Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753213AbaFDNP7 (ORCPT ); Wed, 4 Jun 2014 09:15:59 -0400 Received: from mail-we0-f179.google.com ([74.125.82.179]:54392 "EHLO mail-we0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752534AbaFDNP4 (ORCPT ); Wed, 4 Jun 2014 09:15:56 -0400 Date: Wed, 4 Jun 2014 15:13:07 +0200 From: Thierry Reding To: Vivek Gautam Cc: Linux USB Mailing List , "linux-samsung-soc@vger.kernel.org" , linux-tegra , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Greg KH , Alan Stern , Stephen Warren , Kukjin Kim , Alexander Shiyan Subject: Re: [PATCH v2 6/6] usb: host: ohci-exynos: Use devm_ioremap_resource instead of devm_ioremap Message-ID: <20140604131306.GB28484@ulmo> References: <1399723210-21569-1-git-send-email-gautam.vivek@samsung.com> <1399723210-21569-7-git-send-email-gautam.vivek@samsung.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="7ZAtKRhVyVSsbBD2" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --7ZAtKRhVyVSsbBD2 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jun 04, 2014 at 03:41:20PM +0530, Vivek Gautam wrote: > Hi, >=20 >=20 > On Sat, May 10, 2014 at 5:30 PM, Vivek Gautam = wrote: > > Using devm_ioremap_resource() API should actually be preferred over > > devm_ioremap(), since the former request the mem region first and then > > gives back the ioremap'ed memory pointer. > > devm_ioremap_resource() calls request_mem_region(), therby preventing > > other drivers to make any overlapping call to the same region. > > > > Signed-off-by: Vivek Gautam >=20 > Although this patch and rest in the series are merged. > But i have got a doubt, so making this thread alive. >=20 > > --- > > drivers/usb/host/ohci-exynos.c | 7 +++---- > > 1 file changed, 3 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/usb/host/ohci-exynos.c b/drivers/usb/host/ohci-exy= nos.c > > index 9cf80cb..dec691d 100644 > > --- a/drivers/usb/host/ohci-exynos.c > > +++ b/drivers/usb/host/ohci-exynos.c > > @@ -120,10 +120,9 @@ skip_phy: > > > > hcd->rsrc_start =3D res->start; > > hcd->rsrc_len =3D resource_size(res); > > - hcd->regs =3D devm_ioremap(&pdev->dev, res->start, hcd->rsrc_le= n); > > - if (!hcd->regs) { > > - dev_err(&pdev->dev, "Failed to remap I/O memory\n"); > > - err =3D -ENOMEM; > > + hcd->regs =3D devm_ioremap_resource(&pdev->dev, res); >=20 > Here, we replaced devm_ioremap() call with devm_ioremap_resource(), > which internally requests the memory region I guess this could lead to problems if drivers haven't been written to cleanly split the register ranges that they access, since now two overlapping regions may be requested and cause the drivers to fail. > and then does a "devm_ioremap()" or "devm_ioremap_nocache()" based on > the check for IORESOURCE_CACHEABLE flag. >=20 > But this flag is not set for the resource of this device. > So should we be explicitly setting the flag in driver ? I don't think it makes much sense to map these registers cached anyway. Drivers will likely expect writes to this region to take effect without needing any kind of flushing. Thierry --7ZAtKRhVyVSsbBD2 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIcBAEBAgAGBQJTjxtiAAoJEN0jrNd/PrOhiTYP/2NPPViprewJ60qZhUc+hJ7G hMv0Qa08HrSeNLnHN/jOqIwdgDMFSy/8Um2yCyqH5Wpy0+ohJL2V0PuBuXA/ZIbO ZQ6Q3CChqGxqc939kaVjoeLYlNJCPaz2lkxqGHpuSLDY9ojIbbHgfPbEVFeQj6Z4 6+VkGh06/+Ato8Rpp5xmzr77x9qujLzGPe6e8zS7cr272TwBXBgBGo/jUBHt4aE1 EKo4TQtVfkBXIeSqvSKBXQSxVq3ADWOS5EOl7o0MTfoxd/2DKt3Ktd8SFisvBCWQ aGu6QjHIaEMiAjmAwIYSTZW9Djw1x62xgdRA/ZFQufLJK2anwxgKv+jEz0Fz1XPu LSJCGiCWzma9IywPEc5abTRSsfIYI6iQJxwq7Fg4Z2ssLII6aPljyozbUm81YjxS ViB8OtzJnUjqcpca2UmDfvuG3Ty3LgyH+mopNP28daMcEeY4LczBX/Pk3uftS2Nm +s+Whk9Ssv1WNlYz4nq737PuwnZ8leSf8hhfPDqWh9Zw8mZ/F8Cv/jqWEF7vK7ar lckvyWfGH/9CYqZu/WYgzid70hO4T32SnS+sJiqx/6/oGqI1bVEc+JVcNherwL88 azmSggvCzovSD9B9Tlp4Bu2Lj7tSfsmHPIOvf5CVsKUHWWJYT6egfnm/vin2Y2L3 +3awh4NG713uFf5l4gfm =1dt2 -----END PGP SIGNATURE----- --7ZAtKRhVyVSsbBD2-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/