linux-kernel - Re: [PATCH v1] mfd: tps6586x: Move interrupt handling into workqueue

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Message-ID: <20180514123933.GI18312@ulmo>
Date:   Mon, 14 May 2018 14:39:33 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Lee Jones <lee.jones@...aro.org>,
        Jonathan Hunter <jonathanh@...dia.com>,
        linux-tegra@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] mfd: tps6586x: Move interrupt handling into workqueue

On Mon, May 14, 2018 at 03:20:55PM +0300, Dmitry Osipenko wrote:
> On 14.05.2018 15:01, Dmitry Osipenko wrote:
> > On 14.05.2018 14:51, Thierry Reding wrote:
> >> On Mon, May 14, 2018 at 12:18:42AM +0300, Dmitry Osipenko wrote:
> >>> Reading of status register within the interrupt handler fails with -EAGAIN
> >>> if I2C is busy with handling some other request at the same time. Move the
> >>> actual interrupt handling into a workqueue to avoid the unfortunate I2C
> >>> failure and to avoid hanging CPU in interrupt up to 1 second (transfer
> >>> timeout in the Tegra I2C driver).
> >>>
> >>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> >>> ---
> >>>  drivers/mfd/tps6586x.c | 40 +++++++++++++++++++++++++++++-----------
> >>>  1 file changed, 29 insertions(+), 11 deletions(-)
> >>
> >> Could this not be achieved with a threaded interrupt handler?
> >>
> >> Thierry
> >>
> > 
> > Seems yes. I completely forgot about the threaded interrupt handlers existence.
> > Thank you very much for the suggestion, I'll try with the threaded IRQ and send
> > v2 if it will be fine.
> > 
> 
> Oh wait! TPS6586x driver already uses threaded interrupt handler, so everything
> should be fine in regards to the interrupt handling and this patch is obsolete.
> Thank you again for the good suggestion, then it's only the Tegra's I2C driver
> that causes trouble for the TPS6586x right now.

Heh... indeed. Sounds like the discussion that Wolfram pointed out is
the right way forward.

Thierry

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