Re: [PATCH v3 01/22] drm: Include ddc adapter pointer in struct drm_connector
On 01.07.2019 16:41, Thomas Zimmermann wrote:
> Hi
>
> Am 01.07.19 um 15:27 schrieb Andrzej Pietrasiewicz:
>> Hi Thomas,
>>
>> Thank you for your comments. Please see inline.
>>
>> W dniu 30.06.2019 o 10:12, Thomas Zimmermann pisze:
>>> Hi
>>>
>>> I like the idea, but would prefer a more structured approach.
>>>
>>> Setting connector->ddc before calling drm_sysfs_connector_add() seems
>>> error prone. The dependency is not really clear from the code or
>>> interfaces.
>>>
>>> The other thing is that drivers I mostly work on, ast and mgag200, have
>>> code like this:
>>>
>>> struct ast_i2c_chan {
>>> struct i2c_adapter adapter;
>>> struct drm_device *dev;
>>> struct i2c_algo_bit_data bit;
>>> };
>>>
>>> struct ast_connector {
>>> struct drm_connector base;
>>> struct ast_i2c_chan *i2c;
>>> };
>>>
>>> It already encodes the connection between connector and ddc adapter.
>>>
>>> I suggest to introduce struct drm_i2c_adapter
>>>
>>> struct drm_i2c_adapter {
>>> struct i2c_adapter base;
>>> struct drm_connector *connector;
>>> };
>>>
>>> and convert drivers over to it. Ast would look like this:
>>>
>>> struct ast_i2c_chan {
>>> struct drm_i2c_adapter adapter;
>>> struct i2c_algo_bit_data bit;
>>> };
>>>
>> There are few flavors of these drivers. In some of them
>> the i2c_adapter for ddc is allocated and initialized by
>> the driver, which must provide a place in memory to hold
>> the adapter. ast is an example of this approach.
>>
>> But there are others, such as for example exynos_hdmi.c.
>> It gets its ddc adapter with of_find_i2c_adapter_by_node()
>> and merely stores a pointer to it, while not managing the
>> memory needed to hold the i2c_adapter.
> I see.
>
>> Do you have any idea how to accommodate these various
>> flavors of drivers in the scheme you propose?
> Something like
>
> struct drm_i2c_adapter {
> struct i2c_adapter *adapter;
> struct drm_connector *connector;
> };
>
> with adapter either being allocated dynamically or acquired via
> of_find_i2c_adapter_by_node(); with separate init and finish functions
> for each variant. But it looks like over-abstraction to me. Without
> prototyping the idea, I cannot say if it's worth the effort.
>
> For something more simple, maybe just have a function to attach an i2c
> adapter to a connector:
>
> drm_connector_attach_i2c_adapter(connector, i2c_adapter)
>
> which sets the connector's ddc pointer and creates the sysfs entry if
> the connector's entry is already present.
I am not sure if such function is really necessary. Assigning ddc field
before connector registration seems to be much simpler and quite
standard - many fields are initialized this way.
Reviewed-by: Andrzej Hajda
--
Regards
Andrzej
> Best regards
> Thomas
>
>> Andrzej
>>
>>
Re: [PATCH v3 01/22] drm: Include ddc adapter pointer in struct drm_connector
Hi
Am 01.07.19 um 15:27 schrieb Andrzej Pietrasiewicz:
> Hi Thomas,
>
> Thank you for your comments. Please see inline.
>
> W dniu 30.06.2019 o 10:12, Thomas Zimmermann pisze:
>> Hi
>>
>> I like the idea, but would prefer a more structured approach.
>>
>> Setting connector->ddc before calling drm_sysfs_connector_add() seems
>> error prone. The dependency is not really clear from the code or
>> interfaces.
>>
>> The other thing is that drivers I mostly work on, ast and mgag200, have
>> code like this:
>>
>> struct ast_i2c_chan {
>> struct i2c_adapter adapter;
>> struct drm_device *dev;
>> struct i2c_algo_bit_data bit;
>> };
>>
>> struct ast_connector {
>> struct drm_connector base;
>> struct ast_i2c_chan *i2c;
>> };
>>
>> It already encodes the connection between connector and ddc adapter.
>>
>> I suggest to introduce struct drm_i2c_adapter
>>
>> struct drm_i2c_adapter {
>> struct i2c_adapter base;
>> struct drm_connector *connector;
>> };
>>
>> and convert drivers over to it. Ast would look like this:
>>
>> struct ast_i2c_chan {
>> struct drm_i2c_adapter adapter;
>> struct i2c_algo_bit_data bit;
>> };
>>
>
> There are few flavors of these drivers. In some of them
> the i2c_adapter for ddc is allocated and initialized by
> the driver, which must provide a place in memory to hold
> the adapter. ast is an example of this approach.
>
> But there are others, such as for example exynos_hdmi.c.
> It gets its ddc adapter with of_find_i2c_adapter_by_node()
> and merely stores a pointer to it, while not managing the
> memory needed to hold the i2c_adapter.
I see.
> Do you have any idea how to accommodate these various
> flavors of drivers in the scheme you propose?
Something like
struct drm_i2c_adapter {
struct i2c_adapter *adapter;
struct drm_connector *connector;
};
with adapter either being allocated dynamically or acquired via
of_find_i2c_adapter_by_node(); with separate init and finish functions
for each variant. But it looks like over-abstraction to me. Without
prototyping the idea, I cannot say if it's worth the effort.
For something more simple, maybe just have a function to attach an i2c
adapter to a connector:
drm_connector_attach_i2c_adapter(connector, i2c_adapter)
which sets the connector's ddc pointer and creates the sysfs entry if
the connector's entry is already present.
Best regards
Thomas
> Andrzej
>
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)
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Re: [PATCH v3 01/22] drm: Include ddc adapter pointer in struct drm_connector
Hi Thomas,
Thank you for your comments. Please see inline.
W dniu 30.06.2019 o 10:12, Thomas Zimmermann pisze:
Hi
I like the idea, but would prefer a more structured approach.
Setting connector->ddc before calling drm_sysfs_connector_add() seems
error prone. The dependency is not really clear from the code or interfaces.
The other thing is that drivers I mostly work on, ast and mgag200, have
code like this:
struct ast_i2c_chan {
struct i2c_adapter adapter;
struct drm_device *dev;
struct i2c_algo_bit_data bit;
};
struct ast_connector {
struct drm_connector base;
struct ast_i2c_chan *i2c;
};
It already encodes the connection between connector and ddc adapter.
I suggest to introduce struct drm_i2c_adapter
struct drm_i2c_adapter {
struct i2c_adapter base;
struct drm_connector *connector;
};
and convert drivers over to it. Ast would look like this:
struct ast_i2c_chan {
struct drm_i2c_adapter adapter;
struct i2c_algo_bit_data bit;
};
There are few flavors of these drivers. In some of them
the i2c_adapter for ddc is allocated and initialized by
the driver, which must provide a place in memory to hold
the adapter. ast is an example of this approach.
But there are others, such as for example exynos_hdmi.c.
It gets its ddc adapter with of_find_i2c_adapter_by_node()
and merely stores a pointer to it, while not managing the
memory needed to hold the i2c_adapter.
Do you have any idea how to accommodate these various
flavors of drivers in the scheme you propose?
Andrzej
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Re: [PATCH v3 01/22] drm: Include ddc adapter pointer in struct drm_connector
Hi
I like the idea, but would prefer a more structured approach.
Setting connector->ddc before calling drm_sysfs_connector_add() seems
error prone. The dependency is not really clear from the code or interfaces.
The other thing is that drivers I mostly work on, ast and mgag200, have
code like this:
struct ast_i2c_chan {
struct i2c_adapter adapter;
struct drm_device *dev;
struct i2c_algo_bit_data bit;
};
struct ast_connector {
struct drm_connector base;
struct ast_i2c_chan *i2c;
};
It already encodes the connection between connector and ddc adapter.
I suggest to introduce struct drm_i2c_adapter
struct drm_i2c_adapter {
struct i2c_adapter base;
struct drm_connector *connector;
};
and convert drivers over to it. Ast would look like this:
struct ast_i2c_chan {
struct drm_i2c_adapter adapter;
struct i2c_algo_bit_data bit;
};
Two new sysfs functions would set up and remove the file.
int drm_sysfs_i2c_adapter_add(struct drm_i2c_adapter *i2c);
void drm_sysfs_i2c_adapter_remove(struct drm_i2c_adapter *i2c);
The i2c adapter, connector->ddc pointer and sysfs entry would be
initialized by
drm_i2c_adapter_init(struct drm_i2c_adapter *i2c, struct connector
*connector, void *algo_data);
and cleaned up by
drm_i2c_adapter_remove(struct drm_i2c_adapter *i2c);
Thoughts?
Best regards
Thomas
Am 28.06.19 um 18:01 schrieb Andrzej Pietrasiewicz:
> Add generic code which creates symbolic links in sysfs, pointing to ddc
> interface used by a particular video output. For example:
>
> ls -l /sys/class/drm/card0-HDMI-A-1/ddc
> lrwxrwxrwx 1 root root 0 Jun 24 10:42 /sys/class/drm/card0-HDMI-A-1/ddc \
> -> ../../../../soc/1388.i2c/i2c-2
>
> This makes it easy for user to associate a display with its ddc adapter
> and use e.g. ddcutil to control the chosen monitor.
>
> This patch adds an i2c_adapter pointer to struct drm_connector. Particular
> drivers can then use it instead of using their own private instance. If a
> connector contains a ddc, then create a symbolic link in sysfs.
>
> Signed-off-by: Andrzej Pietrasiewicz
> Acked-by: Daniel Vetter
> ---
> drivers/gpu/drm/drm_sysfs.c | 7 +++
> include/drm/drm_connector.h | 11 +++
> 2 files changed, 18 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
> index ad10810bc972..26d359b39785 100644
> --- a/drivers/gpu/drm/drm_sysfs.c
> +++ b/drivers/gpu/drm/drm_sysfs.c
> @@ -294,6 +294,9 @@ int drm_sysfs_connector_add(struct drm_connector
> *connector)
> /* Let userspace know we have a new connector */
> drm_sysfs_hotplug_event(dev);
>
> + if (connector->ddc)
> + return sysfs_create_link(&connector->kdev->kobj,
> + &connector->ddc->dev.kobj, "ddc");
> return 0;
> }
>
> @@ -301,6 +304,10 @@ void drm_sysfs_connector_remove(struct drm_connector
> *connector)
> {
> if (!connector->kdev)
> return;
> +
> + if (connector->ddc)
> + sysfs_remove_link(&connector->kdev->kobj, "ddc");
> +
> DRM_DEBUG("removing \"%s\" from sysfs\n",
> connector->name);
>
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index ca745d9feaf5..1ad3d1d54ba7 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -23,6 +23,7 @@
> #ifndef __DRM_CONNECTOR_H__
> #define __DRM_CONNECTOR_H__
>
> +#include
> #include
> #include
> #include
> @@ -1308,6 +1309,16 @@ struct drm_connector {
>* [0]: progressive, [1]: interlaced
>*/
> int audio_latency[2];
> +
> + /**
> + * @ddc: associated ddc adapter.
> + * A connector usually has its associated ddc adapter. If a driver uses
> + * this field, then an appropriate symbolic link is created in connector
> + * sysfs directory to make it easy for the user to tell which i2c
> + * adapter is for a particular display.
> + */
> + struct i2c_adapter *ddc;
> +
> /**
>* @null_edid_counter: track sinks that give us all zeros for the EDID.
>* Needed to workaround some HW bugs where we get all 0s
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)
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[PATCH v3 01/22] drm: Include ddc adapter pointer in struct drm_connector
Add generic code which creates symbolic links in sysfs, pointing to ddc
interface used by a particular video output. For example:
ls -l /sys/class/drm/card0-HDMI-A-1/ddc
lrwxrwxrwx 1 root root 0 Jun 24 10:42 /sys/class/drm/card0-HDMI-A-1/ddc \
-> ../../../../soc/1388.i2c/i2c-2
This makes it easy for user to associate a display with its ddc adapter
and use e.g. ddcutil to control the chosen monitor.
This patch adds an i2c_adapter pointer to struct drm_connector. Particular
drivers can then use it instead of using their own private instance. If a
connector contains a ddc, then create a symbolic link in sysfs.
Signed-off-by: Andrzej Pietrasiewicz
Acked-by: Daniel Vetter
---
drivers/gpu/drm/drm_sysfs.c | 7 +++
include/drm/drm_connector.h | 11 +++
2 files changed, 18 insertions(+)
diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
index ad10810bc972..26d359b39785 100644
--- a/drivers/gpu/drm/drm_sysfs.c
+++ b/drivers/gpu/drm/drm_sysfs.c
@@ -294,6 +294,9 @@ int drm_sysfs_connector_add(struct drm_connector *connector)
/* Let userspace know we have a new connector */
drm_sysfs_hotplug_event(dev);
+ if (connector->ddc)
+ return sysfs_create_link(&connector->kdev->kobj,
+&connector->ddc->dev.kobj, "ddc");
return 0;
}
@@ -301,6 +304,10 @@ void drm_sysfs_connector_remove(struct drm_connector
*connector)
{
if (!connector->kdev)
return;
+
+ if (connector->ddc)
+ sysfs_remove_link(&connector->kdev->kobj, "ddc");
+
DRM_DEBUG("removing \"%s\" from sysfs\n",
connector->name);
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index ca745d9feaf5..1ad3d1d54ba7 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -23,6 +23,7 @@
#ifndef __DRM_CONNECTOR_H__
#define __DRM_CONNECTOR_H__
+#include
#include
#include
#include
@@ -1308,6 +1309,16 @@ struct drm_connector {
* [0]: progressive, [1]: interlaced
*/
int audio_latency[2];
+
+ /**
+* @ddc: associated ddc adapter.
+* A connector usually has its associated ddc adapter. If a driver uses
+* this field, then an appropriate symbolic link is created in connector
+* sysfs directory to make it easy for the user to tell which i2c
+* adapter is for a particular display.
+*/
+ struct i2c_adapter *ddc;
+
/**
* @null_edid_counter: track sinks that give us all zeros for the EDID.
* Needed to workaround some HW bugs where we get all 0s
--
2.17.1
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