From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [92.198.50.35]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 6FB32B714E for ; Sat, 4 Sep 2010 02:02:14 +1000 (EST) Date: Fri, 3 Sep 2010 18:02:09 +0200 From: Wolfram Sang To: Eric Millbrandt Subject: Re: [PATCH] powerpc/5200: tighten up ac97 reset timing Message-ID: <20100903160209.GE4813@pengutronix.de> References: <1283528722-15644-1-git-send-email-emillbrandt@dekaresearch.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="JBi0ZxuS5uaEhkUZ" In-Reply-To: <1283528722-15644-1-git-send-email-emillbrandt@dekaresearch.com> Cc: linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --JBi0ZxuS5uaEhkUZ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Sep 03, 2010 at 11:45:22AM -0400, Eric Millbrandt wrote: > Tighten up time timing around the gpio reset functionality. Add a 200ns > delay before remuxing the pins back to ac97 to comply with the ac97 spec. > This delay ensures that sync and sdata_out are held low while reset > transitions to high. >=20 > Signed-off-by: Eric Millbrandt > --- >=20 > Scope shots are availible upon request. >=20 > arch/powerpc/platforms/52xx/mpc52xx_common.c | 5 ++++- > 1 files changed, 4 insertions(+), 1 deletions(-) >=20 > diff --git a/arch/powerpc/platforms/52xx/mpc52xx_common.c b/arch/powerpc/= platforms/52xx/mpc52xx_common.c > index 6e90531..79adfe7 100644 > --- a/arch/powerpc/platforms/52xx/mpc52xx_common.c > +++ b/arch/powerpc/platforms/52xx/mpc52xx_common.c > @@ -326,11 +326,14 @@ int mpc5200_psc_ac97_gpio_reset(int psc_number) > clrbits8(&wkup_gpio->wkup_dvo, reset); >=20 > /* wait at lease 1 us */ Maybe you could fix this typo as well while you are here? > - udelay(2); > + udelay(1); >=20 > /* Deassert reset */ > setbits8(&wkup_gpio->wkup_dvo, reset); >=20 > + /* wait at least 200ns */ > + __delay(7); ndelay(200)? > + > /* Restore pin-muxing */ > out_be32(&simple_gpio->port_config, mux); >=20 > -- > 1.6.3.1 >=20 > -DISCLAIMER: an automatically appended disclaimer may follow. By posting- > -to a public e-mail mailing list I hereby grant permission to distribute- > -and copy this message.- >=20 > This e-mail and the information, including any attachments, it contains a= re intended to be a confidential communication only to the person or entity= to whom it is addressed and may contain information that is privileged. If= the reader of this message is not the intended recipient, you are hereby n= otified that any dissemination, distribution or copying of this communicati= on is strictly prohibited. If you have received this communication in error= , please immediately notify the sender and destroy the original message. >=20 > Thank you. >=20 > Please consider the environment before printing this email. > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev --=20 Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | --JBi0ZxuS5uaEhkUZ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iEYEARECAAYFAkyBHAEACgkQD27XaX1/VRtIuQCeIpRBKb5c70zvmIL9lnUzcS/s YIEAni8BSTNo9lP57hIC0ke9ytlWebiJ =7ept -----END PGP SIGNATURE----- --JBi0ZxuS5uaEhkUZ--