From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH v2 2/9] mailbox: Add NVIDIA Tegra XUSB mailbox driver Date: Tue, 26 Aug 2014 12:20:13 +0200 Message-ID: <20140826102011.GA31124@ulmo> References: <1408381705-3623-1-git-send-email-abrestic@chromium.org> <6589717.GOLq1GlTCJ@wuerfel> <20140826090810.GH17263@ulmo> <5184912.mY2hCPH20k@wuerfel> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="y0ulUmNC+osPPQO6" Return-path: Content-Disposition: inline In-Reply-To: <5184912.mY2hCPH20k@wuerfel> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Arnd Bergmann Cc: Stephen Warren , Andrew Bresticker , linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Russell King , Jassi Brar , Linus Walleij , Greg Kroah-Hartman , Mathias Nyman , Grant Likely , Alan Stern , Kishon Vijay Abraham I , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Jonas Bonn , David Howells , Koichi Yasutake List-Id: linux-tegra@vger.kernel.org --y0ulUmNC+osPPQO6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Aug 26, 2014 at 11:54:43AM +0200, Arnd Bergmann wrote: > On Tuesday 26 August 2014 11:08:11 Thierry Reding wrote: > > On Tue, Aug 26, 2014 at 10:09:25AM +0200, Arnd Bergmann wrote: > > > On Tuesday 26 August 2014 09:50:25 Thierry Reding wrote: > > > > On Tue, Aug 26, 2014 at 09:43:50AM +0200, Arnd Bergmann wrote: > > > > > On Tuesday 26 August 2014 08:57:31 Thierry Reding wrote: > > > > > > On Mon, Aug 25, 2014 at 01:01:52PM -0600, Stephen Warren wrote: > > > > > > > On 08/18/2014 11:08 AM, Andrew Bresticker wrote: > > > > > > [...] > > > > > > > >+static int tegra_xusb_mbox_probe(struct platform_device *pd= ev) > > > > > > >=20 > > > > > > > >+ res =3D platform_get_resource(pdev, IORESOURCE_MEM, 0); > > > > > > > >+ if (!res) > > > > > > > >+ return -ENODEV; > > > > > > >=20 > > > > > > > Should devm_request_mem_region() be called here to claim the = region? > > > > > > >=20 > > > > > > > >+ mbox->regs =3D devm_ioremap_nocache(&pdev->dev, res->st= art, > > > > > > > >+ resource_size(res)); > > > > > > > >+ if (!mbox->regs) > > > > > > > >+ return -ENOMEM; > > > > > > >=20 > > > > > > > Is _nocache required? I don't see other drivers using it. I a= ssume there's > > > > > > > nothing special about the mbox registers. > > > > > >=20 > > > > > > Most drivers should be using devm_ioremap_resource() which will= use the > > > > > > _nocache variant of devm_ioremap() when appropriate. Usually th= e region > > > > > > will not be marked cacheable (IORESOURCE_CACHEABLE) and therefo= re be > > > > > > remapped uncached. > > > > > >=20 > > > > >=20 > > > > > Note that ioremap() and ioremap_nocache() are the same. We really= shouldn't > > > > > ever call ioremap_nocache(). > > > >=20 > > > > Perhaps we should remove ioremap_nocache() in that case. Or ioremap= (), > > > > really, and keep only those variants that do what they claim to do. > > >=20 > > > That would be good, but there are many instances of either one: > > >=20 > > > arnd@wuerfel:/git/arm-soc$ git grep -w ioremap | wc > > > 2156 13402 183732 > > > arnd@wuerfel:/git/arm-soc$ git grep -w ioremap_nocache | wc > > > 485 2529 42955 > >=20 > > Ugh... nothing that I currently have time for. Perhaps this is a good > > one for the Janitors? I'm not sure if the kernelnewbies.org TODO list is > > still frequented since many pages seem to be very old. Is there some > > other place where I could add this? >=20 > I'm not sure if it's really worth it. One thing we might do is just > remove all definitions of ioremap_nocache and add a wrapper to > include/linux/io.h, to make it more obvious what is going on. Yes, I suppose that would work too. I still think there's an advantage in being explicit and avoid aliases like this. Perhaps a __deprecated annotation would help with that? > > > > > devm_ioremap_resource() and pci_iomap() checking for IORESOURCE_C= ACHEABLE is > > > > > rather silly, since it doesn't call ioremap_cache() in that case. > > > >=20 > > > > Then that should be fixed. > > >=20 > > > Yes. I'd suggest we just ignore that flag and always call ioremap her= e. > > >=20 > > > When I checked this before, IORESOURCE_CACHEABLE only ever gets set f= or > > > PCI ROM BARs, which we don't map into the kernel. > >=20 > > There's still a few users of ioremap_cache() around and they are > > potential candidates for a conversion to devm_ioremap_resource(), so I > > think it'd still make sense to keep the check. >=20 > Possibly. Note that these are all in architecture-specific code, as > evidenced by the fact that we have multiple names for this function: >=20 > ioremap_cache: arm, arm64, x86, ia64, sh > ioremap_cached: metag, unicore32 > ioremap_cachable: mips >=20 > All other architectures have none of the above. >=20 > An alternative approach would be to kill off IORESOURCE_CACHEABLE > and introduce a devm_ioremap_resource_cache() helper when the first > driver wants it. Looking briefly at the involved headers and structure there seems to be quite a bit of potential for cleanup. Thierry --y0ulUmNC+osPPQO6 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBAgAGBQJT/F9bAAoJEN0jrNd/PrOhgSIQAMKJkrzmA1H5ar+Iu79XUooi 9ps9CLjBlUwUsBqSeQwwAwO1kr+DkL9FDF0VDhqRwEBsc69D7AapHKQVeAour6K/ KNApylCSNJIBRfogzF1jGx22eNgksdWQoJnjqvZ6W0xnUFqZMmXdJnIkqZrFLZAz VrJRhv25XGj48THGHLXSRCPiPYDlN1MBOeynZE3Id9JfotbNSOm5keNYxsop1IHo rnFObgQO0RwUrCTkcsvlmllY6KNefKBgWiJrAtjtMn3pkhLlqm+/aiHliFLmaeDx n82cWEJ2lTTFxcSRuqitgkns/3djpupHG7Y/4RMpoY1wQSuD61ZFxUad0PFyxrBX GdcxEMZxRu2W2kLi7Dw1n7sShNQ4YmgT/77YDbzZZWNRrMGG7r4puu+ZDAt3xtyI zfFqBCMU3dUbRG6fmaaNbcHtuNwOveglLc+2ygUo4Q5T0ZHBhqSE2yTjQhl1T8Uc QKvGSony27RpF5qIsu1T77su+rR3FC3oJcm++I06riWPgP3aqvLJx+9ow/MqjDhP cs+gQv63euUmTXOn/E2AvPMAliwzJVty/XIBCsS+JwgvZJTidBvSxSSXemMVOSKT GuND45c/1ouiu/IB7ajf+ZQzVgsubvl6N7VicRQ/xETjJR+MoSxQIOTSXGDpYcKu 1vXZsvDJFevi+M4p1LJL =3EXS -----END PGP SIGNATURE----- --y0ulUmNC+osPPQO6-- -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934545AbaHZKUX (ORCPT ); Tue, 26 Aug 2014 06:20:23 -0400 Received: from mail-we0-f174.google.com ([74.125.82.174]:58471 "EHLO mail-we0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932472AbaHZKUU (ORCPT ); Tue, 26 Aug 2014 06:20:20 -0400 Date: Tue, 26 Aug 2014 12:20:13 +0200 From: Thierry Reding To: Arnd Bergmann Cc: Stephen Warren , Andrew Bresticker , linux-tegra@vger.kernel.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Russell King , Jassi Brar , Linus Walleij , Greg Kroah-Hartman , Mathias Nyman , Grant Likely , Alan Stern , Kishon Vijay Abraham I , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-usb@vger.kernel.org, Jonas Bonn , David Howells , Koichi Yasutake Subject: Re: [PATCH v2 2/9] mailbox: Add NVIDIA Tegra XUSB mailbox driver Message-ID: <20140826102011.GA31124@ulmo> References: <1408381705-3623-1-git-send-email-abrestic@chromium.org> <6589717.GOLq1GlTCJ@wuerfel> <20140826090810.GH17263@ulmo> <5184912.mY2hCPH20k@wuerfel> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="y0ulUmNC+osPPQO6" Content-Disposition: inline In-Reply-To: <5184912.mY2hCPH20k@wuerfel> 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 --y0ulUmNC+osPPQO6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Aug 26, 2014 at 11:54:43AM +0200, Arnd Bergmann wrote: > On Tuesday 26 August 2014 11:08:11 Thierry Reding wrote: > > On Tue, Aug 26, 2014 at 10:09:25AM +0200, Arnd Bergmann wrote: > > > On Tuesday 26 August 2014 09:50:25 Thierry Reding wrote: > > > > On Tue, Aug 26, 2014 at 09:43:50AM +0200, Arnd Bergmann wrote: > > > > > On Tuesday 26 August 2014 08:57:31 Thierry Reding wrote: > > > > > > On Mon, Aug 25, 2014 at 01:01:52PM -0600, Stephen Warren wrote: > > > > > > > On 08/18/2014 11:08 AM, Andrew Bresticker wrote: > > > > > > [...] > > > > > > > >+static int tegra_xusb_mbox_probe(struct platform_device *pd= ev) > > > > > > >=20 > > > > > > > >+ res =3D platform_get_resource(pdev, IORESOURCE_MEM, 0); > > > > > > > >+ if (!res) > > > > > > > >+ return -ENODEV; > > > > > > >=20 > > > > > > > Should devm_request_mem_region() be called here to claim the = region? > > > > > > >=20 > > > > > > > >+ mbox->regs =3D devm_ioremap_nocache(&pdev->dev, res->st= art, > > > > > > > >+ resource_size(res)); > > > > > > > >+ if (!mbox->regs) > > > > > > > >+ return -ENOMEM; > > > > > > >=20 > > > > > > > Is _nocache required? I don't see other drivers using it. I a= ssume there's > > > > > > > nothing special about the mbox registers. > > > > > >=20 > > > > > > Most drivers should be using devm_ioremap_resource() which will= use the > > > > > > _nocache variant of devm_ioremap() when appropriate. Usually th= e region > > > > > > will not be marked cacheable (IORESOURCE_CACHEABLE) and therefo= re be > > > > > > remapped uncached. > > > > > >=20 > > > > >=20 > > > > > Note that ioremap() and ioremap_nocache() are the same. We really= shouldn't > > > > > ever call ioremap_nocache(). > > > >=20 > > > > Perhaps we should remove ioremap_nocache() in that case. Or ioremap= (), > > > > really, and keep only those variants that do what they claim to do. > > >=20 > > > That would be good, but there are many instances of either one: > > >=20 > > > arnd@wuerfel:/git/arm-soc$ git grep -w ioremap | wc > > > 2156 13402 183732 > > > arnd@wuerfel:/git/arm-soc$ git grep -w ioremap_nocache | wc > > > 485 2529 42955 > >=20 > > Ugh... nothing that I currently have time for. Perhaps this is a good > > one for the Janitors? I'm not sure if the kernelnewbies.org TODO list is > > still frequented since many pages seem to be very old. Is there some > > other place where I could add this? >=20 > I'm not sure if it's really worth it. One thing we might do is just > remove all definitions of ioremap_nocache and add a wrapper to > include/linux/io.h, to make it more obvious what is going on. Yes, I suppose that would work too. I still think there's an advantage in being explicit and avoid aliases like this. Perhaps a __deprecated annotation would help with that? > > > > > devm_ioremap_resource() and pci_iomap() checking for IORESOURCE_C= ACHEABLE is > > > > > rather silly, since it doesn't call ioremap_cache() in that case. > > > >=20 > > > > Then that should be fixed. > > >=20 > > > Yes. I'd suggest we just ignore that flag and always call ioremap her= e. > > >=20 > > > When I checked this before, IORESOURCE_CACHEABLE only ever gets set f= or > > > PCI ROM BARs, which we don't map into the kernel. > >=20 > > There's still a few users of ioremap_cache() around and they are > > potential candidates for a conversion to devm_ioremap_resource(), so I > > think it'd still make sense to keep the check. >=20 > Possibly. Note that these are all in architecture-specific code, as > evidenced by the fact that we have multiple names for this function: >=20 > ioremap_cache: arm, arm64, x86, ia64, sh > ioremap_cached: metag, unicore32 > ioremap_cachable: mips >=20 > All other architectures have none of the above. >=20 > An alternative approach would be to kill off IORESOURCE_CACHEABLE > and introduce a devm_ioremap_resource_cache() helper when the first > driver wants it. Looking briefly at the involved headers and structure there seems to be quite a bit of potential for cleanup. Thierry --y0ulUmNC+osPPQO6 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBAgAGBQJT/F9bAAoJEN0jrNd/PrOhgSIQAMKJkrzmA1H5ar+Iu79XUooi 9ps9CLjBlUwUsBqSeQwwAwO1kr+DkL9FDF0VDhqRwEBsc69D7AapHKQVeAour6K/ KNApylCSNJIBRfogzF1jGx22eNgksdWQoJnjqvZ6W0xnUFqZMmXdJnIkqZrFLZAz VrJRhv25XGj48THGHLXSRCPiPYDlN1MBOeynZE3Id9JfotbNSOm5keNYxsop1IHo rnFObgQO0RwUrCTkcsvlmllY6KNefKBgWiJrAtjtMn3pkhLlqm+/aiHliFLmaeDx n82cWEJ2lTTFxcSRuqitgkns/3djpupHG7Y/4RMpoY1wQSuD61ZFxUad0PFyxrBX GdcxEMZxRu2W2kLi7Dw1n7sShNQ4YmgT/77YDbzZZWNRrMGG7r4puu+ZDAt3xtyI zfFqBCMU3dUbRG6fmaaNbcHtuNwOveglLc+2ygUo4Q5T0ZHBhqSE2yTjQhl1T8Uc QKvGSony27RpF5qIsu1T77su+rR3FC3oJcm++I06riWPgP3aqvLJx+9ow/MqjDhP cs+gQv63euUmTXOn/E2AvPMAliwzJVty/XIBCsS+JwgvZJTidBvSxSSXemMVOSKT GuND45c/1ouiu/IB7ajf+ZQzVgsubvl6N7VicRQ/xETjJR+MoSxQIOTSXGDpYcKu 1vXZsvDJFevi+M4p1LJL =3EXS -----END PGP SIGNATURE----- --y0ulUmNC+osPPQO6-- From mboxrd@z Thu Jan 1 00:00:00 1970 From: thierry.reding@gmail.com (Thierry Reding) Date: Tue, 26 Aug 2014 12:20:13 +0200 Subject: [PATCH v2 2/9] mailbox: Add NVIDIA Tegra XUSB mailbox driver In-Reply-To: <5184912.mY2hCPH20k@wuerfel> References: <1408381705-3623-1-git-send-email-abrestic@chromium.org> <6589717.GOLq1GlTCJ@wuerfel> <20140826090810.GH17263@ulmo> <5184912.mY2hCPH20k@wuerfel> Message-ID: <20140826102011.GA31124@ulmo> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Aug 26, 2014 at 11:54:43AM +0200, Arnd Bergmann wrote: > On Tuesday 26 August 2014 11:08:11 Thierry Reding wrote: > > On Tue, Aug 26, 2014 at 10:09:25AM +0200, Arnd Bergmann wrote: > > > On Tuesday 26 August 2014 09:50:25 Thierry Reding wrote: > > > > On Tue, Aug 26, 2014 at 09:43:50AM +0200, Arnd Bergmann wrote: > > > > > On Tuesday 26 August 2014 08:57:31 Thierry Reding wrote: > > > > > > On Mon, Aug 25, 2014 at 01:01:52PM -0600, Stephen Warren wrote: > > > > > > > On 08/18/2014 11:08 AM, Andrew Bresticker wrote: > > > > > > [...] > > > > > > > >+static int tegra_xusb_mbox_probe(struct platform_device *pdev) > > > > > > > > > > > > > > >+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > > > > > > > >+ if (!res) > > > > > > > >+ return -ENODEV; > > > > > > > > > > > > > > Should devm_request_mem_region() be called here to claim the region? > > > > > > > > > > > > > > >+ mbox->regs = devm_ioremap_nocache(&pdev->dev, res->start, > > > > > > > >+ resource_size(res)); > > > > > > > >+ if (!mbox->regs) > > > > > > > >+ return -ENOMEM; > > > > > > > > > > > > > > Is _nocache required? I don't see other drivers using it. I assume there's > > > > > > > nothing special about the mbox registers. > > > > > > > > > > > > Most drivers should be using devm_ioremap_resource() which will use the > > > > > > _nocache variant of devm_ioremap() when appropriate. Usually the region > > > > > > will not be marked cacheable (IORESOURCE_CACHEABLE) and therefore be > > > > > > remapped uncached. > > > > > > > > > > > > > > > > Note that ioremap() and ioremap_nocache() are the same. We really shouldn't > > > > > ever call ioremap_nocache(). > > > > > > > > Perhaps we should remove ioremap_nocache() in that case. Or ioremap(), > > > > really, and keep only those variants that do what they claim to do. > > > > > > That would be good, but there are many instances of either one: > > > > > > arnd at wuerfel:/git/arm-soc$ git grep -w ioremap | wc > > > 2156 13402 183732 > > > arnd at wuerfel:/git/arm-soc$ git grep -w ioremap_nocache | wc > > > 485 2529 42955 > > > > Ugh... nothing that I currently have time for. Perhaps this is a good > > one for the Janitors? I'm not sure if the kernelnewbies.org TODO list is > > still frequented since many pages seem to be very old. Is there some > > other place where I could add this? > > I'm not sure if it's really worth it. One thing we might do is just > remove all definitions of ioremap_nocache and add a wrapper to > include/linux/io.h, to make it more obvious what is going on. Yes, I suppose that would work too. I still think there's an advantage in being explicit and avoid aliases like this. Perhaps a __deprecated annotation would help with that? > > > > > devm_ioremap_resource() and pci_iomap() checking for IORESOURCE_CACHEABLE is > > > > > rather silly, since it doesn't call ioremap_cache() in that case. > > > > > > > > Then that should be fixed. > > > > > > Yes. I'd suggest we just ignore that flag and always call ioremap here. > > > > > > When I checked this before, IORESOURCE_CACHEABLE only ever gets set for > > > PCI ROM BARs, which we don't map into the kernel. > > > > There's still a few users of ioremap_cache() around and they are > > potential candidates for a conversion to devm_ioremap_resource(), so I > > think it'd still make sense to keep the check. > > Possibly. Note that these are all in architecture-specific code, as > evidenced by the fact that we have multiple names for this function: > > ioremap_cache: arm, arm64, x86, ia64, sh > ioremap_cached: metag, unicore32 > ioremap_cachable: mips > > All other architectures have none of the above. > > An alternative approach would be to kill off IORESOURCE_CACHEABLE > and introduce a devm_ioremap_resource_cache() helper when the first > driver wants it. Looking briefly at the involved headers and structure there seems to be quite a bit of potential for cleanup. Thierry -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 819 bytes Desc: not available URL: