From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH]mmc: sdhci: use udelay instead of mdelay for some cases Date: Thu, 27 Oct 2011 07:15:32 +0200 Message-ID: <20111027051532.GA28387@pengutronix.de> References: <20111027041851.GA18442@gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="yrj/dFKFPuw6o+aM" Return-path: Received: from metis.ext.pengutronix.de ([92.198.50.35]:50360 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750837Ab1J0FPe (ORCPT ); Thu, 27 Oct 2011 01:15:34 -0400 Content-Disposition: inline In-Reply-To: <20111027041851.GA18442@gmail.com> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: "Shawn.Dong" Cc: linux-mmc@vger.kernel.org --yrj/dFKFPuw6o+aM Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, On Thu, Oct 27, 2011 at 12:18:53PM +0800, Shawn.Dong wrote: > sdhci_set_clock or sdhci_reset or sdhci_send_command may be used in > critical region which is protected by spin_lock_irqsave. Thus, these > functions will delay the responsing of the kernel interrupts. Yes, so this needs to be improved, not the delay values. > So in this case, using a mdelay will cause unnecessary latency. Our > hardware, in most case will not cause 1ms to finish its job. Using > udelay instead can reduce it. Could you guarantee this for all other SDHCI hardware out there as well? Regards, Wolfram --=20 Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | --yrj/dFKFPuw6o+aM Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEARECAAYFAk6o6PQACgkQD27XaX1/VRvFBACfc4OrmQDtgv6Fy9v8R4tV/9UC 1KcAn1jLvjEHeKFwRkoSGfoXmt6a1nMn =s/W+ -----END PGP SIGNATURE----- --yrj/dFKFPuw6o+aM--