linux-kernel - Re: [PATCH] i2c: cadence: Increase timeout per message if necessary

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Date:   Wed, 23 Mar 2022 12:02:08 +0100
From:   Michal Simek <michal.simek@...inx.com>
To:     <tanureal@...nsource.cirrus.com>,
        Michal Simek <michal.simek@...inx.com>,
        Shubhrajyoti Datta <shubhrajyoti.datta@...inx.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-i2c@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <patches@...nsource.cirrus.com>
Subject: Re: [PATCH] i2c: cadence: Increase timeout per message if necessary



On 3/23/22 11:07, tanureal@...nsource.cirrus.com wrote:
> On 3/22/22 5:18 PM, Michal Simek <michal.simek@...inx.com> wrote:
>>
>>
>> On 3/22/22 16:34, tanureal@...nsource.cirrus.com wrote:
>> > On 3/21/22 3:57 PM, Michal Simek <michal.simek@...inx.com> wrote:
>> >> +Shubhrajyoti
>> >>
>> >> On 3/9/22 10:31, Lucas Tanure wrote:
>> >> > Timeout as 1 second sets a upper limit on the length of
>> >> > the transfer executed, but there is no maximum length of
>> >> > a write or read message set in i2c_adapter_quirks for this
>> >> > controller.
>> >>
>> >> nit: I would expect that you have run any test and you reached an issue.
>> >> Would be good to describe what exactly you have tried on which >> 
>> configuration to make it super clear.
>> >>
>> >> >
>> >> > To remove that limitation calculate the minimal time
>> >> > necessary, plus some wiggle room, for every message
>> >> > and use it instead of the default one second, if
>> >> > more than one second.
>> >> >
>> >> > Signed-off-by: Lucas Tanure <tanureal@...nsource.cirrus.com>
>> >> > ---
>> >> >   drivers/i2c/busses/i2c-cadence.c | 12 ++++++++++--
>> >> >   1 file changed, 10 insertions(+), 2 deletions(-)
>> >> >
>> >> > diff --git a/drivers/i2c/busses/i2c-cadence.c > >> 
>> b/drivers/i2c/busses/i2c-cadence.c
>> >> > index 805c77143a0f..b4c1ad19cdae 100644
>> >> > --- a/drivers/i2c/busses/i2c-cadence.c
>> >> > +++ b/drivers/i2c/busses/i2c-cadence.c
>> >> > @@ -760,7 +760,7 @@ static void cdns_i2c_master_reset(struct > >> 
>> i2c_adapter *adap)
>> >> >   static int cdns_i2c_process_msg(struct cdns_i2c *id, struct >> i2c_msg 
>> > *msg,
>> >> >           struct i2c_adapter *adap)
>> >> >   {
>> >> > -    unsigned long time_left;
>> >> > +    unsigned long time_left, msg_timeout;
>> >> >       u32 reg;
>> >> >       id->p_msg = msg;
>> >> > @@ -785,8 +785,16 @@ static int cdns_i2c_process_msg(struct >> cdns_i2c > 
>> *id, struct i2c_msg *msg,
>> >> >       else
>> >> >           cdns_i2c_msend(id);
>> >> > +    /* Minimal time to execute this message */
>> >> > +    msg_timeout = msecs_to_jiffies((1000 * msg->len * >> BITS_PER_BYTE) 
>> > / id->i2c_clk);
>> >> > +    /* Plus some wiggle room */
>> >> > +    msg_timeout += msecs_to_jiffies(500);
>> >> > +
>> >> > +    if (msg_timeout < adap->timeout)
>> >> > +        msg_timeout = adap->timeout;
>> >> > +
>> >> >       /* Wait for the signal of completion */
>> >> > -    time_left = wait_for_completion_timeout(&id->xfer_done, > >> 
>> adap->timeout);
>> >> > +    time_left = wait_for_completion_timeout(&id->xfer_done, > >> 
>> msg_timeout);
>> >> >       if (time_left == 0) {
>> >> >           cdns_i2c_master_reset(adap);
>> >> >           dev_err(id->adap.dev.parent,
>> >>
>> >>
>> >> If my assumption is right and there is any actual issue you had >> please 
>> send v2 and feel free to add there my:
>> >> Acked-by: Michal Simek <michal.simek@...inx.com>
>> >>
>> >> Thanks,
>> >> Michal
>> >>
>> >>
>> >>
>> > The issue happens for I2C devices that have firmware, which will send > a 
>> big I2C message, but the I2C controller will timeout on it.
>> > That happened for CS35L41 DSP firmware tests, so no particular > 
>> configuration, just a driver sending firmware blob over I2C.
>>
>> How big is it?
>>
>> M
>>
> The firmware has 33868 bytes, and it is split in a few writes. The first one to 
> time out has 20240 bytes:
> 
> [   53.398444] cs35l41 0-0040: DSP1: Firmware version: 3
> [   53.403522] cs35l41 0-0040: DSP1: cs35l41-dsp1-spk-prot.wmfw: Fri 04 Feb 2022 
> 12:01:42 W. Europe Standard Time
> [   55.331688] cdns-i2c e0004000.i2c: timeout waiting on completion
> [   55.336721] cs35l41 0-0040: DSP1: cs35l41-dsp1-spk-prot.wmfw.5: Failed to 
> write 20240 bytes at 0 in PM_PACKED: -110
> 
> 20240 bytes at 100k clock should take 1.6192 seconds, which is more than the 
> current timeout of one second.

ok.

thanks,
Michal