[PATCH v2 v2 0/3] Extend dt bindings to support I2C on sifive devices and a fix broken IRQ in polling mode.

[PATCH v2 v2 0/3] Extend dt bindings to support I2C on sifive devices and a fix broken IRQ in polling mode.

[Sagar Shrikant Kadam]

The patch is based on mainline v5.1 and extends DT-bindings for Opencore based I2C device in FU540 
SoC, available on HiFive unleashed board (Rev A00), and also provides a workaround for broken IRQ
which affect I2C polling mode interface on FU540 chipsets. 

The polling mode workaround patch fixes the CPU stall issue, when-ever i2c transfer are initiated.

This workaround checks if it's a FU540 chipset based on device tree information, and check's for open
core's IF(interrupt flag) and TIP flags to break from the polling loop upon completion of transfer.

To test the patch, a PMOD-AD2 sensor is connected to HiFive Unleashed board over J1 connector, and 
appropriate device node is added into board specific device tree as per the information provided in 
dt-bindings in Documentation/devicetree/bindings/i2c/i2c-sifive.txt.
Without this workaround, the CPU stall's infinitely.

Busybox i2c utilities used to verify workaround : i2cdetect, i2cdump, i2cset, i2cget


Patch History:

V0<->V1:
-Incorporate review comments from Andrew
-Extend dt bindings into i2c-ocores.txt instead of adding new file
-Rename SIFIVE_FLAG_POLL to OCORES_FLAG_BROKEN_IRQ

V0:
-Update dt bindings for sifive i2c devices
-Fix broken IRQ affecting i2c polling mode interface.


Sagar Shrikant Kadam (3):
  dt-bindings: i2c: extend existing opencore bindings.
  i2c-ocore: sifive: add support for i2c device on FU540-c000 SoC.
  i2c-ocores: sifive: add polling mode workaround for FU540-C000 SoC.

 .../devicetree/bindings/i2c/i2c-ocores.txt         | 20 +++++++++++++
 drivers/i2c/busses/i2c-ocores.c                    | 33 +++++++++++++++++++---
 2 files changed, 49 insertions(+), 4 deletions(-)

-- 
1.9.1


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[PATCH v2 v2 1/3] dt-bindings: i2c: extend existing opencore bindings.

[Sagar Shrikant Kadam]

Add FU540-C000 specific device tree bindings to already
available i2-ocores file. This device is available on
HiFive Unleashed Rev A00 board.

Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
---
 Documentation/devicetree/bindings/i2c/i2c-ocores.txt | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
index 17bef9a..f6bcf90 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
@@ -2,6 +2,7 @@ Device tree configuration for i2c-ocores
 
 Required properties:
 - compatible      : "opencores,i2c-ocores" or "aeroflexgaisler,i2cmst"
+                    "sifive,fu540-c000-i2c" or "sifive,i2c0"
 - reg             : bus address start and address range size of device
 - interrupts      : interrupt number
 - clocks          : handle to the controller clock; see the note below.
@@ -67,3 +68,22 @@ or
 			reg = <0x60>;
 		};
 	};
+or
+	/*
+	  An Opencore based I2C node in FU540-C000 chip from SiFive
+	  This chip has a hardware erratum for broken IRQ
+	  so it's recommended not to define interrupt in the device node
+	*/
+	i2c@10030000 {
+			compatible = "sifive,i2c0","sifive,fu540-c000-i2c";
+			reg = <0x0 0x10030000 0x0 0x1000>;
+			reg-names = "i2c-control";
+			clocks = <&tlclk>;
+			clock-frequency = <100000>;
+
+			reg-shift = <2>;
+			reg-io-width = <1>;
+
+			#address-cells = <1>;
+			#size-cells = <0>;
+	};
-- 
1.9.1


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Re: [PATCH v2 v2 1/3] dt-bindings: i2c: extend existing opencore bindings.

[Andrew Lunn]

> +or
> +	/*
> +	  An Opencore based I2C node in FU540-C000 chip from SiFive
> +	  This chip has a hardware erratum for broken IRQ
> +	  so it's recommended not to define interrupt in the device node
> +	*/
> +	i2c@10030000 {
> +			compatible = "sifive,i2c0","sifive,fu540-c000-i2c";

The most specific compatible comes first.

You also need to be forward thinking. The next revision of the silicon
could have the bug fixed. You can then use plain "sifive,i2c0" to
indicate just polling is needed, not bug workaround. But for that to
work, you need "sifive,fu540-c000-i2c" first.

      Andrew

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Re: [PATCH v2 v2 1/3] dt-bindings: i2c: extend existing opencore bindings.

[Rob Herring]

On Tue, May 07, 2019 at 08:45:06PM +0530, Sagar Shrikant Kadam wrote:
> Add FU540-C000 specific device tree bindings to already
> available i2-ocores file. This device is available on
> HiFive Unleashed Rev A00 board.
> 
> Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
> ---
>  Documentation/devicetree/bindings/i2c/i2c-ocores.txt | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> index 17bef9a..f6bcf90 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> @@ -2,6 +2,7 @@ Device tree configuration for i2c-ocores
>  
>  Required properties:
>  - compatible      : "opencores,i2c-ocores" or "aeroflexgaisler,i2cmst"
> +                    "sifive,fu540-c000-i2c" or "sifive,i2c0"

If this is Opencores IP, does it really follow the Sifive versioning 
convention? If so, please reference sifive-blocks-ip-versioning.txt 
(which appears to have missed going upstream). Also, referencing the IP 
repository would be good too. If this IP block doesn't follow the same 
convention, then don't try using it for this binding.

>  - reg             : bus address start and address range size of device
>  - interrupts      : interrupt number
>  - clocks          : handle to the controller clock; see the note below.
> @@ -67,3 +68,22 @@ or
>  			reg = <0x60>;
>  		};
>  	};
> +or

Just a new compatible isn't really a reason to add an example.

> +	/*
> +	  An Opencore based I2C node in FU540-C000 chip from SiFive
> +	  This chip has a hardware erratum for broken IRQ
> +	  so it's recommended not to define interrupt in the device node

Then interrupts needs to be optional.

> +	*/
> +	i2c@10030000 {
> +			compatible = "sifive,i2c0","sifive,fu540-c000-i2c";
> +			reg = <0x0 0x10030000 0x0 0x1000>;
> +			reg-names = "i2c-control";

Not doucmented.

> +			clocks = <&tlclk>;
> +			clock-frequency = <100000>;
> +
> +			reg-shift = <2>;
> +			reg-io-width = <1>;
> +
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +	};
> -- 
> 1.9.1
> 
> 
> -- 
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Re: [PATCH v2 v2 1/3] dt-bindings: i2c: extend existing opencore bindings.

[Sagar Kadam]

Hello Rob,

Thank you for the review.

On Tue, May 14, 2019 at 2:26 AM Rob Herring <robh@kernel.org> wrote:
>
> On Tue, May 07, 2019 at 08:45:06PM +0530, Sagar Shrikant Kadam wrote:
> > Add FU540-C000 specific device tree bindings to already
> > available i2-ocores file. This device is available on
> > HiFive Unleashed Rev A00 board.
> >
> > Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
> > ---
> >  Documentation/devicetree/bindings/i2c/i2c-ocores.txt | 20 ++++++++++++++++++++
> >  1 file changed, 20 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> > index 17bef9a..f6bcf90 100644
> > --- a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> > @@ -2,6 +2,7 @@ Device tree configuration for i2c-ocores
> >
> >  Required properties:
> >  - compatible      : "opencores,i2c-ocores" or "aeroflexgaisler,i2cmst"
> > +                    "sifive,fu540-c000-i2c" or "sifive,i2c0"
>
> If this is Opencores IP, does it really follow the Sifive versioning
> convention? If so, please reference sifive-blocks-ip-versioning.txt
> (which appears to have missed going upstream). Also, referencing the IP
> repository would be good too. If this IP block doesn't follow the same
> convention, then don't try using it for this binding.
>
Yes, the sifive,fu540-c000-i2c is a SoC specific compatibility string,
this way SoC specific
workaround's or bugs, can be handled in the software and the ip-block
specific compatibility
string "sifive,<ip-block-name><integer version number>" i.e.
sifive,i2c0 is IP block specific compatibility
string. Please let me know if I need some correction here?
I will also update reference for sifive-blocks-ip-versioning and the
ip repository into next version of patch.

> >  - reg             : bus address start and address range size of device
> >  - interrupts      : interrupt number
> >  - clocks          : handle to the controller clock; see the note below.
> > @@ -67,3 +68,22 @@ or
> >                       reg = <0x60>;
> >               };
> >       };
> > +or
>
> Just a new compatible isn't really a reason to add an example.
>
> > +     /*
> > +       An Opencore based I2C node in FU540-C000 chip from SiFive
> > +       This chip has a hardware erratum for broken IRQ
> > +       so it's recommended not to define interrupt in the device node
>
> Then interrupts needs to be optional.
True, I will move interrupts and interrupt parent into optional section
>
> > +     */
> > +     i2c@10030000 {
> > +                     compatible = "sifive,i2c0","sifive,fu540-c000-i2c";
> > +                     reg = <0x0 0x10030000 0x0 0x1000>;
> > +                     reg-names = "i2c-control";
>
> Not doucmented.
In v1, I had added a new binding file as sifive-i2c-ocores.txt for
SiFive i2c core.
After Andrew's suggestion,  extending the available i2c-ocores.txt
seemed to be a better idea rather than adding a new file.
so added an example node which is HiFive specific in the existing file.
Please let me know if I need to handle this in a different way.

>
> > +                     clocks = <&tlclk>;
> > +                     clock-frequency = <100000>;
> > +
> > +                     reg-shift = <2>;
> > +                     reg-io-width = <1>;
> > +
> > +                     #address-cells = <1>;
> > +                     #size-cells = <0>;
> > +     };
> > --
> > 1.9.1
> >
> >
> > --
> > The information transmitted is intended only for the person or entity to
> > which it is addressed and may contain confidential and/or privileged
> > material. If you are not the intended recipient of this message please do
> > not read, copy, use or disclose this communication and notify the sender
> > immediately. It should be noted that any review, retransmission,
> > dissemination or other use of, or taking action or reliance upon, this
> > information by persons or entities other than the intended recipient is
> > prohibited

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Re: [PATCH v2 v2 1/3] dt-bindings: i2c: extend existing opencore bindings.

[Andrew Lunn]

> > > +     */
> > > +     i2c@10030000 {
> > > +                     compatible = "sifive,i2c0","sifive,fu540-c000-i2c";
> > > +                     reg = <0x0 0x10030000 0x0 0x1000>;
> > > +                     reg-names = "i2c-control";
> >
> > Not doucmented.
> In v1, I had added a new binding file as sifive-i2c-ocores.txt for
> SiFive i2c core.
> After Andrew's suggestion,  extending the available i2c-ocores.txt
> seemed to be a better idea rather than adding a new file.
> so added an example node which is HiFive specific in the existing file.
> Please let me know if I need to handle this in a different way.

Hi Sagar

Is reg-names actually needed?

   Andrew

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Re: [PATCH v2 v2 1/3] dt-bindings: i2c: extend existing opencore bindings.

[Rob Herring]

On Tue, May 14, 2019 at 7:50 AM Sagar Kadam <sagar.kadam@sifive.com> wrote:
>
> Hello Rob,
>
> Thank you for the review.
>
> On Tue, May 14, 2019 at 2:26 AM Rob Herring <robh@kernel.org> wrote:
> >
> > On Tue, May 07, 2019 at 08:45:06PM +0530, Sagar Shrikant Kadam wrote:
> > > Add FU540-C000 specific device tree bindings to already
> > > available i2-ocores file. This device is available on
> > > HiFive Unleashed Rev A00 board.
> > >
> > > Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
> > > ---
> > >  Documentation/devicetree/bindings/i2c/i2c-ocores.txt | 20 ++++++++++++++++++++
> > >  1 file changed, 20 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> > > index 17bef9a..f6bcf90 100644
> > > --- a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> > > +++ b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> > > @@ -2,6 +2,7 @@ Device tree configuration for i2c-ocores
> > >
> > >  Required properties:
> > >  - compatible      : "opencores,i2c-ocores" or "aeroflexgaisler,i2cmst"
> > > +                    "sifive,fu540-c000-i2c" or "sifive,i2c0"
> >
> > If this is Opencores IP, does it really follow the Sifive versioning
> > convention? If so, please reference sifive-blocks-ip-versioning.txt
> > (which appears to have missed going upstream). Also, referencing the IP
> > repository would be good too. If this IP block doesn't follow the same
> > convention, then don't try using it for this binding.
> >
> Yes, the sifive,fu540-c000-i2c is a SoC specific compatibility string,
> this way SoC specific
> workaround's or bugs, can be handled in the software and the ip-block
> specific compatibility
> string "sifive,<ip-block-name><integer version number>" i.e.
> sifive,i2c0 is IP block specific compatibility
> string. Please let me know if I need some correction here?
> I will also update reference for sifive-blocks-ip-versioning and the
> ip repository into next version of patch.

My question is whether I can correlate v0 to a specific revision of
the IP and versions will be tracked in the same way as SiFive IP
blocks?

> > >  - reg             : bus address start and address range size of device
> > >  - interrupts      : interrupt number
> > >  - clocks          : handle to the controller clock; see the note below.
> > > @@ -67,3 +68,22 @@ or
> > >                       reg = <0x60>;
> > >               };
> > >       };
> > > +or
> >
> > Just a new compatible isn't really a reason to add an example.
> >
> > > +     /*
> > > +       An Opencore based I2C node in FU540-C000 chip from SiFive
> > > +       This chip has a hardware erratum for broken IRQ
> > > +       so it's recommended not to define interrupt in the device node
> >
> > Then interrupts needs to be optional.
> True, I will move interrupts and interrupt parent into optional section
> >
> > > +     */
> > > +     i2c@10030000 {
> > > +                     compatible = "sifive,i2c0","sifive,fu540-c000-i2c";
> > > +                     reg = <0x0 0x10030000 0x0 0x1000>;
> > > +                     reg-names = "i2c-control";
> >
> > Not doucmented.
> In v1, I had added a new binding file as sifive-i2c-ocores.txt for
> SiFive i2c core.
> After Andrew's suggestion,  extending the available i2c-ocores.txt
> seemed to be a better idea rather than adding a new file.
> so added an example node which is HiFive specific in the existing file.
> Please let me know if I need to handle this in a different way.

That has nothing to do with whether reg-names is documented. Being in
the example is not documented. You either need to add it to the
property list or drop it from the example. IMO, you should drop it as
it is not necessary with only 1 entry.

Rob

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[PATCH v2 v2 2/3] i2c-ocore: sifive: add support for i2c device on FU540-c000 SoC.

[Sagar Shrikant Kadam]

Update device id table for Opencores I2C master used in HiFive Unleashed
platform having FU540-c000 chipset.

Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
---
 drivers/i2c/busses/i2c-ocores.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
index 4e1a077..7bf7b0c 100644
--- a/drivers/i2c/busses/i2c-ocores.c
+++ b/drivers/i2c/busses/i2c-ocores.c
@@ -85,6 +85,7 @@ struct ocores_i2c {
 
 #define TYPE_OCORES		0
 #define TYPE_GRLIB		1
+#define TYPE_SIFIVE_REV0	2
 
 static void oc_setreg_8(struct ocores_i2c *i2c, int reg, u8 value)
 {
@@ -465,6 +466,10 @@ static u32 ocores_func(struct i2c_adapter *adap)
 		.data = (void *)TYPE_OCORES,
 	},
 	{
+		.compatible = "sifive,fu540-c000-i2c",
+		.data = (void *)TYPE_SIFIVE_REV0,
+	},
+	{
 		.compatible = "aeroflexgaisler,i2cmst",
 		.data = (void *)TYPE_GRLIB,
 	},
-- 
1.9.1


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Re: [PATCH v2 v2 2/3] i2c-ocore: sifive: add support for i2c device on FU540-c000 SoC.

[Andrew Lunn]

On Tue, May 07, 2019 at 08:45:07PM +0530, Sagar Shrikant Kadam wrote:
> Update device id table for Opencores I2C master used in HiFive Unleashed
> platform having FU540-c000 chipset.
> 
> Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
> ---
>  drivers/i2c/busses/i2c-ocores.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
> index 4e1a077..7bf7b0c 100644
> --- a/drivers/i2c/busses/i2c-ocores.c
> +++ b/drivers/i2c/busses/i2c-ocores.c
> @@ -85,6 +85,7 @@ struct ocores_i2c {
>  
>  #define TYPE_OCORES		0
>  #define TYPE_GRLIB		1
> +#define TYPE_SIFIVE_REV0	2
>  
>  static void oc_setreg_8(struct ocores_i2c *i2c, int reg, u8 value)
>  {
> @@ -465,6 +466,10 @@ static u32 ocores_func(struct i2c_adapter *adap)
>  		.data = (void *)TYPE_OCORES,
>  	},
>  	{
> +		.compatible = "sifive,fu540-c000-i2c",
> +		.data = (void *)TYPE_SIFIVE_REV0,
> +	},

If you list "sifive,i2c0" in the binding document, it should be here
as well.

> +	{
>  		.compatible = "aeroflexgaisler,i2cmst",
>  		.data = (void *)TYPE_GRLIB,
>  	},
> -- 
> 1.9.1
> 
> 
> -- 
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> information by persons or entities other than the intended recipient is 
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[PATCH v2 v2 3/3] i2c-ocores: sifive: add polling mode workaround for FU540-C000 SoC.

[Sagar Shrikant Kadam]

The i2c-ocore driver already has a polling mode interface.But it needs
a workaround for FU540 Chipset on HiFive unleashed board (RevA00).
There is an erratum in FU540 chip that prevents interrupt driven i2c
transfers from working, and also the I2C controller's interrupt bit
cannot be cleared if set, due to this the existing i2c polling mode
interface added in mainline earlier doesn't work, and CPU stall's
infinitely, when-ever i2c transfer is initiated.

	commit 69c8c0c0efa8 ("i2c: ocores: add polling interface")

The workaround / fix under OCORES_FLAG_BROKEN_IRQ is particularly for
FU540-COOO SoC.

Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
---
 drivers/i2c/busses/i2c-ocores.c | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
index 7bf7b0c..8b994b4 100644
--- a/drivers/i2c/busses/i2c-ocores.c
+++ b/drivers/i2c/busses/i2c-ocores.c
@@ -27,6 +27,7 @@
 #include <linux/jiffies.h>
 
 #define OCORES_FLAG_POLL BIT(0)
+#define OCORES_FLAG_BROKEN_IRQ BIT(1)
 
 /*
  * 'process_lock' exists because ocores_process() and ocores_process_timeout()
@@ -239,8 +240,13 @@ static irqreturn_t ocores_isr(int irq, void *dev_id)
 	struct ocores_i2c *i2c = dev_id;
 	u8 stat = oc_getreg(i2c, OCI2C_STATUS);
 
-	if (!(stat & OCI2C_STAT_IF))
+	if (i2c->flags & OCORES_FLAG_BROKEN_IRQ) {
+		if (stat & OCI2C_STAT_IF)
+			if (!(stat & OCI2C_STAT_BUSY))
+				return IRQ_NONE;
+	} else if (!(stat & OCI2C_STAT_IF)) {
 		return IRQ_NONE;
+	}
 
 	ocores_process(i2c, stat);
 
@@ -356,6 +362,11 @@ static void ocores_process_polling(struct ocores_i2c *i2c)
 		ret = ocores_isr(-1, i2c);
 		if (ret == IRQ_NONE)
 			break; /* all messages have been transferred */
+		else {
+			if (i2c->flags & OCORES_FLAG_BROKEN_IRQ)
+				if (i2c->state == STATE_DONE)
+					break;
+		}
 	}
 }
 
@@ -406,7 +417,7 @@ static int ocores_xfer(struct i2c_adapter *adap,
 {
 	struct ocores_i2c *i2c = i2c_get_adapdata(adap);
 
-	if (i2c->flags & OCORES_FLAG_POLL)
+	if ((i2c->flags & (OCORES_FLAG_POLL | OCORES_FLAG_BROKEN_IRQ)))
 		return ocores_xfer_polling(adap, msgs, num);
 	return ocores_xfer_core(i2c, msgs, num, false);
 }
@@ -597,6 +608,7 @@ static int ocores_i2c_probe(struct platform_device *pdev)
 {
 	struct ocores_i2c *i2c;
 	struct ocores_i2c_platform_data *pdata;
+	const struct of_device_id *match;
 	struct resource *res;
 	int irq;
 	int ret;
@@ -678,13 +690,21 @@ static int ocores_i2c_probe(struct platform_device *pdev)
 
 	irq = platform_get_irq(pdev, 0);
 	if (irq == -ENXIO) {
-		i2c->flags |= OCORES_FLAG_POLL;
+		/*
+		 * Set a OCORES_FLAG_BROKEN_IRQ to enable workaround for FU540
+		 * in polling mode interface of i2c-ocore driver.
+		 */
+		match = of_match_node(ocores_i2c_match, pdev->dev.of_node);
+		if (match && (long)match->data == TYPE_SIFIVE_REV0)
+			i2c->flags |= OCORES_FLAG_BROKEN_IRQ;
+		else
+			i2c->flags |= OCORES_FLAG_POLL;
 	} else {
 		if (irq < 0)
 			return irq;
 	}
 
-	if (!(i2c->flags & OCORES_FLAG_POLL)) {
+	if (!(i2c->flags & (OCORES_FLAG_POLL | OCORES_FLAG_BROKEN_IRQ))) {
 		ret = devm_request_irq(&pdev->dev, irq, ocores_isr, 0,
 				       pdev->name, i2c);
 		if (ret) {
-- 
1.9.1


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Re: [PATCH v2 v2 0/3] Extend dt bindings to support I2C on sifive devices and a fix broken IRQ in polling mode.

[Andrew Lunn]

> The information transmitted is intended only for the person or entity to 
> which it is addressed and may contain confidential and/or privileged 
> material. If you are not the intended recipient of this message please do 
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You need to remove this. It is nonsense anyway. You are mailing to a
public list....

       Andrew

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