From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH 2/3] i2c/pxa: only define 'blue_murder'-function if DEBUG is #defined Date: Sun, 18 Apr 2010 15:22:51 +0200 Message-ID: <20100418132251.GB21364@pengutronix.de> References: <20100224110044.GB15181@pengutronix.de> <1267009306-17227-2-git-send-email-u.kleine-koenig@pengutronix.de> <20100228155502.GB16745@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="7ZAtKRhVyVSsbBD2" Return-path: Content-Disposition: inline In-Reply-To: <20100228155502.GB16745-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Russell King - ARM Linux Cc: Uwe =?iso-8859-15?Q?Kleine-K=F6nig?= , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Ben Dooks , Pavel Machek , Roel Kluin , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: linux-i2c@vger.kernel.org --7ZAtKRhVyVSsbBD2 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Sorry to bump this old thread, it dropped off my todo-list :( On Sun, Feb 28, 2010 at 03:55:02PM +0000, Russell King - ARM Linux wrote: > On Wed, Feb 24, 2010 at 12:01:45PM +0100, Uwe Kleine-K=F6nig wrote: > > From: Wolfram Sang > >=20 > > This talkative function is also called on timeouts. As timeouts can > > happen on regular writes to EEPROMs (no error case), this creates false > > positives. Giving lots of details is interesting only for developers > > anyhow, so just use the function if DEBUG is #defined. >=20 > Are you sure this is safe? If you time out the write before it completes, > how do you know if the write was successful? >=20 > I don't think this is "no error code" nor "false positive". If the timeo= ut > is too short for your EEPROMs, then the timeout needs to be increased. I am sure this is safe because we have retries. The eeprom driver first tri= es to write data without a delay, because EEPROMs often have buffers. Once the buffers are full, the chip will not answer to the next write request which = will result in a timeout for this write request. This is expected, so it will be retried after some delay. Something like -EBUSY. Only if another "outer" timeout passed after some retries, then we have a problem and this should be user visible. But the timeout for the write request is nothing exceptional = and the user doesn't need to be informed about it, especially not in this detai= l. This is what the patch is addressing. Kind regards, Wolfram --=20 Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | --7ZAtKRhVyVSsbBD2 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEARECAAYFAkvLB6sACgkQD27XaX1/VRtCBQCeJOtzw7shQQA99eMRDv7/fguO /mUAoJxN7wyGOxM0DiwNvOzPl8aUGs/i =qrgG -----END PGP SIGNATURE----- --7ZAtKRhVyVSsbBD2--