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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID:
 <DM4PR12MB6109784A362751CEE8D472B78C08A@DM4PR12MB6109.namprd12.prod.outlook.com>
Date: Fri, 12 Sep 2025 06:55:41 +0000
From: "Guntupalli, Manikanta" <manikanta.guntupalli@....com>
To: "git (AMD-Xilinx)" <git@....com>, "Simek, Michal" <michal.simek@....com>,
	"peda@...ntia.se" <peda@...ntia.se>, "linux-i2c@...r.kernel.org"
	<linux-i2c@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "wsa+renesas@...g-engineering.com"
	<wsa+renesas@...g-engineering.com>
CC: "Pandey, Radhey Shyam" <radhey.shyam.pandey@....com>, "Goud, Srinivas"
	<srinivas.goud@....com>, "Datta, Shubhrajyoti" <shubhrajyoti.datta@....com>,
	"manion05gk@...il.com" <manion05gk@...il.com>
Subject: RE: [PATCH V2] PCA9541: Use I2C adapter timeout value for arbitration
 timeout

[Public]

Ping!

> -----Original Message-----
> From: Guntupalli, Manikanta
> Sent: Monday, September 1, 2025 11:18 AM
> To: Manikanta Guntupalli <manikanta.guntupalli@....com>; git (AMD-Xilinx)
> <git@....com>; Simek, Michal <michal.simek@....com>; peda@...ntia.se;
> linux-i2c@...r.kernel.org; linux-kernel@...r.kernel.org; wsa+renesas@...g-
> engineering.com
> Cc: Pandey, Radhey Shyam <radhey.shyam.pandey@....com>; Goud, Srinivas
> <srinivas.goud@....com>; Datta, Shubhrajyoti <shubhrajyoti.datta@....com>;
> manion05gk@...il.com
> Subject: RE: [PATCH V2] PCA9541: Use I2C adapter timeout value for arbitration
> timeout
>
> Ping!
>
> > -----Original Message-----
> > From: Manikanta Guntupalli <manikanta.guntupalli@....com>
> > Sent: Thursday, July 31, 2025 6:26 PM
> > To: git (AMD-Xilinx) <git@....com>; Simek, Michal
> > <michal.simek@....com>; peda@...ntia.se; linux-i2c@...r.kernel.org;
> > linux-kernel@...r.kernel.org;
> > wsa+renesas@...g-engineering.com
> > Cc: Pandey, Radhey Shyam <radhey.shyam.pandey@....com>; Goud, Srinivas
> > <srinivas.goud@....com>; Datta, Shubhrajyoti
> > <shubhrajyoti.datta@....com>; manion05gk@...il.com; Guntupalli,
> > Manikanta <manikanta.guntupalli@....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@....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@....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.