diff mbox series

[v3,1/3] drm/display: add transparent bridge helper

Message ID 20230802011845.4176631-2-dmitry.baryshkov@linaro.org (mailing list archive)
State New, archived
Headers show
Series drm/display: simplify support for transparent DRM bridges | expand

Commit Message

Dmitry Baryshkov Aug. 2, 2023, 1:18 a.m. UTC 
Define a helper for creating simple transparent bridges which serve the
only purpose of linking devices into the bridge chain up to the last
bridge representing the connector. This is especially useful for
DP/USB-C bridge chains, which can span across several devices, but do
not require any additional functionality from the intermediate bridges.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/display/Kconfig             |   9 ++
 drivers/gpu/drm/display/Makefile            |   2 +
 drivers/gpu/drm/display/drm_simple_bridge.c | 127 ++++++++++++++++++++
 include/drm/display/drm_simple_bridge.h     |  19 +++
 4 files changed, 157 insertions(+)
 create mode 100644 drivers/gpu/drm/display/drm_simple_bridge.c
 create mode 100644 include/drm/display/drm_simple_bridge.h

Comments

Neil Armstrong Aug. 2, 2023, 8:08 a.m. UTC | #1 
Hi Dmitry,

On 02/08/2023 03:18, Dmitry Baryshkov wrote:
> Define a helper for creating simple transparent bridges which serve the
> only purpose of linking devices into the bridge chain up to the last
> bridge representing the connector. This is especially useful for
> DP/USB-C bridge chains, which can span across several devices, but do
> not require any additional functionality from the intermediate bridges.

Can you CC me on the whole patchset ?

Thanks,
Neil


<snip>
Neil Armstrong Aug. 2, 2023, 8:09 a.m. UTC | #2 
On 02/08/2023 10:08, Neil Armstrong wrote:
> Hi Dmitry,
> 
> On 02/08/2023 03:18, Dmitry Baryshkov wrote:
>> Define a helper for creating simple transparent bridges which serve the
>> only purpose of linking devices into the bridge chain up to the last
>> bridge representing the connector. This is especially useful for
>> DP/USB-C bridge chains, which can span across several devices, but do
>> not require any additional functionality from the intermediate bridges.
> 
> Can you CC me on the whole patchset ?

Oops I am... sorry for the noise...

> 
> Thanks,
> Neil
> 
> 
> <snip>
>
Neil Armstrong Aug. 2, 2023, 8:15 a.m. UTC | #3 
Hi,

On 02/08/2023 03:18, Dmitry Baryshkov wrote:
> Define a helper for creating simple transparent bridges which serve the
> only purpose of linking devices into the bridge chain up to the last
> bridge representing the connector. This is especially useful for
> DP/USB-C bridge chains, which can span across several devices, but do
> not require any additional functionality from the intermediate bridges.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>   drivers/gpu/drm/display/Kconfig             |   9 ++
>   drivers/gpu/drm/display/Makefile            |   2 +
>   drivers/gpu/drm/display/drm_simple_bridge.c | 127 ++++++++++++++++++++

I wonder why drm/display/ and not drm/bridge ?

It's an helper, but it's mainly a bridge.

>   include/drm/display/drm_simple_bridge.h     |  19 +++
>   4 files changed, 157 insertions(+)
>   create mode 100644 drivers/gpu/drm/display/drm_simple_bridge.c
>   create mode 100644 include/drm/display/drm_simple_bridge.h
> 
> diff --git a/drivers/gpu/drm/display/Kconfig b/drivers/gpu/drm/display/Kconfig
> index 09712b88a5b8..a6132984b9e3 100644
> --- a/drivers/gpu/drm/display/Kconfig
> +++ b/drivers/gpu/drm/display/Kconfig
> @@ -49,3 +49,12 @@ config DRM_DP_CEC
>   
>   	  Note: not all adapters support this feature, and even for those
>   	  that do support this they often do not hook up the CEC pin.
> +
> +config DRM_SIMPLE_BRIDGE
> +	tristate
> +	depends on DRM
> +	select AUXILIARY_BUS
> +	select DRM_PANEL_BRIDGE
> +	help
> +	  Simple transparent bridge that is used by several drivers to build
> +	  bridges chain.
> diff --git a/drivers/gpu/drm/display/Makefile b/drivers/gpu/drm/display/Makefile
> index 17ac4a1006a8..6e2b0d7f24b3 100644
> --- a/drivers/gpu/drm/display/Makefile
> +++ b/drivers/gpu/drm/display/Makefile
> @@ -16,3 +16,5 @@ drm_display_helper-$(CONFIG_DRM_DP_AUX_CHARDEV) += drm_dp_aux_dev.o
>   drm_display_helper-$(CONFIG_DRM_DP_CEC) += drm_dp_cec.o
>   
>   obj-$(CONFIG_DRM_DISPLAY_HELPER) += drm_display_helper.o
> +
> +obj-$(CONFIG_DRM_SIMPLE_BRIDGE) += drm_simple_bridge.o
> diff --git a/drivers/gpu/drm/display/drm_simple_bridge.c b/drivers/gpu/drm/display/drm_simple_bridge.c
> new file mode 100644
> index 000000000000..9e80efe67b93
> --- /dev/null
> +++ b/drivers/gpu/drm/display/drm_simple_bridge.c
> @@ -0,0 +1,127 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2023 Linaro Ltd.
> + *
> + * Author: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> + */
> +#include <linux/auxiliary_bus.h>
> +#include <linux/module.h>
> +
> +#include <drm/drm_bridge.h>
> +#include <drm/display/drm_simple_bridge.h>
> +
> +static DEFINE_IDA(simple_bridge_ida);
> +
> +static void drm_simple_bridge_release(struct device *dev)
> +{
> +	struct auxiliary_device *adev = to_auxiliary_dev(dev);
> +
> +	kfree(adev);
> +}
> +
> +static void drm_simple_bridge_unregister_adev(void *_adev)
> +{
> +	struct auxiliary_device *adev = _adev;
> +
> +	auxiliary_device_delete(adev);
> +	auxiliary_device_uninit(adev);
> +}
> +
> +int drm_simple_bridge_register(struct device *parent)
> +{
> +	struct auxiliary_device *adev;
> +	int ret;
> +
> +	adev = kzalloc(sizeof(*adev), GFP_KERNEL);
> +	if (!adev)
> +		return -ENOMEM;
> +
> +	ret = ida_alloc(&simple_bridge_ida, GFP_KERNEL);
> +	if (ret < 0)
> +		return ret;
> +
> +	adev->id = ret;
> +	adev->name = "simple_bridge";
> +	adev->dev.parent = parent;
> +	adev->dev.of_node = parent->of_node;
> +	adev->dev.release = drm_simple_bridge_release;
> +
> +	ret = auxiliary_device_init(adev);
> +	if (ret) {
> +		kfree(adev);
> +		return ret;
> +	}
> +
> +	ret = auxiliary_device_add(adev);
> +	if (ret) {
> +		auxiliary_device_uninit(adev);
> +		return ret;
> +	}
> +
> +	return devm_add_action_or_reset(parent, drm_simple_bridge_unregister_adev, adev);
> +}
> +EXPORT_SYMBOL_GPL(drm_simple_bridge_register);
> +
> +struct drm_simple_bridge_data {
> +	struct drm_bridge bridge;
> +	struct drm_bridge *next_bridge;
> +	struct device *dev;
> +};
> +
> +static int drm_simple_bridge_attach(struct drm_bridge *bridge,
> +				    enum drm_bridge_attach_flags flags)
> +{
> +	struct drm_simple_bridge_data *data;
> +
> +	if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR))
> +		return -EINVAL;
> +
> +	data = container_of(bridge, struct drm_simple_bridge_data, bridge);
> +
> +	return drm_bridge_attach(bridge->encoder, data->next_bridge, bridge,
> +				 DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> +}
> +
> +static const struct drm_bridge_funcs drm_simple_bridge_funcs = {
> +	.attach	= drm_simple_bridge_attach,
> +};
> +
> +static int drm_simple_bridge_probe(struct auxiliary_device *auxdev,
> +				   const struct auxiliary_device_id *id)
> +{
> +	struct drm_simple_bridge_data *data;
> +
> +	data = devm_kzalloc(&auxdev->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->dev = &auxdev->dev;
> +	data->next_bridge = devm_drm_of_get_bridge(&auxdev->dev, auxdev->dev.of_node, 0, 0);
> +	if (IS_ERR(data->next_bridge))
> +		return dev_err_probe(&auxdev->dev, PTR_ERR(data->next_bridge),
> +				     "failed to acquire drm_bridge\n");
> +
> +	data->bridge.funcs = &drm_simple_bridge_funcs;
> +#ifdef CONFIG_OF
> +	data->bridge.of_node = data->dev->of_node;
> +#endif

I think the whole stuff should depend on OF since devm_drm_of_get_bridge() is a no-op when !OF

> +
> +	return devm_drm_bridge_add(data->dev, &data->bridge);
> +}
> +
> +static const struct auxiliary_device_id drm_simple_bridge_table[] = {
> +	{ .name = KBUILD_MODNAME ".simple_bridge" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(auxiliary, drm_simple_bridge_table);
> +
> +struct auxiliary_driver drm_simple_bridge_drv = {
> +	.name = "simple_bridge",
> +	.id_table = drm_simple_bridge_table,
> +	.probe = drm_simple_bridge_probe,
> +};
> +module_auxiliary_driver(drm_simple_bridge_drv);
> +
> +MODULE_AUTHOR("Dmitry Baryshkov <dmitry.baryshkov@linaro.org>");
> +MODULE_DESCRIPTION("DRM simple bridge helper");
> +MODULE_LICENSE("GPL");
> diff --git a/include/drm/display/drm_simple_bridge.h b/include/drm/display/drm_simple_bridge.h
> new file mode 100644
> index 000000000000..3da8e1fb1137
> --- /dev/null
> +++ b/include/drm/display/drm_simple_bridge.h
> @@ -0,0 +1,19 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2023 Linaro Ltd.
> + *
> + * Author: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> + */
> +#ifndef DRM_SIMPLE_BRIDGE_H
> +#define DRM_SIMPLE_BRIDGE_H
> +
> +#if IS_ENABLED(CONFIG_DRM_SIMPLE_BRIDGE)
> +int drm_simple_bridge_register(struct device *parent);
> +#else
> +static inline int drm_simple_bridge_register(struct device *parent)
> +{
> +	return 0;
> +}
> +#endif
> +
> +#endif

The design looks fine, but I'll need another review.

Thanks,
Neil
Dmitry Baryshkov Aug. 2, 2023, 9:12 a.m. UTC | #4 
On Wed, 2 Aug 2023 at 11:15, Neil Armstrong <neil.armstrong@linaro.org> wrote:
>
> Hi,
>
> On 02/08/2023 03:18, Dmitry Baryshkov wrote:
> > Define a helper for creating simple transparent bridges which serve the
> > only purpose of linking devices into the bridge chain up to the last
> > bridge representing the connector. This is especially useful for
> > DP/USB-C bridge chains, which can span across several devices, but do
> > not require any additional functionality from the intermediate bridges.
> >
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> > ---
> >   drivers/gpu/drm/display/Kconfig             |   9 ++
> >   drivers/gpu/drm/display/Makefile            |   2 +
> >   drivers/gpu/drm/display/drm_simple_bridge.c | 127 ++++++++++++++++++++
>
> I wonder why drm/display/ and not drm/bridge ?
>
> It's an helper, but it's mainly a bridge.

Why not? I'm open to any suggestions.

>
> >   include/drm/display/drm_simple_bridge.h     |  19 +++
> >   4 files changed, 157 insertions(+)
> >   create mode 100644 drivers/gpu/drm/display/drm_simple_bridge.c
> >   create mode 100644 include/drm/display/drm_simple_bridge.h
> >
> > diff --git a/drivers/gpu/drm/display/Kconfig b/drivers/gpu/drm/display/Kconfig
> > index 09712b88a5b8..a6132984b9e3 100644
> > --- a/drivers/gpu/drm/display/Kconfig
> > +++ b/drivers/gpu/drm/display/Kconfig
> > @@ -49,3 +49,12 @@ config DRM_DP_CEC
> >
> >         Note: not all adapters support this feature, and even for those
> >         that do support this they often do not hook up the CEC pin.
> > +
> > +config DRM_SIMPLE_BRIDGE
> > +     tristate
> > +     depends on DRM
> > +     select AUXILIARY_BUS
> > +     select DRM_PANEL_BRIDGE
> > +     help
> > +       Simple transparent bridge that is used by several drivers to build
> > +       bridges chain.
> > diff --git a/drivers/gpu/drm/display/Makefile b/drivers/gpu/drm/display/Makefile
> > index 17ac4a1006a8..6e2b0d7f24b3 100644
> > --- a/drivers/gpu/drm/display/Makefile
> > +++ b/drivers/gpu/drm/display/Makefile
> > @@ -16,3 +16,5 @@ drm_display_helper-$(CONFIG_DRM_DP_AUX_CHARDEV) += drm_dp_aux_dev.o
> >   drm_display_helper-$(CONFIG_DRM_DP_CEC) += drm_dp_cec.o
> >
> >   obj-$(CONFIG_DRM_DISPLAY_HELPER) += drm_display_helper.o
> > +
> > +obj-$(CONFIG_DRM_SIMPLE_BRIDGE) += drm_simple_bridge.o
> > diff --git a/drivers/gpu/drm/display/drm_simple_bridge.c b/drivers/gpu/drm/display/drm_simple_bridge.c
> > new file mode 100644
> > index 000000000000..9e80efe67b93
> > --- /dev/null
> > +++ b/drivers/gpu/drm/display/drm_simple_bridge.c
> > @@ -0,0 +1,127 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright (C) 2023 Linaro Ltd.
> > + *
> > + * Author: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> > + */
> > +#include <linux/auxiliary_bus.h>
> > +#include <linux/module.h>
> > +
> > +#include <drm/drm_bridge.h>
> > +#include <drm/display/drm_simple_bridge.h>
> > +
> > +static DEFINE_IDA(simple_bridge_ida);
> > +
> > +static void drm_simple_bridge_release(struct device *dev)
> > +{
> > +     struct auxiliary_device *adev = to_auxiliary_dev(dev);
> > +
> > +     kfree(adev);
> > +}
> > +
> > +static void drm_simple_bridge_unregister_adev(void *_adev)
> > +{
> > +     struct auxiliary_device *adev = _adev;
> > +
> > +     auxiliary_device_delete(adev);
> > +     auxiliary_device_uninit(adev);
> > +}
> > +
> > +int drm_simple_bridge_register(struct device *parent)
> > +{
> > +     struct auxiliary_device *adev;
> > +     int ret;
> > +
> > +     adev = kzalloc(sizeof(*adev), GFP_KERNEL);
> > +     if (!adev)
> > +             return -ENOMEM;
> > +
> > +     ret = ida_alloc(&simple_bridge_ida, GFP_KERNEL);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     adev->id = ret;
> > +     adev->name = "simple_bridge";
> > +     adev->dev.parent = parent;
> > +     adev->dev.of_node = parent->of_node;
> > +     adev->dev.release = drm_simple_bridge_release;
> > +
> > +     ret = auxiliary_device_init(adev);
> > +     if (ret) {
> > +             kfree(adev);
> > +             return ret;
> > +     }
> > +
> > +     ret = auxiliary_device_add(adev);
> > +     if (ret) {
> > +             auxiliary_device_uninit(adev);
> > +             return ret;
> > +     }
> > +
> > +     return devm_add_action_or_reset(parent, drm_simple_bridge_unregister_adev, adev);
> > +}
> > +EXPORT_SYMBOL_GPL(drm_simple_bridge_register);
> > +
> > +struct drm_simple_bridge_data {
> > +     struct drm_bridge bridge;
> > +     struct drm_bridge *next_bridge;
> > +     struct device *dev;
> > +};
> > +
> > +static int drm_simple_bridge_attach(struct drm_bridge *bridge,
> > +                                 enum drm_bridge_attach_flags flags)
> > +{
> > +     struct drm_simple_bridge_data *data;
> > +
> > +     if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR))
> > +             return -EINVAL;
> > +
> > +     data = container_of(bridge, struct drm_simple_bridge_data, bridge);
> > +
> > +     return drm_bridge_attach(bridge->encoder, data->next_bridge, bridge,
> > +                              DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> > +}
> > +
> > +static const struct drm_bridge_funcs drm_simple_bridge_funcs = {
> > +     .attach = drm_simple_bridge_attach,
> > +};
> > +
> > +static int drm_simple_bridge_probe(struct auxiliary_device *auxdev,
> > +                                const struct auxiliary_device_id *id)
> > +{
> > +     struct drm_simple_bridge_data *data;
> > +
> > +     data = devm_kzalloc(&auxdev->dev, sizeof(*data), GFP_KERNEL);
> > +     if (!data)
> > +             return -ENOMEM;
> > +
> > +     data->dev = &auxdev->dev;
> > +     data->next_bridge = devm_drm_of_get_bridge(&auxdev->dev, auxdev->dev.of_node, 0, 0);
> > +     if (IS_ERR(data->next_bridge))
> > +             return dev_err_probe(&auxdev->dev, PTR_ERR(data->next_bridge),
> > +                                  "failed to acquire drm_bridge\n");
> > +
> > +     data->bridge.funcs = &drm_simple_bridge_funcs;
> > +#ifdef CONFIG_OF
> > +     data->bridge.of_node = data->dev->of_node;
> > +#endif
>
> I think the whole stuff should depend on OF since devm_drm_of_get_bridge() is a no-op when !OF

Hmm, true. Probably we should rework bridges to use fwnode at some point.

>
> > +
> > +     return devm_drm_bridge_add(data->dev, &data->bridge);
> > +}
> > +
> > +static const struct auxiliary_device_id drm_simple_bridge_table[] = {
> > +     { .name = KBUILD_MODNAME ".simple_bridge" },
> > +     {},
> > +};
> > +MODULE_DEVICE_TABLE(auxiliary, drm_simple_bridge_table);
> > +
> > +struct auxiliary_driver drm_simple_bridge_drv = {
> > +     .name = "simple_bridge",
> > +     .id_table = drm_simple_bridge_table,
> > +     .probe = drm_simple_bridge_probe,
> > +};
> > +module_auxiliary_driver(drm_simple_bridge_drv);
> > +
> > +MODULE_AUTHOR("Dmitry Baryshkov <dmitry.baryshkov@linaro.org>");
> > +MODULE_DESCRIPTION("DRM simple bridge helper");
> > +MODULE_LICENSE("GPL");
> > diff --git a/include/drm/display/drm_simple_bridge.h b/include/drm/display/drm_simple_bridge.h
> > new file mode 100644
> > index 000000000000..3da8e1fb1137
> > --- /dev/null
> > +++ b/include/drm/display/drm_simple_bridge.h
> > @@ -0,0 +1,19 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright (C) 2023 Linaro Ltd.
> > + *
> > + * Author: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> > + */
> > +#ifndef DRM_SIMPLE_BRIDGE_H
> > +#define DRM_SIMPLE_BRIDGE_H
> > +
> > +#if IS_ENABLED(CONFIG_DRM_SIMPLE_BRIDGE)
> > +int drm_simple_bridge_register(struct device *parent);
> > +#else
> > +static inline int drm_simple_bridge_register(struct device *parent)
> > +{
> > +     return 0;
> > +}
> > +#endif
> > +
> > +#endif
>
> The design looks fine, but I'll need another review.
>
> Thanks,
> Neil
>
kernel test robot Aug. 6, 2023, 12:30 p.m. UTC | #5 
Hi Dmitry,

kernel test robot noticed the following build warnings:

[auto build test WARNING on drm-misc/drm-misc-next]
[also build test WARNING on usb/usb-testing usb/usb-next usb/usb-linus drm-intel/for-linux-next drm-intel/for-linux-next-fixes drm-tip/drm-tip linus/master v6.5-rc4 next-20230804]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Dmitry-Baryshkov/drm-display-add-transparent-bridge-helper/20230802-091932
base:   git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
patch link:    https://lore.kernel.org/r/20230802011845.4176631-2-dmitry.baryshkov%40linaro.org
patch subject: [PATCH v3 1/3] drm/display: add transparent bridge helper
config: i386-randconfig-r072-20230806 (https://download.01.org/0day-ci/archive/20230806/202308062017.iKU92hML-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce: (https://download.01.org/0day-ci/archive/20230806/202308062017.iKU92hML-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202308062017.iKU92hML-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> drivers/gpu/drm/display/drm_simple_bridge.c:118:25: sparse: sparse: symbol 'drm_simple_bridge_drv' was not declared. Should it be static?
Dan Carpenter Aug. 9, 2023, 7:58 a.m. UTC | #6 
Hi Dmitry,

kernel test robot noticed the following build warnings:

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Dmitry-Baryshkov/drm-display-add-transparent-bridge-helper/20230802-091932
base:   git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
patch link:    https://lore.kernel.org/r/20230802011845.4176631-2-dmitry.baryshkov%40linaro.org
patch subject: [PATCH v3 1/3] drm/display: add transparent bridge helper
config: x86_64-randconfig-m001-20230808 (https://download.01.org/0day-ci/archive/20230809/202308090559.RMlH2Dl6-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce: (https://download.01.org/0day-ci/archive/20230809/202308090559.RMlH2Dl6-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202308090559.RMlH2Dl6-lkp@intel.com/

smatch warnings:
drivers/gpu/drm/display/drm_simple_bridge.c:41 drm_simple_bridge_register() warn: possible memory leak of 'adev'

vim +/adev +41 drivers/gpu/drm/display/drm_simple_bridge.c

abf701043719cd Dmitry Baryshkov 2023-08-02  30  int drm_simple_bridge_register(struct device *parent)
abf701043719cd Dmitry Baryshkov 2023-08-02  31  {
abf701043719cd Dmitry Baryshkov 2023-08-02  32  	struct auxiliary_device *adev;
abf701043719cd Dmitry Baryshkov 2023-08-02  33  	int ret;
abf701043719cd Dmitry Baryshkov 2023-08-02  34  
abf701043719cd Dmitry Baryshkov 2023-08-02  35  	adev = kzalloc(sizeof(*adev), GFP_KERNEL);
abf701043719cd Dmitry Baryshkov 2023-08-02  36  	if (!adev)
abf701043719cd Dmitry Baryshkov 2023-08-02  37  		return -ENOMEM;
abf701043719cd Dmitry Baryshkov 2023-08-02  38  
abf701043719cd Dmitry Baryshkov 2023-08-02  39  	ret = ida_alloc(&simple_bridge_ida, GFP_KERNEL);
abf701043719cd Dmitry Baryshkov 2023-08-02  40  	if (ret < 0)
abf701043719cd Dmitry Baryshkov 2023-08-02 @41  		return ret;

kfree(adev);

abf701043719cd Dmitry Baryshkov 2023-08-02  42  
abf701043719cd Dmitry Baryshkov 2023-08-02  43  	adev->id = ret;
abf701043719cd Dmitry Baryshkov 2023-08-02  44  	adev->name = "simple_bridge";
abf701043719cd Dmitry Baryshkov 2023-08-02  45  	adev->dev.parent = parent;
abf701043719cd Dmitry Baryshkov 2023-08-02  46  	adev->dev.of_node = parent->of_node;
abf701043719cd Dmitry Baryshkov 2023-08-02  47  	adev->dev.release = drm_simple_bridge_release;
abf701043719cd Dmitry Baryshkov 2023-08-02  48  
abf701043719cd Dmitry Baryshkov 2023-08-02  49  	ret = auxiliary_device_init(adev);
abf701043719cd Dmitry Baryshkov 2023-08-02  50  	if (ret) {
abf701043719cd Dmitry Baryshkov 2023-08-02  51  		kfree(adev);

This needs to ida_free(&simple_bridge_ida, adev->id) as well.  There is
a smatch check for this (check_unwind.c) but I guess I plan to re-write
it a bit before I turn that on.

abf701043719cd Dmitry Baryshkov 2023-08-02  52  		return ret;
abf701043719cd Dmitry Baryshkov 2023-08-02  53  	}
abf701043719cd Dmitry Baryshkov 2023-08-02  54  
abf701043719cd Dmitry Baryshkov 2023-08-02  55  	ret = auxiliary_device_add(adev);
abf701043719cd Dmitry Baryshkov 2023-08-02  56  	if (ret) {
abf701043719cd Dmitry Baryshkov 2023-08-02  57  		auxiliary_device_uninit(adev);
abf701043719cd Dmitry Baryshkov 2023-08-02  58  		return ret;
abf701043719cd Dmitry Baryshkov 2023-08-02  59  	}
abf701043719cd Dmitry Baryshkov 2023-08-02  60  
abf701043719cd Dmitry Baryshkov 2023-08-02  61  	return devm_add_action_or_reset(parent, drm_simple_bridge_unregister_adev, adev);
abf701043719cd Dmitry Baryshkov 2023-08-02  62  }
diff mbox series

Patch

diff --git a/drivers/gpu/drm/display/Kconfig b/drivers/gpu/drm/display/Kconfig
index 09712b88a5b8..a6132984b9e3 100644
--- a/drivers/gpu/drm/display/Kconfig
+++ b/drivers/gpu/drm/display/Kconfig
@@ -49,3 +49,12 @@  config DRM_DP_CEC
 
 	  Note: not all adapters support this feature, and even for those
 	  that do support this they often do not hook up the CEC pin.
+
+config DRM_SIMPLE_BRIDGE
+	tristate
+	depends on DRM
+	select AUXILIARY_BUS
+	select DRM_PANEL_BRIDGE
+	help
+	  Simple transparent bridge that is used by several drivers to build
+	  bridges chain.
diff --git a/drivers/gpu/drm/display/Makefile b/drivers/gpu/drm/display/Makefile
index 17ac4a1006a8..6e2b0d7f24b3 100644
--- a/drivers/gpu/drm/display/Makefile
+++ b/drivers/gpu/drm/display/Makefile
@@ -16,3 +16,5 @@  drm_display_helper-$(CONFIG_DRM_DP_AUX_CHARDEV) += drm_dp_aux_dev.o
 drm_display_helper-$(CONFIG_DRM_DP_CEC) += drm_dp_cec.o
 
 obj-$(CONFIG_DRM_DISPLAY_HELPER) += drm_display_helper.o
+
+obj-$(CONFIG_DRM_SIMPLE_BRIDGE) += drm_simple_bridge.o
diff --git a/drivers/gpu/drm/display/drm_simple_bridge.c b/drivers/gpu/drm/display/drm_simple_bridge.c
new file mode 100644
index 000000000000..9e80efe67b93
--- /dev/null
+++ b/drivers/gpu/drm/display/drm_simple_bridge.c
@@ -0,0 +1,127 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2023 Linaro Ltd.
+ *
+ * Author: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
+ */
+#include <linux/auxiliary_bus.h>
+#include <linux/module.h>
+
+#include <drm/drm_bridge.h>
+#include <drm/display/drm_simple_bridge.h>
+
+static DEFINE_IDA(simple_bridge_ida);
+
+static void drm_simple_bridge_release(struct device *dev)
+{
+	struct auxiliary_device *adev = to_auxiliary_dev(dev);
+
+	kfree(adev);
+}
+
+static void drm_simple_bridge_unregister_adev(void *_adev)
+{
+	struct auxiliary_device *adev = _adev;
+
+	auxiliary_device_delete(adev);
+	auxiliary_device_uninit(adev);
+}
+
+int drm_simple_bridge_register(struct device *parent)
+{
+	struct auxiliary_device *adev;
+	int ret;
+
+	adev = kzalloc(sizeof(*adev), GFP_KERNEL);
+	if (!adev)
+		return -ENOMEM;
+
+	ret = ida_alloc(&simple_bridge_ida, GFP_KERNEL);
+	if (ret < 0)
+		return ret;
+
+	adev->id = ret;
+	adev->name = "simple_bridge";
+	adev->dev.parent = parent;
+	adev->dev.of_node = parent->of_node;
+	adev->dev.release = drm_simple_bridge_release;
+
+	ret = auxiliary_device_init(adev);
+	if (ret) {
+		kfree(adev);
+		return ret;
+	}
+
+	ret = auxiliary_device_add(adev);
+	if (ret) {
+		auxiliary_device_uninit(adev);
+		return ret;
+	}
+
+	return devm_add_action_or_reset(parent, drm_simple_bridge_unregister_adev, adev);
+}
+EXPORT_SYMBOL_GPL(drm_simple_bridge_register);
+
+struct drm_simple_bridge_data {
+	struct drm_bridge bridge;
+	struct drm_bridge *next_bridge;
+	struct device *dev;
+};
+
+static int drm_simple_bridge_attach(struct drm_bridge *bridge,
+				    enum drm_bridge_attach_flags flags)
+{
+	struct drm_simple_bridge_data *data;
+
+	if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR))
+		return -EINVAL;
+
+	data = container_of(bridge, struct drm_simple_bridge_data, bridge);
+
+	return drm_bridge_attach(bridge->encoder, data->next_bridge, bridge,
+				 DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+}
+
+static const struct drm_bridge_funcs drm_simple_bridge_funcs = {
+	.attach	= drm_simple_bridge_attach,
+};
+
+static int drm_simple_bridge_probe(struct auxiliary_device *auxdev,
+				   const struct auxiliary_device_id *id)
+{
+	struct drm_simple_bridge_data *data;
+
+	data = devm_kzalloc(&auxdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->dev = &auxdev->dev;
+	data->next_bridge = devm_drm_of_get_bridge(&auxdev->dev, auxdev->dev.of_node, 0, 0);
+	if (IS_ERR(data->next_bridge))
+		return dev_err_probe(&auxdev->dev, PTR_ERR(data->next_bridge),
+				     "failed to acquire drm_bridge\n");
+
+	data->bridge.funcs = &drm_simple_bridge_funcs;
+#ifdef CONFIG_OF
+	data->bridge.of_node = data->dev->of_node;
+#endif
+
+	return devm_drm_bridge_add(data->dev, &data->bridge);
+}
+
+static const struct auxiliary_device_id drm_simple_bridge_table[] = {
+	{ .name = KBUILD_MODNAME ".simple_bridge" },
+	{},
+};
+MODULE_DEVICE_TABLE(auxiliary, drm_simple_bridge_table);
+
+struct auxiliary_driver drm_simple_bridge_drv = {
+	.name = "simple_bridge",
+	.id_table = drm_simple_bridge_table,
+	.probe = drm_simple_bridge_probe,
+};
+module_auxiliary_driver(drm_simple_bridge_drv);
+
+MODULE_AUTHOR("Dmitry Baryshkov <dmitry.baryshkov@linaro.org>");
+MODULE_DESCRIPTION("DRM simple bridge helper");
+MODULE_LICENSE("GPL");
diff --git a/include/drm/display/drm_simple_bridge.h b/include/drm/display/drm_simple_bridge.h
new file mode 100644
index 000000000000..3da8e1fb1137
--- /dev/null
+++ b/include/drm/display/drm_simple_bridge.h
@@ -0,0 +1,19 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2023 Linaro Ltd.
+ *
+ * Author: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
+ */
+#ifndef DRM_SIMPLE_BRIDGE_H
+#define DRM_SIMPLE_BRIDGE_H
+
+#if IS_ENABLED(CONFIG_DRM_SIMPLE_BRIDGE)
+int drm_simple_bridge_register(struct device *parent);
+#else
+static inline int drm_simple_bridge_register(struct device *parent)
+{
+	return 0;
+}
+#endif
+
+#endif