From: Finn Thain <fthain@telegraphics.com.au> To: Geert Uytterhoeven <geert@linux-m68k.org> Cc: "David S. Miller" <davem@davemloft.net>, linux-m68k <linux-m68k@vger.kernel.org>, netdev <netdev@vger.kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Christoph Hellwig <hch@lst.de> Subject: Re: [PATCH net] macmace: Set platform device coherent_dma_mask Date: Thu, 10 May 2018 11:25:35 +1000 (AEST) [thread overview] Message-ID: <alpine.LNX.2.21.1805091805130.72@nippy.intranet> (raw) In-Reply-To: <CAMuHMdU1XBqt7hwEW6JTas64ZNGCGCMr5HMZwuLo0O-ZBCOWyA@mail.gmail.com> On Thu, 3 May 2018, Geert Uytterhoeven wrote: > > Perhaps you can add a new helper > (platform_device_register_simple_dma()?) that takes the DMA mask, too? Would there be enough potential callers in future to justify that API? It seems that there haven't been many in the past. I found four users of platform_device_register_simple() which might benefit. Mostly these call dma_set_coherent_mask() in the platform driver probe routine. drivers/gpu/drm/etnaviv/etnaviv_drv.c drivers/gpu/drm/exynos/exynos_drm_drv.c drivers/gpu/drm/omapdrm/omap_drv.c drivers/parport/parport_pc.c (Am I missing any others?) To actually hoist the dma mask setup out of existing platform drivers would have implications for every device that matches with those drivers. That's a bit risky since I can't test those devices -- that's assuming I could identify them all; sometimes platform device matching is not well defined at build time (see loongson_sysconf.ecname). So far, it looks like macmace and macsonic would be the only callers of this new API call. What's worse, if you do pass a dma_mask in struct platform_device_info, you end up with this problem in platform_device_register_full(): if (pdevinfo->dma_mask) { /* * This memory isn't freed when the device is put, * I don't have a nice idea for that though. Conceptually * dma_mask in struct device should not be a pointer. * See http://thread.gmane.org/gmane.linux.kernel.pci/9081 */ pdev->dev.dma_mask = kmalloc(sizeof(*pdev->dev.dma_mask), GFP_KERNEL); Most of the platform drivers that call dma_coerce_mask_and_coherent() are using pdev->of_match_table, not platform_device_register_simple(). Many of them have a comment like this: /* * Right now device-tree probed devices don't get dma_mask set. * Since shared usb code relies on it, set it here for now. * Once we have dma capability bindings this can go away. */ > With people setting the mask to kill the WARNING splat, this may become > more common. Since the commit which introduced the WARNING, only commits f61e64310b75 ("m68k: set dma and coherent masks for platform FEC ethernets") and 7bcfab202ca7 ("powerpc/macio: set a proper dma_coherent_mask") seem to be aimed at squelching that WARNING. (Am I missing any others?) So far, this is not looking like a common problem, and I'm having trouble finding some way to improve on my original patches. --
WARNING: multiple messages have this Message-ID (diff)
From: Finn Thain <fthain@telegraphics.com.au> To: Geert Uytterhoeven <geert@linux-m68k.org> Cc: "David S. Miller" <davem@davemloft.net>, linux-m68k <linux-m68k@lists.linux-m68k.org>, netdev <netdev@vger.kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Christoph Hellwig <hch@lst.de> Subject: Re: [PATCH net] macmace: Set platform device coherent_dma_mask Date: Thu, 10 May 2018 11:25:35 +1000 (AEST) [thread overview] Message-ID: <alpine.LNX.2.21.1805091805130.72@nippy.intranet> (raw) In-Reply-To: <CAMuHMdU1XBqt7hwEW6JTas64ZNGCGCMr5HMZwuLo0O-ZBCOWyA@mail.gmail.com> On Thu, 3 May 2018, Geert Uytterhoeven wrote: > > Perhaps you can add a new helper > (platform_device_register_simple_dma()?) that takes the DMA mask, too? Would there be enough potential callers in future to justify that API? It seems that there haven't been many in the past. I found four users of platform_device_register_simple() which might benefit. Mostly these call dma_set_coherent_mask() in the platform driver probe routine. drivers/gpu/drm/etnaviv/etnaviv_drv.c drivers/gpu/drm/exynos/exynos_drm_drv.c drivers/gpu/drm/omapdrm/omap_drv.c drivers/parport/parport_pc.c (Am I missing any others?) To actually hoist the dma mask setup out of existing platform drivers would have implications for every device that matches with those drivers. That's a bit risky since I can't test those devices -- that's assuming I could identify them all; sometimes platform device matching is not well defined at build time (see loongson_sysconf.ecname). So far, it looks like macmace and macsonic would be the only callers of this new API call. What's worse, if you do pass a dma_mask in struct platform_device_info, you end up with this problem in platform_device_register_full(): if (pdevinfo->dma_mask) { /* * This memory isn't freed when the device is put, * I don't have a nice idea for that though. Conceptually * dma_mask in struct device should not be a pointer. * See http://thread.gmane.org/gmane.linux.kernel.pci/9081 */ pdev->dev.dma_mask = kmalloc(sizeof(*pdev->dev.dma_mask), GFP_KERNEL); Most of the platform drivers that call dma_coerce_mask_and_coherent() are using pdev->of_match_table, not platform_device_register_simple(). Many of them have a comment like this: /* * Right now device-tree probed devices don't get dma_mask set. * Since shared usb code relies on it, set it here for now. * Once we have dma capability bindings this can go away. */ > With people setting the mask to kill the WARNING splat, this may become > more common. Since the commit which introduced the WARNING, only commits f61e64310b75 ("m68k: set dma and coherent masks for platform FEC ethernets") and 7bcfab202ca7 ("powerpc/macio: set a proper dma_coherent_mask") seem to be aimed at squelching that WARNING. (Am I missing any others?) So far, this is not looking like a common problem, and I'm having trouble finding some way to improve on my original patches. --
next prev parent reply other threads:[~2018-05-10 1:25 UTC|newest] Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <S1751632AbeECEYA/20180503042400Z+254@vger.kernel.org> 2018-05-03 7:25 ` [PATCH net] macmace: Set platform device coherent_dma_mask Geert Uytterhoeven 2018-05-03 7:25 ` Geert Uytterhoeven 2018-05-03 8:38 ` Finn Thain 2018-05-03 8:38 ` Finn Thain 2018-05-03 8:46 ` Geert Uytterhoeven 2018-05-03 8:46 ` Geert Uytterhoeven 2018-05-03 8:51 ` Christoph Hellwig 2018-05-03 8:51 ` Christoph Hellwig 2018-05-03 20:24 ` Michael Schmitz 2018-05-03 20:24 ` Michael Schmitz 2018-05-04 7:24 ` Geert Uytterhoeven 2018-05-04 7:24 ` Geert Uytterhoeven 2018-05-04 8:16 ` Michael Schmitz 2018-05-04 8:16 ` Michael Schmitz 2018-05-10 1:25 ` Finn Thain 2018-05-10 1:25 ` Finn Thain 2018-05-10 1:25 ` Finn Thain [this message] 2018-05-10 1:25 ` Finn Thain 2018-05-10 20:27 ` Michael Schmitz 2018-05-10 20:27 ` Michael Schmitz 2018-05-10 23:55 ` Finn Thain 2018-05-10 23:55 ` Finn Thain 2018-05-11 2:11 ` Michael Schmitz 2018-05-11 2:11 ` Michael Schmitz 2018-05-11 3:28 ` Finn Thain 2018-05-11 3:28 ` Finn Thain 2018-05-11 4:18 ` Michael Schmitz 2018-05-11 4:18 ` Michael Schmitz 2018-05-11 5:28 ` Finn Thain 2018-05-11 5:28 ` Finn Thain 2018-05-11 9:30 ` Michael Schmitz 2018-05-11 9:30 ` Michael Schmitz 2018-05-11 10:06 ` Finn Thain 2018-05-11 10:06 ` Finn Thain 2018-05-11 22:02 ` Michael Schmitz 2018-05-11 22:02 ` Michael Schmitz 2018-05-03 4:23 Finn Thain -- strict thread matches above, loose matches on Subject: below -- 2018-05-03 4:23 Finn Thain 2018-05-03 4:23 Finn Thain 2018-05-03 4:23 Finn Thain 2018-05-03 4:23 Finn Thain
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