From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: Re: [PATCH 6/6] driver core: initialize a default DMA mask for platform device Date: Thu, 15 Aug 2019 16:05:16 +0200 Message-ID: <20190815140516.GB7174@kroah.com> References: <20190811080520.21712-1-hch@lst.de> <20190811080520.21712-7-hch@lst.de> <20190815130325.GB17065@kroah.com> <20190815133812.GF12036@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190815133812.GF12036@lst.de> Sender: linux-kernel-owner@vger.kernel.org To: Christoph Hellwig Cc: Maxime Chevallier , Gavin Li , Laurentiu Tudor , Minas Harutyunyan , Alan Stern , Geoff Levand , Michal Simek , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , Olav Kongas , Tony Prisk , Mathias Nyman , Bin Liu , linux-arm-kernel@lists.infradead.org, linux-usb@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, iommu@lists.linux-foundation.org, linux-arch@vger.kerne List-Id: linux-arch.vger.kernel.org On Thu, Aug 15, 2019 at 03:38:12PM +0200, Christoph Hellwig wrote: > On Thu, Aug 15, 2019 at 03:03:25PM +0200, Greg Kroah-Hartman wrote: > > > --- a/include/linux/platform_device.h > > > +++ b/include/linux/platform_device.h > > > @@ -24,6 +24,7 @@ struct platform_device { > > > int id; > > > bool id_auto; > > > struct device dev; > > > + u64 dma_mask; > > > > Why is the dma_mask in 'struct device' which is part of this structure, > > not sufficient here? Shouldn't the "platform" be setting that up > > correctly already in the "archdata" type callback? > > Becaus the dma_mask in struct device is a pointer that needs to point > to something, and this is the best space we can allocate for 'something'. > m68k and powerpc currently do something roughly equivalent at the moment, > while everyone else just has horrible, horrible hacks. As mentioned in > the changelog the intent of this patch is that we treat platform devices > like any other bus, where the bus allocates the space for the dma_mask. > The long term plan is to eventually kill that weird pointer indirection > that doesn't help anyone, but for that we need to sort out the basics > first. Ah, missed that, sorry. Ok, no objection from me. Might as well respin this series and I can queue it up after 5.3-rc5 is out (which will have your first 2 patches in it.) thanks, greg k-h From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:48612 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732211AbfHOOFT (ORCPT ); Thu, 15 Aug 2019 10:05:19 -0400 Date: Thu, 15 Aug 2019 16:05:16 +0200 From: Greg Kroah-Hartman Subject: Re: [PATCH 6/6] driver core: initialize a default DMA mask for platform device Message-ID: <20190815140516.GB7174@kroah.com> References: <20190811080520.21712-1-hch@lst.de> <20190811080520.21712-7-hch@lst.de> <20190815130325.GB17065@kroah.com> <20190815133812.GF12036@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190815133812.GF12036@lst.de> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Christoph Hellwig Cc: Maxime Chevallier , Gavin Li , Laurentiu Tudor , Minas Harutyunyan , Alan Stern , Geoff Levand , Michal Simek , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , Olav Kongas , Tony Prisk , Mathias Nyman , Bin Liu , linux-arm-kernel@lists.infradead.org, linux-usb@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, iommu@lists.linux-foundation.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <20190815140516.eT2I-hqjRo5H3rmrHRGpkAJzKs59Dg5tfvYumzVlRvA@z> On Thu, Aug 15, 2019 at 03:38:12PM +0200, Christoph Hellwig wrote: > On Thu, Aug 15, 2019 at 03:03:25PM +0200, Greg Kroah-Hartman wrote: > > > --- a/include/linux/platform_device.h > > > +++ b/include/linux/platform_device.h > > > @@ -24,6 +24,7 @@ struct platform_device { > > > int id; > > > bool id_auto; > > > struct device dev; > > > + u64 dma_mask; > > > > Why is the dma_mask in 'struct device' which is part of this structure, > > not sufficient here? Shouldn't the "platform" be setting that up > > correctly already in the "archdata" type callback? > > Becaus the dma_mask in struct device is a pointer that needs to point > to something, and this is the best space we can allocate for 'something'. > m68k and powerpc currently do something roughly equivalent at the moment, > while everyone else just has horrible, horrible hacks. As mentioned in > the changelog the intent of this patch is that we treat platform devices > like any other bus, where the bus allocates the space for the dma_mask. > The long term plan is to eventually kill that weird pointer indirection > that doesn't help anyone, but for that we need to sort out the basics > first. Ah, missed that, sorry. Ok, no objection from me. Might as well respin this series and I can queue it up after 5.3-rc5 is out (which will have your first 2 patches in it.) thanks, greg k-h