From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexandre Courbot Subject: Re: [PATCH 1/2] drm/tegra: Set DMA ops Date: Wed, 24 Feb 2016 17:30:54 +0900 Message-ID: <56CD6A3E.4090800@nvidia.com> References: <1456208754-12362-1-git-send-email-acourbot@nvidia.com> <20160223152815.GD27656@ulmo> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160223152815.GD27656@ulmo> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thierry Reding Cc: =?UTF-8?Q?Terje_Bergstr=c3=b6m?= , Stephen Warren , dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, gnurou-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org List-Id: linux-tegra@vger.kernel.org On 02/24/2016 12:28 AM, Thierry Reding wrote: > * PGP Signed by an unknown key > > On Tue, Feb 23, 2016 at 03:25:53PM +0900, Alexandre Courbot wrote: >> The current settings leaves the DRM device's dma_ops field NULL, which >> makes it use the dummy DMA ops on arm64 and return an error whenever we >> try to import a buffer. Call of_dma_configure() with a NULL node (since >> the device is not spawn from the device tree) so that >> arch_setup_dma_ops() is called and sets the default ioswtlb DMA ops. >> >> Signed-off-by: Alexandre Courbot >> --- >> drivers/gpu/drm/tegra/drm.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c >> index d347188bf8f4..bc0555adecaf 100644 >> --- a/drivers/gpu/drm/tegra/drm.c >> +++ b/drivers/gpu/drm/tegra/drm.c >> @@ -9,6 +9,7 @@ >> >> #include >> #include >> +#include >> >> #include >> #include >> @@ -990,6 +991,7 @@ static int host1x_drm_probe(struct host1x_device *dev) >> return -ENOMEM; >> >> dev_set_drvdata(&dev->dev, drm); >> + of_dma_configure(drm->dev, NULL); > > Looking at the various pieces, I think this really belongs in > host1x_device_add() (see drivers/gpu/host1x/bus.c) where it can replace > the open-coded setting of DMA and coherent DMA masks. Also why can't we > pass the correct device tree node here? The DRM device is a virtual > device that hangs off the host1x device, so I think it could use the > same device tree node as the host1x device. > > Something like the below (untested). You're right, that looks like a much better place to do this. of_dma_configure() is called at the bus level (platform and PCI), so it makes sense to do it from host1x too.