivers/i2c/busses/i2c-designware-core.c
> +++ b/drivers/i2c/busses/i2c-designware-core.c
> @@ -783,6 +783,9 @@ irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
>  
>  	stat = i2c_dw_read_clear_intrbits(dev);

What if the status changes right here, before you go and mask the
interrupt?

>  
> +	if (unlikely(dev->accessor_flags & ACCESS_INTR_MASK))
> +		i2c_dw_disable_int(dev);
> +
>  	if (stat & DW_IC_INTR_TX_ABRT) {
>  		dev->cmd_err |= DW_IC_ERR_TX_ABRT;
>  		dev->status = STATUS_IDLE;
> @@ -811,6 +814,9 @@ tx_aborted:
>  	if ((stat & (DW_IC_INTR_TX_ABRT | DW_IC_INTR_STOP_DET)) || dev->msg_err)
>  		complete(&dev->cmd_complete);
>  
> +	if (unlikely(dev->accessor_flags & ACCESS_INTR_MASK))
> +		dw_writel(dev, DW_IC_INTR_DEFAULT_MASK, DW_IC_INTR_MASK);

The driver disables TX interrupt when it is not needed anymore or when
TX gets aborted but the above will re-enable all interrupts regardless.
Is that the intention?

> +
>  	return IRQ_HANDLED;
>  }
>  EXPORT_SYMBOL_GPL(i2c_dw_isr);
> diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
> index 9630222..808ef6a 100644
> --- a/drivers/i2c/busses/i2c-designware-core.h
> +++ b/drivers/i2c/busses/i2c-designware-core.h
> @@ -111,6 +111,7 @@ struct dw_i2c_dev {
>  
>  #define ACCESS_SWAP		0x00000001
>  #define ACCESS_16BIT		0x00000002
> +#define ACCESS_INTR_MASK	0x00000004
>  
>  extern u32 dw_readl(struct dw_i2c_dev *dev, int offset);
>  extern void dw_writel(struct dw_i2c_dev *dev, u32 b, int offset);
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index 472b882..0c59357 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -251,6 +251,10 @@ static int dw_i2c_probe(struct platform_device *pdev)
>  		dev->rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
>  		dev->adapter.nr = pdev->id;
>  	}
> +
> +	if (!strncmp(pdev->name, "AMD0010", 7))
> +		dev->accessor_flags |= ACCESS_INTR_MASK;
> +

Can't you put this to ->driver_data? For example it could refer to a
configuration structure that then contains quirk flags.

>  	r = i2c_dw_init(dev);
>  	if (r)
>  		return r;
> -- 
> 1.9.1

RE: [PATCH 1/1] I2C: designware: fix IO timeout issue for AMD controller

[Yu, Xiangliang]

> -----Original Message-----
> From: Mika Westerberg [mailto:mika.westerberg@linux.intel.com]
> Sent: Thursday, November 05, 2015 9:52 PM
> To: Yu, Xiangliang
> Cc: andriy.shevchenko@linux.intel.com; jarkko.nikula@linux.intel.com;
> wsa@the-dreams.de; linux-i2c@vger.kernel.org; linux-
> kernel@vger.kernel.org; Xue, Ken; Wan, Vincent; Huang, Ray; Wang, Annie;
> Li, Tony
> Subject: Re: [PATCH 1/1] I2C: designware: fix IO timeout issue for AMD
> controller
> 
> On Thu, Nov 05, 2015 at 08:34:44PM +0800, Xiangliang Yu wrote:
> > Because of some hardware limitation, AMD I2C controller can't trigger
> > next interrupt if interrupt status has been changed after clearing
> > interrupt status bits. Then, I2C will lost interrupt and IO timeout.
> >
> > According to hardware design, this patch implements a workaround to
> > disable i2c controller interrupt after clearing interrupt bits when
> > entering ISR and to enable i2c interrupt before exiting ISR.
> >
> > To reduce the performance impacts on other vendors, use unlikely
> > function to check flag in ISR.
> >
> > Signed-off-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
> > ---
> >  drivers/i2c/busses/i2c-designware-core.c    | 6 ++++++
> >  drivers/i2c/busses/i2c-designware-core.h    | 1 +
> >  drivers/i2c/busses/i2c-designware-platdrv.c | 4 ++++
> >  3 files changed, 11 insertions(+)
> >
> > diff --git a/drivers/i2c/busses/i2c-designware-core.c
> > b/drivers/i2c/busses/i2c-designware-core.c
> > index 7441cdc..04e7b65 100644
> > --- a/drivers/i2c/busses/i2c-designware-core.c
> > +++ b/drivers/i2c/busses/i2c-designware-core.c
> > @@ -783,6 +783,9 @@ irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
> >
> >  	stat = i2c_dw_read_clear_intrbits(dev);
> 
> What if the status changes right here, before you go and mask the interrupt?
Have no effect, because i2c controller can't trigger next interrupt.

> 
> >
> > +	if (unlikely(dev->accessor_flags & ACCESS_INTR_MASK))
> > +		i2c_dw_disable_int(dev);
> > +
> >  	if (stat & DW_IC_INTR_TX_ABRT) {
> >  		dev->cmd_err |= DW_IC_ERR_TX_ABRT;
> >  		dev->status = STATUS_IDLE;
> > @@ -811,6 +814,9 @@ tx_aborted:
> >  	if ((stat & (DW_IC_INTR_TX_ABRT | DW_IC_INTR_STOP_DET)) ||
> dev->msg_err)
> >  		complete(&dev->cmd_complete);
> >
> > +	if (unlikely(dev->accessor_flags & ACCESS_INTR_MASK))
> > +		dw_writel(dev, DW_IC_INTR_DEFAULT_MASK,
> DW_IC_INTR_MASK);
> 
> The driver disables TX interrupt when it is not needed anymore or when TX
> gets aborted but the above will re-enable all interrupts regardless.
> Is that the intention?
No, i2c controller can trigger next interrupt only after re-enable all interrupt.

> 
> > +
> >  	return IRQ_HANDLED;
> >  }
> >  EXPORT_SYMBOL_GPL(i2c_dw_isr);
> > diff --git a/drivers/i2c/busses/i2c-designware-core.h
> > b/drivers/i2c/busses/i2c-designware-core.h
> > index 9630222..808ef6a 100644
> > --- a/drivers/i2c/busses/i2c-designware-core.h
> > +++ b/drivers/i2c/busses/i2c-designware-core.h
> > @@ -111,6 +111,7 @@ struct dw_i2c_dev {
> >
> >  #define ACCESS_SWAP		0x00000001
> >  #define ACCESS_16BIT		0x00000002
> > +#define ACCESS_INTR_MASK	0x00000004
> >
> >  extern u32 dw_readl(struct dw_i2c_dev *dev, int offset);  extern void
> > dw_writel(struct dw_i2c_dev *dev, u32 b, int offset); diff --git
> > a/drivers/i2c/busses/i2c-designware-platdrv.c
> > b/drivers/i2c/busses/i2c-designware-platdrv.c
> > index 472b882..0c59357 100644
> > --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> > @@ -251,6 +251,10 @@ static int dw_i2c_probe(struct platform_device
> *pdev)
> >  		dev->rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
> >  		dev->adapter.nr = pdev->id;
> >  	}
> > +
> > +	if (!strncmp(pdev->name, "AMD0010", 7))
> > +		dev->accessor_flags |= ACCESS_INTR_MASK;
> > +
> 
> Can't you put this to ->driver_data? For example it could refer to a
> configuration structure that then contains quirk flags.
I think it will need to add a function to support it, but the function
Is  rarely used. It will easy to add if i2c driver has quirk mechanisms.
Added code is very simple and have no influence on others.

> 
> >  	r = i2c_dw_init(dev);
> >  	if (r)
> >  		return r;
> > --
> > 1.9.1

Re: [PATCH 1/1] I2C: designware: fix IO timeout issue for AMD controller

[Mika Westerberg]

On Fri, Nov 06, 2015 at 04:34:19AM +0000, Yu, Xiangliang wrote:
> > -----Original Message-----
> > From: Mika Westerberg [mailto:mika.westerberg@linux.intel.com]
> > Sent: Thursday, November 05, 2015 9:52 PM
> > To: Yu, Xiangliang
> > Cc: andriy.shevchenko@linux.intel.com; jarkko.nikula@linux.intel.com;
> > wsa@the-dreams.de; linux-i2c@vger.kernel.org; linux-
> > kernel@vger.kernel.org; Xue, Ken; Wan, Vincent; Huang, Ray; Wang, Annie;
> > Li, Tony
> > Subject: Re: [PATCH 1/1] I2C: designware: fix IO timeout issue for AMD
> > controller
> > 
> > On Thu, Nov 05, 2015 at 08:34:44PM +0800, Xiangliang Yu wrote:
> > > Because of some hardware limitation, AMD I2C controller can't trigger
> > > next interrupt if interrupt status has been changed after clearing
> > > interrupt status bits. Then, I2C will lost interrupt and IO timeout.
> > >
> > > According to hardware design, this patch implements a workaround to
> > > disable i2c controller interrupt after clearing interrupt bits when
> > > entering ISR and to enable i2c interrupt before exiting ISR.
> > >
> > > To reduce the performance impacts on other vendors, use unlikely
> > > function to check flag in ISR.
> > >
> > > Signed-off-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
> > > ---
> > >  drivers/i2c/busses/i2c-designware-core.c    | 6 ++++++
> > >  drivers/i2c/busses/i2c-designware-core.h    | 1 +
> > >  drivers/i2c/busses/i2c-designware-platdrv.c | 4 ++++
> > >  3 files changed, 11 insertions(+)
> > >
> > > diff --git a/drivers/i2c/busses/i2c-designware-core.c
> > > b/drivers/i2c/busses/i2c-designware-core.c
> > > index 7441cdc..04e7b65 100644
> > > --- a/drivers/i2c/busses/i2c-designware-core.c
> > > +++ b/drivers/i2c/busses/i2c-designware-core.c
> > > @@ -783,6 +783,9 @@ irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
> > >
> > >  	stat = i2c_dw_read_clear_intrbits(dev);
> > 
> > What if the status changes right here, before you go and mask the interrupt?
> Have no effect, because i2c controller can't trigger next interrupt.
> 
> > 
> > >
> > > +	if (unlikely(dev->accessor_flags & ACCESS_INTR_MASK))
> > > +		i2c_dw_disable_int(dev);
> > > +
> > >  	if (stat & DW_IC_INTR_TX_ABRT) {
> > >  		dev->cmd_err |= DW_IC_ERR_TX_ABRT;
> > >  		dev->status = STATUS_IDLE;
> > > @@ -811,6 +814,9 @@ tx_aborted:
> > >  	if ((stat & (DW_IC_INTR_TX_ABRT | DW_IC_INTR_STOP_DET)) ||
> > dev->msg_err)
> > >  		complete(&dev->cmd_complete);
> > >
> > > +	if (unlikely(dev->accessor_flags & ACCESS_INTR_MASK))
> > > +		dw_writel(dev, DW_IC_INTR_DEFAULT_MASK,
> > DW_IC_INTR_MASK);
> > 
> > The driver disables TX interrupt when it is not needed anymore or when TX
> > gets aborted but the above will re-enable all interrupts regardless.
> > Is that the intention?
> No, i2c controller can trigger next interrupt only after re-enable all interrupt.

If you get an error the function masks all interrupts and jumps to
tx_aborted label. With this patch you unmask all interrupts again before
exiting the function.

> > 
> > > +
> > >  	return IRQ_HANDLED;
> > >  }
> > >  EXPORT_SYMBOL_GPL(i2c_dw_isr);
> > > diff --git a/drivers/i2c/busses/i2c-designware-core.h
> > > b/drivers/i2c/busses/i2c-designware-core.h
> > > index 9630222..808ef6a 100644
> > > --- a/drivers/i2c/busses/i2c-designware-core.h
> > > +++ b/drivers/i2c/busses/i2c-designware-core.h
> > > @@ -111,6 +111,7 @@ struct dw_i2c_dev {
> > >
> > >  #define ACCESS_SWAP		0x00000001
> > >  #define ACCESS_16BIT		0x00000002
> > > +#define ACCESS_INTR_MASK	0x00000004
> > >
> > >  extern u32 dw_readl(struct dw_i2c_dev *dev, int offset);  extern void
> > > dw_writel(struct dw_i2c_dev *dev, u32 b, int offset); diff --git
> > > a/drivers/i2c/busses/i2c-designware-platdrv.c
> > > b/drivers/i2c/busses/i2c-designware-platdrv.c
> > > index 472b882..0c59357 100644
> > > --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> > > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> > > @@ -251,6 +251,10 @@ static int dw_i2c_probe(struct platform_device
> > *pdev)
> > >  		dev->rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
> > >  		dev->adapter.nr = pdev->id;
> > >  	}
> > > +
> > > +	if (!strncmp(pdev->name, "AMD0010", 7))
> > > +		dev->accessor_flags |= ACCESS_INTR_MASK;
> > > +
> > 
> > Can't you put this to ->driver_data? For example it could refer to a
> > configuration structure that then contains quirk flags.
> I think it will need to add a function to support it, but the function
> Is  rarely used. It will easy to add if i2c driver has quirk mechanisms.
> Added code is very simple and have no influence on others.

What if the next AMD I2C controller needs another quirk, and then
another?

I would rather pass flags or similar (reference to config structure
including flags) with ->driver_data.

> 
> > 
> > >  	r = i2c_dw_init(dev);
> > >  	if (r)
> > >  		return r;
> > > --
> > > 1.9.1

RE: [PATCH 1/1] I2C: designware: fix IO timeout issue for AMD controller

[Yu, Xiangliang]

> -----Original Message-----
> From: Mika Westerberg [mailto:mika.westerberg@linux.intel.com]
> Sent: Friday, November 06, 2015 3:46 PM
> To: Yu, Xiangliang
> Cc: andriy.shevchenko@linux.intel.com; jarkko.nikula@linux.intel.com;
> wsa@the-dreams.de; linux-i2c@vger.kernel.org; linux-
> kernel@vger.kernel.org; Xue, Ken; Wan, Vincent; Huang, Ray; Wang, Annie;
> Li, Tony
> Subject: Re: [PATCH 1/1] I2C: designware: fix IO timeout issue for AMD
> controller
> 
> On Fri, Nov 06, 2015 at 04:34:19AM +0000, Yu, Xiangliang wrote:
> > > -----Original Message-----
> > > From: Mika Westerberg [mailto:mika.westerberg@linux.intel.com]
> > > Sent: Thursday, November 05, 2015 9:52 PM
> > > To: Yu, Xiangliang
> > > Cc: andriy.shevchenko@linux.intel.com;
> > > jarkko.nikula@linux.intel.com; wsa@the-dreams.de;
> > > linux-i2c@vger.kernel.org; linux- kernel@vger.kernel.org; Xue, Ken;
> > > Wan, Vincent; Huang, Ray; Wang, Annie; Li, Tony
> > > Subject: Re: [PATCH 1/1] I2C: designware: fix IO timeout issue for
> > > AMD controller
> > >
> > > On Thu, Nov 05, 2015 at 08:34:44PM +0800, Xiangliang Yu wrote:
> > > > Because of some hardware limitation, AMD I2C controller can't
> > > > trigger next interrupt if interrupt status has been changed after
> > > > clearing interrupt status bits. Then, I2C will lost interrupt and IO timeout.
> > > >
> > > > According to hardware design, this patch implements a workaround
> > > > to disable i2c controller interrupt after clearing interrupt bits
> > > > when entering ISR and to enable i2c interrupt before exiting ISR.
> > > >
> > > > To reduce the performance impacts on other vendors, use unlikely
> > > > function to check flag in ISR.
> > > >
> > > > Signed-off-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
> > > > ---
> > > >  drivers/i2c/busses/i2c-designware-core.c    | 6 ++++++
> > > >  drivers/i2c/busses/i2c-designware-core.h    | 1 +
> > > >  drivers/i2c/busses/i2c-designware-platdrv.c | 4 ++++
> > > >  3 files changed, 11 insertions(+)
> > > >
> > > > diff --git a/drivers/i2c/busses/i2c-designware-core.c
> > > > b/drivers/i2c/busses/i2c-designware-core.c
> > > > index 7441cdc..04e7b65 100644
> > > > --- a/drivers/i2c/busses/i2c-designware-core.c
> > > > +++ b/drivers/i2c/busses/i2c-designware-core.c
> > > > @@ -783,6 +783,9 @@ irqreturn_t i2c_dw_isr(int this_irq, void
> > > > *dev_id)
> > > >
> > > >  	stat = i2c_dw_read_clear_intrbits(dev);
> > >
> > > What if the status changes right here, before you go and mask the
> interrupt?
> > Have no effect, because i2c controller can't trigger next interrupt.
> >
> > >
> > > >
> > > > +	if (unlikely(dev->accessor_flags & ACCESS_INTR_MASK))
> > > > +		i2c_dw_disable_int(dev);
> > > > +
> > > >  	if (stat & DW_IC_INTR_TX_ABRT) {
> > > >  		dev->cmd_err |= DW_IC_ERR_TX_ABRT;
> > > >  		dev->status = STATUS_IDLE;
> > > > @@ -811,6 +814,9 @@ tx_aborted:
> > > >  	if ((stat & (DW_IC_INTR_TX_ABRT | DW_IC_INTR_STOP_DET)) ||
> > > dev->msg_err)
> > > >  		complete(&dev->cmd_complete);
> > > >
> > > > +	if (unlikely(dev->accessor_flags & ACCESS_INTR_MASK))
> > > > +		dw_writel(dev, DW_IC_INTR_DEFAULT_MASK,
> > > DW_IC_INTR_MASK);
> > >
> > > The driver disables TX interrupt when it is not needed anymore or
> > > when TX gets aborted but the above will re-enable all interrupts
> regardless.
> > > Is that the intention?
> > No, i2c controller can trigger next interrupt only after re-enable all interrupt.
> 
> If you get an error the function masks all interrupts and jumps to tx_aborted
> label. With this patch you unmask all interrupts again before exiting the
> function.
> 

I see, how about change if statement to else if?

> > >
> > > > +
> > > >  	return IRQ_HANDLED;
> > > >  }
> > > >  EXPORT_SYMBOL_GPL(i2c_dw_isr);
> > > > diff --git a/drivers/i2c/busses/i2c-designware-core.h
> > > > b/drivers/i2c/busses/i2c-designware-core.h
> > > > index 9630222..808ef6a 100644
> > > > --- a/drivers/i2c/busses/i2c-designware-core.h
> > > > +++ b/drivers/i2c/busses/i2c-designware-core.h
> > > > @@ -111,6 +111,7 @@ struct dw_i2c_dev {
> > > >
> > > >  #define ACCESS_SWAP		0x00000001
> > > >  #define ACCESS_16BIT		0x00000002
> > > > +#define ACCESS_INTR_MASK	0x00000004
> > > >
> > > >  extern u32 dw_readl(struct dw_i2c_dev *dev, int offset);  extern
> > > > void dw_writel(struct dw_i2c_dev *dev, u32 b, int offset); diff
> > > > --git a/drivers/i2c/busses/i2c-designware-platdrv.c
> > > > b/drivers/i2c/busses/i2c-designware-platdrv.c
> > > > index 472b882..0c59357 100644
> > > > --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> > > > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> > > > @@ -251,6 +251,10 @@ static int dw_i2c_probe(struct
> > > > platform_device
> > > *pdev)
> > > >  		dev->rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
> > > >  		dev->adapter.nr = pdev->id;
> > > >  	}
> > > > +
> > > > +	if (!strncmp(pdev->name, "AMD0010", 7))
> > > > +		dev->accessor_flags |= ACCESS_INTR_MASK;
> > > > +
> > >
> > > Can't you put this to ->driver_data? For example it could refer to a
> > > configuration structure that then contains quirk flags.
> > I think it will need to add a function to support it, but the function
> > Is  rarely used. It will easy to add if i2c driver has quirk mechanisms.
> > Added code is very simple and have no influence on others.
> 
> What if the next AMD I2C controller needs another quirk, and then another?
> 
> I would rather pass flags or similar (reference to config structure including
> flags) with ->driver_data.
> 

I don't think there is another quirk.

> >
> > >
> > > >  	r = i2c_dw_init(dev);
> > > >  	if (r)
> > > >  		return r;
> > > > --
> > > > 1.9.1

Re: [PATCH 1/1] I2C: designware: fix IO timeout issue for AMD controller

[Jarkko Nikula]

On 06.11.2015 06:34, Yu, Xiangliang wrote:
>> -----Original Message-----
>> From: Mika Westerberg [mailto:mika.westerberg@linux.intel.com]
>>> --- a/drivers/i2c/busses/i2c-designware-core.c
>>> +++ b/drivers/i2c/busses/i2c-designware-core.c
>>> @@ -783,6 +783,9 @@ irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
>>>
>>>   	stat = i2c_dw_read_clear_intrbits(dev);
>>
>> What if the status changes right here, before you go and mask the interrupt?
> Have no effect, because i2c controller can't trigger next interrupt.
>
Does it mean possible lost interrupt too? I guess it can be debugged by 
placing a few ms long mdelay() between clearing and masking.

How frequent is this timeout? I guess lost interrupt is somehow nearly 
related to clearing, masking and unmasking if that cycle helps. One 
thing that comes to my mind is masking needed and could plain unmasking 
be also a working workaround?

Have you tried to print DW_IC_INTR_STAT, DW_IC_INTR_MASK and 
DW_IC_RAW_INTR_STAT when timeout occurs? E.g. just after printing the 
timeout out error in i2c_dw_xfer(). Probably good in i2c_dw_isr() too if 
if doesn't produce too much data and make debugging impossible.

-- 
Jarkko

RE: [PATCH 1/1] I2C: designware: fix IO timeout issue for AMD controller

[Yu, Xiangliang]

> -----Original Message-----
> From: Jarkko Nikula [mailto:jarkko.nikula@linux.intel.com]
> Sent: Friday, November 06, 2015 5:00 PM
> To: Yu, Xiangliang; Mika Westerberg
> Cc: andriy.shevchenko@linux.intel.com; wsa@the-dreams.de; linux-
> i2c@vger.kernel.org; linux-kernel@vger.kernel.org; Xue, Ken; Wan, Vincent;
> Huang, Ray; Wang, Annie; Li, Tony
> Subject: Re: [PATCH 1/1] I2C: designware: fix IO timeout issue for AMD
> controller
> 
> On 06.11.2015 06:34, Yu, Xiangliang wrote:
> >> -----Original Message-----
> >> From: Mika Westerberg [mailto:mika.westerberg@linux.intel.com]
> >>> --- a/drivers/i2c/busses/i2c-designware-core.c
> >>> +++ b/drivers/i2c/busses/i2c-designware-core.c
> >>> @@ -783,6 +783,9 @@ irqreturn_t i2c_dw_isr(int this_irq, void
> >>> *dev_id)
> >>>
> >>>   	stat = i2c_dw_read_clear_intrbits(dev);
> >>
> >> What if the status changes right here, before you go and mask the
> interrupt?
> > Have no effect, because i2c controller can't trigger next interrupt.
> >
> Does it mean possible lost interrupt too? I guess it can be debugged by
> placing a few ms long mdelay() between clearing and masking.
> 

The interrupt will not be lost if status bits change before masking interrupt.

> How frequent is this timeout? I guess lost interrupt is somehow nearly
> related to clearing, masking and unmasking if that cycle helps. One thing that
> comes to my mind is masking needed and could plain unmasking be also a
> working workaround?

Quite frequently.

> 
> Have you tried to print DW_IC_INTR_STAT, DW_IC_INTR_MASK and
> DW_IC_RAW_INTR_STAT when timeout occurs? E.g. just after printing the
> timeout out error in i2c_dw_xfer(). Probably good in i2c_dw_isr() too if if
> doesn't produce too much data and make debugging impossible.
> 

Yes, I have tried to print these status. I have confirmed the issue with hardware engineer. 

Re: [PATCH 1/1] I2C: designware: fix IO timeout issue for AMD controller

[Wolfram Sang]

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> > > > The driver disables TX interrupt when it is not needed anymore or
> > > > when TX gets aborted but the above will re-enable all interrupts
> > regardless.
> > > > Is that the intention?
> > > No, i2c controller can trigger next interrupt only after re-enable all interrupt.
> > 
> > If you get an error the function masks all interrupts and jumps to tx_aborted
> > label. With this patch you unmask all interrupts again before exiting the
> > function.
> > 
> 
> I see, how about change if statement to else if?

That sounds to me that a V2 is needed, or? Marking as "Changes
requested"...


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