The GPU subsystem node was a workaround to have a central device to
bind V3D and display to. Following the lead of 246774d17fc0
("drm/etnaviv: remove the need for a gpu-subsystem DT node"), remove
the subsystem node usage and just create a platform device for the DRM
device to attach to if any of the subsystem devices are present.
Signed-off-by: Eric Anholt <[email protected]>
---
.../bindings/display/brcm,bcm-vc4.txt | 7 ----
drivers/gpu/drm/vc4/vc4_drv.c | 33 ++++++++++++++-----
drivers/gpu/drm/vc4/vc4_hvs.c | 1 +
drivers/gpu/drm/vc4/vc4_v3d.c | 1 +
4 files changed, 27 insertions(+), 15 deletions(-)
diff --git a/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt b/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
index 284e2b14cfbe..5fd4717101d6 100644
--- a/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
+++ b/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
@@ -4,9 +4,6 @@ The VC4 device present on the Raspberry Pi includes a display system
with HDMI output and the HVS (Hardware Video Scaler) for compositing
display planes.
-Required properties for VC4:
-- compatible: Should be "brcm,bcm2835-vc4" or "brcm,cygnus-vc4"
-
Required properties for Pixel Valve:
- compatible: Should be one of "brcm,bcm2835-pixelvalve0",
"brcm,bcm2835-pixelvalve1", or "brcm,bcm2835-pixelvalve2"
@@ -153,10 +150,6 @@ v3d: v3d@7ec00000 {
interrupts = <1 10>;
};
-vc4: gpu {
- compatible = "brcm,bcm2835-vc4";
-};
-
panel: panel {
compatible = "ontat,yx700wv03", "simple-panel";
diff --git a/drivers/gpu/drm/vc4/vc4_drv.c b/drivers/gpu/drm/vc4/vc4_drv.c
index 7c95ed5c5cac..d282ab7de03a 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.c
+++ b/drivers/gpu/drm/vc4/vc4_drv.c
@@ -364,22 +364,34 @@ static int vc4_platform_drm_remove(struct platform_device *pdev)
return 0;
}
-static const struct of_device_id vc4_of_match[] = {
- { .compatible = "brcm,bcm2835-vc4", },
- { .compatible = "brcm,cygnus-vc4", },
- {},
-};
-MODULE_DEVICE_TABLE(of, vc4_of_match);
-
static struct platform_driver vc4_platform_driver = {
.probe = vc4_platform_drm_probe,
.remove = vc4_platform_drm_remove,
.driver = {
.name = "vc4-drm",
- .of_match_table = vc4_of_match,
},
};
+static bool
+driver_of_table_has_a_match(const struct platform_driver *driver)
+{
+ int i;
+
+ for (i = 0; driver->driver.of_match_table[i].compatible; i++) {
+ const char *compat = driver->driver.of_match_table[i].compatible;
+ struct device_node *node;
+
+ while ((node = of_find_compatible_node(node, NULL, compat))) {
+ if (of_device_is_available(node)) {
+ of_node_put(node);
+ return true;
+ }
+ }
+ }
+
+ return false;
+}
+
static int __init vc4_drm_register(void)
{
int ret;
@@ -389,6 +401,11 @@ static int __init vc4_drm_register(void)
if (ret)
return ret;
+ if (driver_of_table_has_a_match(&vc4_v3d_driver) ||
+ driver_of_table_has_a_match(&vc4_hvs_driver)) {
+ platform_device_register_simple("vc4-drm", -1, NULL, 0);
+ }
+
return platform_driver_register(&vc4_platform_driver);
}
diff --git a/drivers/gpu/drm/vc4/vc4_hvs.c b/drivers/gpu/drm/vc4/vc4_hvs.c
index 2b62fc5b8d85..730813ee74ae 100644
--- a/drivers/gpu/drm/vc4/vc4_hvs.c
+++ b/drivers/gpu/drm/vc4/vc4_hvs.c
@@ -262,6 +262,7 @@ static const struct of_device_id vc4_hvs_dt_match[] = {
{ .compatible = "brcm,bcm2835-hvs" },
{}
};
+MODULE_DEVICE_TABLE(of, vc4_hvs_dt_match);
struct platform_driver vc4_hvs_driver = {
.probe = vc4_hvs_dev_probe,
diff --git a/drivers/gpu/drm/vc4/vc4_v3d.c b/drivers/gpu/drm/vc4/vc4_v3d.c
index bfc2fa73d2ae..e77e9ebbab4b 100644
--- a/drivers/gpu/drm/vc4/vc4_v3d.c
+++ b/drivers/gpu/drm/vc4/vc4_v3d.c
@@ -459,6 +459,7 @@ static const struct of_device_id vc4_v3d_dt_match[] = {
{ .compatible = "brcm,vc4-v3d" },
{}
};
+MODULE_DEVICE_TABLE(of, vc4_v3d_dt_match);
struct platform_driver vc4_v3d_driver = {
.probe = vc4_v3d_dev_probe,
--
2.17.0
This is no longer required by the DRM driver, and was just a temporary
hack for it.
Signed-off-by: Eric Anholt <[email protected]>
---
arch/arm/boot/dts/bcm283x.dtsi | 4 ----
1 file changed, 4 deletions(-)
diff --git a/arch/arm/boot/dts/bcm283x.dtsi b/arch/arm/boot/dts/bcm283x.dtsi
index 9d293decf8d3..869bf350d426 100644
--- a/arch/arm/boot/dts/bcm283x.dtsi
+++ b/arch/arm/boot/dts/bcm283x.dtsi
@@ -609,10 +609,6 @@
reg = <0x7ec00000 0x1000>;
interrupts = <1 10>;
};
-
- vc4: gpu {
- compatible = "brcm,bcm2835-vc4";
- };
};
clocks {
--
2.17.0
This is no longer required by the DRM driver, and was just a temporary
hack for it.
Signed-off-by: Eric Anholt <[email protected]>
---
arch/arm/boot/dts/bcm-cygnus.dtsi | 4 ----
1 file changed, 4 deletions(-)
diff --git a/arch/arm/boot/dts/bcm-cygnus.dtsi b/arch/arm/boot/dts/bcm-cygnus.dtsi
index 699fdf94d139..258bb3d61582 100644
--- a/arch/arm/boot/dts/bcm-cygnus.dtsi
+++ b/arch/arm/boot/dts/bcm-cygnus.dtsi
@@ -492,10 +492,6 @@
status = "disabled";
};
- vc4: gpu {
- compatible = "brcm,cygnus-vc4";
- };
-
gpio_asiu: gpio@180a5000 {
compatible = "brcm,cygnus-asiu-gpio";
reg = <0x180a5000 0x668>;
--
2.17.0
Hi Eric,
> Eric Anholt <[email protected]> hat am 10. April 2018 um 01:00 geschrieben:
>
>
> The GPU subsystem node was a workaround to have a central device to
> bind V3D and display to. Following the lead of 246774d17fc0
> ("drm/etnaviv: remove the need for a gpu-subsystem DT node"), remove
> the subsystem node usage and just create a platform device for the DRM
> device to attach to if any of the subsystem devices are present.
i didn't test it. Does the code change keep the backward compatibility with older DT?
Stefan Wahren <[email protected]> writes:
> Hi Eric,
>
>> Eric Anholt <[email protected]> hat am 10. April 2018 um 01:00 geschrieben:
>>
>>
>> The GPU subsystem node was a workaround to have a central device to
>> bind V3D and display to. Following the lead of 246774d17fc0
>> ("drm/etnaviv: remove the need for a gpu-subsystem DT node"), remove
>> the subsystem node usage and just create a platform device for the DRM
>> device to attach to if any of the subsystem devices are present.
>
> i didn't test it. Does the code change keep the backward compatibility with older DT?
Yes.
On Mon, Apr 09, 2018 at 04:00:38PM -0700, Eric Anholt wrote:
> The GPU subsystem node was a workaround to have a central device to
> bind V3D and display to. Following the lead of 246774d17fc0
> ("drm/etnaviv: remove the need for a gpu-subsystem DT node"), remove
> the subsystem node usage and just create a platform device for the DRM
> device to attach to if any of the subsystem devices are present.
>
> Signed-off-by: Eric Anholt <[email protected]>
> ---
> .../bindings/display/brcm,bcm-vc4.txt | 7 ----
> drivers/gpu/drm/vc4/vc4_drv.c | 33 ++++++++++++++-----
> drivers/gpu/drm/vc4/vc4_hvs.c | 1 +
> drivers/gpu/drm/vc4/vc4_v3d.c | 1 +
> 4 files changed, 27 insertions(+), 15 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt b/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
> index 284e2b14cfbe..5fd4717101d6 100644
> --- a/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
> +++ b/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
> @@ -4,9 +4,6 @@ The VC4 device present on the Raspberry Pi includes a display system
> with HDMI output and the HVS (Hardware Video Scaler) for compositing
> display planes.
>
> -Required properties for VC4:
> -- compatible: Should be "brcm,bcm2835-vc4" or "brcm,cygnus-vc4"
> -
> Required properties for Pixel Valve:
> - compatible: Should be one of "brcm,bcm2835-pixelvalve0",
> "brcm,bcm2835-pixelvalve1", or "brcm,bcm2835-pixelvalve2"
> @@ -153,10 +150,6 @@ v3d: v3d@7ec00000 {
> interrupts = <1 10>;
> };
>
> -vc4: gpu {
> - compatible = "brcm,bcm2835-vc4";
> -};
> -
> panel: panel {
> compatible = "ontat,yx700wv03", "simple-panel";
>
> diff --git a/drivers/gpu/drm/vc4/vc4_drv.c b/drivers/gpu/drm/vc4/vc4_drv.c
> index 7c95ed5c5cac..d282ab7de03a 100644
> --- a/drivers/gpu/drm/vc4/vc4_drv.c
> +++ b/drivers/gpu/drm/vc4/vc4_drv.c
> @@ -364,22 +364,34 @@ static int vc4_platform_drm_remove(struct platform_device *pdev)
> return 0;
> }
>
> -static const struct of_device_id vc4_of_match[] = {
> - { .compatible = "brcm,bcm2835-vc4", },
> - { .compatible = "brcm,cygnus-vc4", },
> - {},
> -};
> -MODULE_DEVICE_TABLE(of, vc4_of_match);
> -
> static struct platform_driver vc4_platform_driver = {
> .probe = vc4_platform_drm_probe,
> .remove = vc4_platform_drm_remove,
> .driver = {
> .name = "vc4-drm",
> - .of_match_table = vc4_of_match,
> },
> };
>
> +static bool
> +driver_of_table_has_a_match(const struct platform_driver *driver)
> +{
> + int i;
> +
> + for (i = 0; driver->driver.of_match_table[i].compatible; i++) {
> + const char *compat = driver->driver.of_match_table[i].compatible;
> + struct device_node *node;
> +
> + while ((node = of_find_compatible_node(node, NULL, compat))) {
> + if (of_device_is_available(node)) {
> + of_node_put(node);
> + return true;
> + }
> + }
> + }
All this can be replaced with:
node = of_find_matching_node_and_match(NULL, driver->driver.of_match_table, NULL);
if (of_device_is_available(node)) {
of_node_put(node);
return true;
}
> +
> + return false;
> +}
> +
The GPU subsystem node was a workaround to have a central device to
bind V3D and display to. Following the lead of 246774d17fc0
("drm/etnaviv: remove the need for a gpu-subsystem DT node"), remove
the subsystem node usage and just create a platform device for the DRM
device to attach to if any of the subsystem devices are present.
v2: Simplify the DT walking code.
Signed-off-by: Eric Anholt <[email protected]>
---
.../bindings/display/brcm,bcm-vc4.txt | 7 -----
drivers/gpu/drm/vc4/vc4_drv.c | 29 ++++++++++++++-----
drivers/gpu/drm/vc4/vc4_hvs.c | 1 +
drivers/gpu/drm/vc4/vc4_v3d.c | 1 +
4 files changed, 23 insertions(+), 15 deletions(-)
diff --git a/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt b/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
index 284e2b14cfbe..5fd4717101d6 100644
--- a/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
+++ b/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
@@ -4,9 +4,6 @@ The VC4 device present on the Raspberry Pi includes a display system
with HDMI output and the HVS (Hardware Video Scaler) for compositing
display planes.
-Required properties for VC4:
-- compatible: Should be "brcm,bcm2835-vc4" or "brcm,cygnus-vc4"
-
Required properties for Pixel Valve:
- compatible: Should be one of "brcm,bcm2835-pixelvalve0",
"brcm,bcm2835-pixelvalve1", or "brcm,bcm2835-pixelvalve2"
@@ -153,10 +150,6 @@ v3d: v3d@7ec00000 {
interrupts = <1 10>;
};
-vc4: gpu {
- compatible = "brcm,bcm2835-vc4";
-};
-
panel: panel {
compatible = "ontat,yx700wv03", "simple-panel";
diff --git a/drivers/gpu/drm/vc4/vc4_drv.c b/drivers/gpu/drm/vc4/vc4_drv.c
index 7c95ed5c5cac..13b840b534b8 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.c
+++ b/drivers/gpu/drm/vc4/vc4_drv.c
@@ -364,22 +364,30 @@ static int vc4_platform_drm_remove(struct platform_device *pdev)
return 0;
}
-static const struct of_device_id vc4_of_match[] = {
- { .compatible = "brcm,bcm2835-vc4", },
- { .compatible = "brcm,cygnus-vc4", },
- {},
-};
-MODULE_DEVICE_TABLE(of, vc4_of_match);
-
static struct platform_driver vc4_platform_driver = {
.probe = vc4_platform_drm_probe,
.remove = vc4_platform_drm_remove,
.driver = {
.name = "vc4-drm",
- .of_match_table = vc4_of_match,
},
};
+static bool
+driver_of_table_has_a_match(const struct platform_driver *driver)
+{
+ struct device_node *node;
+
+ node = of_find_matching_node_and_match(NULL,
+ driver->driver.of_match_table,
+ NULL);
+ if (of_device_is_available(node)) {
+ of_node_put(node);
+ return true;
+ }
+
+ return false;
+}
+
static int __init vc4_drm_register(void)
{
int ret;
@@ -389,6 +397,11 @@ static int __init vc4_drm_register(void)
if (ret)
return ret;
+ if (driver_of_table_has_a_match(&vc4_v3d_driver) ||
+ driver_of_table_has_a_match(&vc4_hvs_driver)) {
+ platform_device_register_simple("vc4-drm", -1, NULL, 0);
+ }
+
return platform_driver_register(&vc4_platform_driver);
}
diff --git a/drivers/gpu/drm/vc4/vc4_hvs.c b/drivers/gpu/drm/vc4/vc4_hvs.c
index 2b62fc5b8d85..730813ee74ae 100644
--- a/drivers/gpu/drm/vc4/vc4_hvs.c
+++ b/drivers/gpu/drm/vc4/vc4_hvs.c
@@ -262,6 +262,7 @@ static const struct of_device_id vc4_hvs_dt_match[] = {
{ .compatible = "brcm,bcm2835-hvs" },
{}
};
+MODULE_DEVICE_TABLE(of, vc4_hvs_dt_match);
struct platform_driver vc4_hvs_driver = {
.probe = vc4_hvs_dev_probe,
diff --git a/drivers/gpu/drm/vc4/vc4_v3d.c b/drivers/gpu/drm/vc4/vc4_v3d.c
index bfc2fa73d2ae..e77e9ebbab4b 100644
--- a/drivers/gpu/drm/vc4/vc4_v3d.c
+++ b/drivers/gpu/drm/vc4/vc4_v3d.c
@@ -459,6 +459,7 @@ static const struct of_device_id vc4_v3d_dt_match[] = {
{ .compatible = "brcm,vc4-v3d" },
{}
};
+MODULE_DEVICE_TABLE(of, vc4_v3d_dt_match);
struct platform_driver vc4_v3d_driver = {
.probe = vc4_v3d_dev_probe,
--
2.17.0
On Mon, Apr 16, 2018 at 12:25 PM, Eric Anholt <[email protected]> wrote:
> The GPU subsystem node was a workaround to have a central device to
> bind V3D and display to. Following the lead of 246774d17fc0
> ("drm/etnaviv: remove the need for a gpu-subsystem DT node"), remove
> the subsystem node usage and just create a platform device for the DRM
> device to attach to if any of the subsystem devices are present.
>
> v2: Simplify the DT walking code.
> +static bool
> +driver_of_table_has_a_match(const struct platform_driver *driver)
> +{
> + struct device_node *node;
> +
> + node = of_find_matching_node_and_match(NULL,
> + driver->driver.of_match_table,
> + NULL);
> + if (of_device_is_available(node)) {
> + of_node_put(node);
You need to put the node regardless.
> + return true;
> + }
> +
> + return false;
> +}
The GPU subsystem node was a workaround to have a central device to
bind V3D and display to. Following the lead of 246774d17fc0
("drm/etnaviv: remove the need for a gpu-subsystem DT node"), remove
the subsystem node usage and just create a platform device for the DRM
device to attach to if any of the subsystem devices are present.
v2: Simplify the DT walking code.
v3: Always put the node.
Signed-off-by: Eric Anholt <[email protected]>
---
.../bindings/display/brcm,bcm-vc4.txt | 7 -----
drivers/gpu/drm/vc4/vc4_drv.c | 28 +++++++++++++------
drivers/gpu/drm/vc4/vc4_hvs.c | 1 +
drivers/gpu/drm/vc4/vc4_v3d.c | 1 +
4 files changed, 22 insertions(+), 15 deletions(-)
diff --git a/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt b/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
index 284e2b14cfbe..5fd4717101d6 100644
--- a/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
+++ b/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
@@ -4,9 +4,6 @@ The VC4 device present on the Raspberry Pi includes a display system
with HDMI output and the HVS (Hardware Video Scaler) for compositing
display planes.
-Required properties for VC4:
-- compatible: Should be "brcm,bcm2835-vc4" or "brcm,cygnus-vc4"
-
Required properties for Pixel Valve:
- compatible: Should be one of "brcm,bcm2835-pixelvalve0",
"brcm,bcm2835-pixelvalve1", or "brcm,bcm2835-pixelvalve2"
@@ -153,10 +150,6 @@ v3d: v3d@7ec00000 {
interrupts = <1 10>;
};
-vc4: gpu {
- compatible = "brcm,bcm2835-vc4";
-};
-
panel: panel {
compatible = "ontat,yx700wv03", "simple-panel";
diff --git a/drivers/gpu/drm/vc4/vc4_drv.c b/drivers/gpu/drm/vc4/vc4_drv.c
index 7c95ed5c5cac..e8ba9e7c71d2 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.c
+++ b/drivers/gpu/drm/vc4/vc4_drv.c
@@ -364,22 +364,29 @@ static int vc4_platform_drm_remove(struct platform_device *pdev)
return 0;
}
-static const struct of_device_id vc4_of_match[] = {
- { .compatible = "brcm,bcm2835-vc4", },
- { .compatible = "brcm,cygnus-vc4", },
- {},
-};
-MODULE_DEVICE_TABLE(of, vc4_of_match);
-
static struct platform_driver vc4_platform_driver = {
.probe = vc4_platform_drm_probe,
.remove = vc4_platform_drm_remove,
.driver = {
.name = "vc4-drm",
- .of_match_table = vc4_of_match,
},
};
+static bool
+driver_of_table_has_a_match(const struct platform_driver *driver)
+{
+ struct device_node *node;
+ bool ret;
+
+ node = of_find_matching_node_and_match(NULL,
+ driver->driver.of_match_table,
+ NULL);
+ ret = of_device_is_available(node);
+ of_node_put(node);
+
+ return ret;
+}
+
static int __init vc4_drm_register(void)
{
int ret;
@@ -389,6 +396,11 @@ static int __init vc4_drm_register(void)
if (ret)
return ret;
+ if (driver_of_table_has_a_match(&vc4_v3d_driver) ||
+ driver_of_table_has_a_match(&vc4_hvs_driver)) {
+ platform_device_register_simple("vc4-drm", -1, NULL, 0);
+ }
+
return platform_driver_register(&vc4_platform_driver);
}
diff --git a/drivers/gpu/drm/vc4/vc4_hvs.c b/drivers/gpu/drm/vc4/vc4_hvs.c
index 2b62fc5b8d85..730813ee74ae 100644
--- a/drivers/gpu/drm/vc4/vc4_hvs.c
+++ b/drivers/gpu/drm/vc4/vc4_hvs.c
@@ -262,6 +262,7 @@ static const struct of_device_id vc4_hvs_dt_match[] = {
{ .compatible = "brcm,bcm2835-hvs" },
{}
};
+MODULE_DEVICE_TABLE(of, vc4_hvs_dt_match);
struct platform_driver vc4_hvs_driver = {
.probe = vc4_hvs_dev_probe,
diff --git a/drivers/gpu/drm/vc4/vc4_v3d.c b/drivers/gpu/drm/vc4/vc4_v3d.c
index bfc2fa73d2ae..e77e9ebbab4b 100644
--- a/drivers/gpu/drm/vc4/vc4_v3d.c
+++ b/drivers/gpu/drm/vc4/vc4_v3d.c
@@ -459,6 +459,7 @@ static const struct of_device_id vc4_v3d_dt_match[] = {
{ .compatible = "brcm,vc4-v3d" },
{}
};
+MODULE_DEVICE_TABLE(of, vc4_v3d_dt_match);
struct platform_driver vc4_v3d_driver = {
.probe = vc4_v3d_dev_probe,
--
2.17.0
On Mon, Apr 16, 2018 at 5:52 PM, Eric Anholt <[email protected]> wrote:
> The GPU subsystem node was a workaround to have a central device to
> bind V3D and display to. Following the lead of 246774d17fc0
> ("drm/etnaviv: remove the need for a gpu-subsystem DT node"), remove
> the subsystem node usage and just create a platform device for the DRM
> device to attach to if any of the subsystem devices are present.
>
> v2: Simplify the DT walking code.
> v3: Always put the node.
>
> Signed-off-by: Eric Anholt <[email protected]>
> ---
> .../bindings/display/brcm,bcm-vc4.txt | 7 -----
> drivers/gpu/drm/vc4/vc4_drv.c | 28 +++++++++++++------
> drivers/gpu/drm/vc4/vc4_hvs.c | 1 +
> drivers/gpu/drm/vc4/vc4_v3d.c | 1 +
> 4 files changed, 22 insertions(+), 15 deletions(-)
Reviewed-by: Rob Herring <[email protected]>
Rob Herring <[email protected]> writes:
> On Mon, Apr 16, 2018 at 5:52 PM, Eric Anholt <[email protected]> wrote:
>> The GPU subsystem node was a workaround to have a central device to
>> bind V3D and display to. Following the lead of 246774d17fc0
>> ("drm/etnaviv: remove the need for a gpu-subsystem DT node"), remove
>> the subsystem node usage and just create a platform device for the DRM
>> device to attach to if any of the subsystem devices are present.
>>
>> v2: Simplify the DT walking code.
>> v3: Always put the node.
>>
>> Signed-off-by: Eric Anholt <[email protected]>
>> ---
>> .../bindings/display/brcm,bcm-vc4.txt | 7 -----
>> drivers/gpu/drm/vc4/vc4_drv.c | 28 +++++++++++++------
>> drivers/gpu/drm/vc4/vc4_hvs.c | 1 +
>> drivers/gpu/drm/vc4/vc4_v3d.c | 1 +
>> 4 files changed, 22 insertions(+), 15 deletions(-)
>
> Reviewed-by: Rob Herring <[email protected]>
Unfortunately, on further testing, this ends up broken. My guess is
that our new platform device isn't on the same bus, so we don't get our
dma-ranges translation when we use drm->dev, and that breaks caching
behavior.