On Mon, 22 Sep 2014 16:43:31 +0200
Arnd Bergmann <arnd@xxxxxxxx> wrote:
> On Monday 22 September 2014 18:48:54 Mark yao wrote:
> > diff --git a/drivers/gpu/drm/rockchip/Kconfig b/drivers/gpu/drm/rockchip/Kconfig
> > new file mode 100644
> > index 0000000..7146c80
> > --- /dev/null
> > +++ b/drivers/gpu/drm/rockchip/Kconfig
> > @@ -0,0 +1,19 @@
> > +config DRM_ROCKCHIP
> > + tristate "DRM Support for Rockchip"
> > + depends on DRM && ROCKCHIP_IOMMU
> > + select ARM_DMA_USE_IOMMU
> > + select IOMMU_API
> > + select DRM_KMS_HELPER
> > + select DRM_KMS_FB_HELPER
> > + select DRM_PANEL
> > + select FB_CFB_FILLRECT
> > + select FB_CFB_COPYAREA
> > + select FB_CFB_IMAGEBLIT
> > + select VT_HW_CONSOLE_BINDING if FRAMEBUFFER_CONSOLE
> > + select VIDEOMODE_HELPERS
>
> Be careful with 'select', at least some of these should be 'depends on'.
> In particular IOMMU_API and ARM_DMA_USE_IOMMU, but possibly others
> as well. Just check how the symbols are used normally, if you get this
> wrong, we can end up with incorrect dependencies or loops.
>
> > diff --git a/drivers/gpu/drm/rockchip/Makefile b/drivers/gpu/drm/rockchip/Makefile
> > new file mode 100644
> > index 0000000..6e6d468
> > --- /dev/null
> > +++ b/drivers/gpu/drm/rockchip/Makefile
> > @@ -0,0 +1,10 @@
> > +#
> > +# Makefile for the drm device driver. This driver provides support for the
> > +# Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
> > +
> > +ccflags-y := -Iinclude/drm -Idrivers/gpu/drm/rockchip
>
> The second one should not be required.
>
> > +static int rockchip_drm_load(struct drm_device *drm_dev, unsigned long flags)
> > +{
> > + struct rockchip_drm_private *private;
> > + struct dma_iommu_mapping *mapping;
> > + struct device *dev = drm_dev->dev;
> > + int ret;
> > +
> > + private = devm_kzalloc(drm_dev->dev, sizeof(*private), GFP_KERNEL);
> > + if (!private)
> > + return -ENOMEM;
> > +
> > + dev_set_drvdata(drm_dev->dev, dev);
> > + drm_dev->dev_private = private;
> > +
> > + drm_mode_config_init(drm_dev);
> > +
> > + rockchip_drm_mode_config_init(drm_dev);
> > +
> > + dev->dma_parms = devm_kzalloc(dev, sizeof(*dev->dma_parms),
> > + GFP_KERNEL);
> > + if (!dev->dma_parms) {
> > + ret = -ENOMEM;
> > + goto err_config_cleanup;
> > + }
> > +
> > + /* TODO(djkurtz): fetch the mapping start/size from somewhere */
> > + mapping = arm_iommu_create_mapping(&platform_bus_type, 0x10000000,
> > + SZ_1G);
> > + if (IS_ERR(mapping)) {
> > + ret = PTR_ERR(mapping);
> > + goto err_config_cleanup;
> > + }
> > +
> > + dma_set_coherent_mask(dev, DMA_BIT_MASK(32));
>
> This is the default coherent mask. If you call this function, you
> should normally check the return value, or call dma_set_mask first,
> which you apparently don't do here, and in another place in this
> patch.
By "This is the default mask" do you mean it shouldn't be called at
all ? Cause I ran into some trouble when not calling this in my
atmel-hlcdc driver.
Actually, in my case the platform device is created by the MFD core
which seems to let the coherent_dma_mask uninitialized.
Best Regards,
Boris
--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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