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[217.229.16.64]) by smtp.gmail.com with ESMTPSA id c65sm11302143wma.24.2019.02.03.23.54.55 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sun, 03 Feb 2019 23:54:55 -0800 (PST) Date: Mon, 4 Feb 2019 08:54:54 +0100 From: Thierry Reding To: Sowjanya Komatineni Cc: Dmitry Osipenko , Jonathan Hunter , Mantravadi Karthik , Shardar Mohammed , Timo Alho , "linux-tegra@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-i2c@vger.kernel.org" Subject: Re: [PATCH V9 4/5] i2c: tegra: update transfer timeout Message-ID: <20190204075454.GA19087@ulmo> References: <1549040867-18149-1-git-send-email-skomatineni@nvidia.com> <1549040867-18149-4-git-send-email-skomatineni@nvidia.com> <53b3f00f-b3a8-e1ef-b04b-1bdd5f5473ce@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="h31gzZEtNLTqOjlF" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --h31gzZEtNLTqOjlF Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Feb 01, 2019 at 07:37:45PM +0000, Sowjanya Komatineni wrote: >=20 > > > BYTES_PER_FIFO_WORD 4 > > > =20 > > > #define I2C_CNFG 0x000 > > > @@ -893,8 +892,9 @@ static int tegra_i2c_issue_bus_clear(struct tegra= _i2c_dev *i2c_dev) > > > i2c_writel(i2c_dev, reg, I2C_BUS_CLEAR_CNFG); > > > tegra_i2c_unmask_irq(i2c_dev, I2C_INT_BUS_CLR_DONE); > > > =20 > > > - time_left =3D wait_for_completion_timeout(&i2c_dev->msg_complete, > > > - TEGRA_I2C_TIMEOUT); > > > + time_left =3D wait_for_completion_timeout( > > > + &i2c_dev->msg_complete, > > > + msecs_to_jiffies(1000)); > > > > So potentially tegra_i2c_xfer_msg() could take more than 1 second > > and then fail with -EAGAIN, correct? In that case we should set > > adapter.timeout in probe to a larger value: > > > Bus clear pulse threshold we are setting is 9 (default as per spec) so > bus clear should happen after finishing sending of 9 pulses. > So 1sec is very long time for bus to get released and in case of ARB > LOST whole transfer to return EAGAIN will be much less then 1sec What if for example we have a very long transfer, say some 64 KiB on Tegra194 and about 95% through the transfer something causes the bus to lock up. The transfer so far would've taken something on the order of 5 seconds, but we'd still fail, potentially with -EAGAIN, right? Or is there some other mechanism that would prevent the above from happening? 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