[PATCH V2] PCA9541: Use I2C adapter timeout value for arbitration timeout

[PATCH V2] PCA9541: Use I2C adapter timeout value for arbitration timeout

[Manikanta Guntupalli]

Remove existing arbitration timeout macros and use I2C adapter timeout
value for arbitration timeout and forceful bus ownership.

I2C adapter timeout can be configurable from user space, so using it
for arbitration timeout helps in configuring the arbitration timeout
from user space depending on the use case.

Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
---
Changes for V2:
Remove existing arbitration timeout macros and use i2c adapter timeout
value.
Change logging and commit details.
Link for V1: https://lore.kernel.org/all/20250711124503.3390451-1-manikanta.guntupalli@amd.com/
---
 drivers/i2c/muxes/i2c-mux-pca9541.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/muxes/i2c-mux-pca9541.c b/drivers/i2c/muxes/i2c-mux-pca9541.c
index 8663c8a7c269..3d8002caf703 100644
--- a/drivers/i2c/muxes/i2c-mux-pca9541.c
+++ b/drivers/i2c/muxes/i2c-mux-pca9541.c
@@ -63,10 +63,6 @@
 #define mybus(x)	(!((x) & MYBUS) || ((x) & MYBUS) == MYBUS)
 #define busoff(x)	(!((x) & BUSON) || ((x) & BUSON) == BUSON)
 
-/* arbitration timeouts, in jiffies */
-#define ARB_TIMEOUT	(HZ / 8)	/* 125 ms until forcing bus ownership */
-#define ARB2_TIMEOUT	(HZ / 4)	/* 250 ms until acquisition failure */
-
 /* arbitration retry delays, in us */
 #define SELECT_DELAY_SHORT	50
 #define SELECT_DELAY_LONG	1000
@@ -229,6 +225,9 @@ static int pca9541_arbitrate(struct i2c_client *client)
 		 */
 		data->select_timeout = SELECT_DELAY_LONG;
 		if (time_is_before_eq_jiffies(data->arb_timeout)) {
+			dev_warn(&client->dev,
+				 "Arbitration timeout on I2C bus, forcing bus ownership\n");
+
 			/* Time is up, take the bus and reset it. */
 			pca9541_reg_write(client,
 					  PCA9541_CONTROL,
@@ -251,10 +250,10 @@ static int pca9541_select_chan(struct i2c_mux_core *muxc, u32 chan)
 	struct pca9541 *data = i2c_mux_priv(muxc);
 	struct i2c_client *client = data->client;
 	int ret;
-	unsigned long timeout = jiffies + ARB2_TIMEOUT;
+	unsigned long timeout = jiffies + (2 * client->adapter->timeout);
 		/* give up after this time */
 
-	data->arb_timeout = jiffies + ARB_TIMEOUT;
+	data->arb_timeout = jiffies + client->adapter->timeout;
 		/* force bus ownership after this time */
 
 	do {
@@ -267,6 +266,7 @@ static int pca9541_select_chan(struct i2c_mux_core *muxc, u32 chan)
 		else
 			msleep(data->select_timeout / 1000);
 	} while (time_is_after_eq_jiffies(timeout));
+	dev_warn(&client->dev, "Failed to acquire I2C bus, timed out\n");
 
 	return -ETIMEDOUT;
 }
-- 
2.34.1

RE: [PATCH V2] PCA9541: Use I2C adapter timeout value for arbitration timeout

[Guntupalli, Manikanta]

[Public]

Ping!

> -----Original Message-----
> From: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
> Sent: Thursday, July 31, 2025 6:26 PM
> To: git (AMD-Xilinx) <git@amd.com>; Simek, Michal <michal.simek@amd.com>;
> peda@axentia.se; linux-i2c@vger.kernel.org; linux-kernel@vger.kernel.org;
> wsa+renesas@sang-engineering.com
> Cc: Pandey, Radhey Shyam <radhey.shyam.pandey@amd.com>; Goud, Srinivas
> <srinivas.goud@amd.com>; Datta, Shubhrajyoti <shubhrajyoti.datta@amd.com>;
> manion05gk@gmail.com; Guntupalli, Manikanta <manikanta.guntupalli@amd.com>
> Subject: [PATCH V2] PCA9541: Use I2C adapter timeout value for arbitration
> timeout
>
> Remove existing arbitration timeout macros and use I2C adapter timeout
> value for arbitration timeout and forceful bus ownership.
>
> I2C adapter timeout can be configurable from user space, so using it
> for arbitration timeout helps in configuring the arbitration timeout
> from user space depending on the use case.
>
> Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
> ---
> Changes for V2:
> Remove existing arbitration timeout macros and use i2c adapter timeout
> value.
> Change logging and commit details.
> Link for V1: https://lore.kernel.org/all/20250711124503.3390451-1-
> manikanta.guntupalli@amd.com/
> ---
>  drivers/i2c/muxes/i2c-mux-pca9541.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/i2c/muxes/i2c-mux-pca9541.c b/drivers/i2c/muxes/i2c-mux-
> pca9541.c
> index 8663c8a7c269..3d8002caf703 100644
> --- a/drivers/i2c/muxes/i2c-mux-pca9541.c
> +++ b/drivers/i2c/muxes/i2c-mux-pca9541.c
> @@ -63,10 +63,6 @@
>  #define mybus(x)     (!((x) & MYBUS) || ((x) & MYBUS) == MYBUS)
>  #define busoff(x)    (!((x) & BUSON) || ((x) & BUSON) == BUSON)
>
> -/* arbitration timeouts, in jiffies */
> -#define ARB_TIMEOUT  (HZ / 8)        /* 125 ms until forcing bus ownership */
> -#define ARB2_TIMEOUT (HZ / 4)        /* 250 ms until acquisition failure */
> -
>  /* arbitration retry delays, in us */
>  #define SELECT_DELAY_SHORT   50
>  #define SELECT_DELAY_LONG    1000
> @@ -229,6 +225,9 @@ static int pca9541_arbitrate(struct i2c_client *client)
>                */
>               data->select_timeout = SELECT_DELAY_LONG;
>               if (time_is_before_eq_jiffies(data->arb_timeout)) {
> +                     dev_warn(&client->dev,
> +                              "Arbitration timeout on I2C bus, forcing bus
> ownership\n");
> +
>                       /* Time is up, take the bus and reset it. */
>                       pca9541_reg_write(client,
>                                         PCA9541_CONTROL,
> @@ -251,10 +250,10 @@ static int pca9541_select_chan(struct i2c_mux_core
> *muxc, u32 chan)
>       struct pca9541 *data = i2c_mux_priv(muxc);
>       struct i2c_client *client = data->client;
>       int ret;
> -     unsigned long timeout = jiffies + ARB2_TIMEOUT;
> +     unsigned long timeout = jiffies + (2 * client->adapter->timeout);
>               /* give up after this time */
>
> -     data->arb_timeout = jiffies + ARB_TIMEOUT;
> +     data->arb_timeout = jiffies + client->adapter->timeout;
>               /* force bus ownership after this time */
>
>       do {
> @@ -267,6 +266,7 @@ static int pca9541_select_chan(struct i2c_mux_core *muxc,
> u32 chan)
>               else
>                       msleep(data->select_timeout / 1000);
>       } while (time_is_after_eq_jiffies(timeout));
> +     dev_warn(&client->dev, "Failed to acquire I2C bus, timed out\n");
>
>       return -ETIMEDOUT;
>  }
> --
> 2.34.1

Thanks,
Manikanta.

RE: [PATCH V2] PCA9541: Use I2C adapter timeout value for arbitration timeout

[Guntupalli, Manikanta]

[Public]

Ping!

> -----Original Message-----
> From: Guntupalli, Manikanta
> Sent: Monday, September 1, 2025 11:18 AM
> To: Manikanta Guntupalli <manikanta.guntupalli@amd.com>; git (AMD-Xilinx)
> <git@amd.com>; Simek, Michal <michal.simek@amd.com>; peda@axentia.se;
> linux-i2c@vger.kernel.org; linux-kernel@vger.kernel.org; wsa+renesas@sang-
> engineering.com
> Cc: Pandey, Radhey Shyam <radhey.shyam.pandey@amd.com>; Goud, Srinivas
> <srinivas.goud@amd.com>; Datta, Shubhrajyoti <shubhrajyoti.datta@amd.com>;
> manion05gk@gmail.com
> Subject: RE: [PATCH V2] PCA9541: Use I2C adapter timeout value for arbitration
> timeout
>
> Ping!
>
> > -----Original Message-----
> > From: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
> > Sent: Thursday, July 31, 2025 6:26 PM
> > To: git (AMD-Xilinx) <git@amd.com>; Simek, Michal
> > <michal.simek@amd.com>; peda@axentia.se; linux-i2c@vger.kernel.org;
> > linux-kernel@vger.kernel.org;
> > wsa+renesas@sang-engineering.com
> > Cc: Pandey, Radhey Shyam <radhey.shyam.pandey@amd.com>; Goud, Srinivas
> > <srinivas.goud@amd.com>; Datta, Shubhrajyoti
> > <shubhrajyoti.datta@amd.com>; manion05gk@gmail.com; Guntupalli,
> > Manikanta <manikanta.guntupalli@amd.com>
> > Subject: [PATCH V2] PCA9541: Use I2C adapter timeout value for
> > arbitration timeout
> >
> > Remove existing arbitration timeout macros and use I2C adapter timeout
> > value for arbitration timeout and forceful bus ownership.
> >
> > I2C adapter timeout can be configurable from user space, so using it
> > for arbitration timeout helps in configuring the arbitration timeout
> > from user space depending on the use case.
> >
> > Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
> > ---
> > Changes for V2:
> > Remove existing arbitration timeout macros and use i2c adapter timeout
> > value.
> > Change logging and commit details.
> > Link for V1: https://lore.kernel.org/all/20250711124503.3390451-1-
> > manikanta.guntupalli@amd.com/
> > ---
> >  drivers/i2c/muxes/i2c-mux-pca9541.c | 12 ++++++------
> >  1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/i2c/muxes/i2c-mux-pca9541.c
> > b/drivers/i2c/muxes/i2c-mux- pca9541.c index
> > 8663c8a7c269..3d8002caf703 100644
> > --- a/drivers/i2c/muxes/i2c-mux-pca9541.c
> > +++ b/drivers/i2c/muxes/i2c-mux-pca9541.c
> > @@ -63,10 +63,6 @@
> >  #define mybus(x)   (!((x) & MYBUS) || ((x) & MYBUS) == MYBUS)
> >  #define busoff(x)  (!((x) & BUSON) || ((x) & BUSON) == BUSON)
> >
> > -/* arbitration timeouts, in jiffies */
> > -#define ARB_TIMEOUT        (HZ / 8)        /* 125 ms until forcing bus ownership */
> > -#define ARB2_TIMEOUT       (HZ / 4)        /* 250 ms until acquisition failure */
> > -
> >  /* arbitration retry delays, in us */
> >  #define SELECT_DELAY_SHORT 50
> >  #define SELECT_DELAY_LONG  1000
> > @@ -229,6 +225,9 @@ static int pca9541_arbitrate(struct i2c_client *client)
> >              */
> >             data->select_timeout = SELECT_DELAY_LONG;
> >             if (time_is_before_eq_jiffies(data->arb_timeout)) {
> > +                   dev_warn(&client->dev,
> > +                            "Arbitration timeout on I2C bus, forcing bus
> > ownership\n");
> > +
> >                     /* Time is up, take the bus and reset it. */
> >                     pca9541_reg_write(client,
> >                                       PCA9541_CONTROL,
> > @@ -251,10 +250,10 @@ static int pca9541_select_chan(struct
> > i2c_mux_core *muxc, u32 chan)
> >     struct pca9541 *data = i2c_mux_priv(muxc);
> >     struct i2c_client *client = data->client;
> >     int ret;
> > -   unsigned long timeout = jiffies + ARB2_TIMEOUT;
> > +   unsigned long timeout = jiffies + (2 * client->adapter->timeout);
> >             /* give up after this time */
> >
> > -   data->arb_timeout = jiffies + ARB_TIMEOUT;
> > +   data->arb_timeout = jiffies + client->adapter->timeout;
> >             /* force bus ownership after this time */
> >
> >     do {
> > @@ -267,6 +266,7 @@ static int pca9541_select_chan(struct i2c_mux_core
> > *muxc,
> > u32 chan)
> >             else
> >                     msleep(data->select_timeout / 1000);
> >     } while (time_is_after_eq_jiffies(timeout));
> > +   dev_warn(&client->dev, "Failed to acquire I2C bus, timed out\n");
> >
> >     return -ETIMEDOUT;
> >  }
> > --
> > 2.34.1
>

Thanks,
Manikanta.

Re: [PATCH V2] PCA9541: Use I2C adapter timeout value for arbitration timeout

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 622 bytes --]

On Thu, Jul 31, 2025 at 06:25:35PM +0530, Manikanta Guntupalli wrote:
> Remove existing arbitration timeout macros and use I2C adapter timeout
> value for arbitration timeout and forceful bus ownership.
> 
> I2C adapter timeout can be configurable from user space, so using it
> for arbitration timeout helps in configuring the arbitration timeout
> from user space depending on the use case.
> 
> Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com>

Please use 'git log' to check proper prefix for subject like "i2c: mux:
pca9541". Fixed it for you this time.

Applied to for-next, thanks!


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