[v3,2/5] drm: Add drm_get_acpi_edid() helper

  Some manufacturers have intentionally put an EDID that differs from
the EDID on the internal panel on laptops.  Drivers can call this
helper to attempt to fetch the EDID from the BIOS's ACPI _DDC method.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
v1->v2:
 * Split code from previous amdgpu specific helper to generic drm helper.
v2->v3:
 * Add an extra select to fix a variety of randconfig errors found from
   LKP robot.
---
 drivers/gpu/drm/Kconfig    |  5 +++
 drivers/gpu/drm/drm_edid.c | 73 ++++++++++++++++++++++++++++++++++++++
 include/drm/drm_edid.h     |  1 +
 3 files changed, 79 insertions(+)
  

On 2/2/2024 3:41 AM, Mario Limonciello wrote:
> Some manufacturers have intentionally put an EDID that differs from
> the EDID on the internal panel on laptops.  Drivers can call this
> helper to attempt to fetch the EDID from the BIOS's ACPI _DDC method.
>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
> v1->v2:
>   * Split code from previous amdgpu specific helper to generic drm helper.
> v2->v3:
>   * Add an extra select to fix a variety of randconfig errors found from
>     LKP robot.
> ---
>   drivers/gpu/drm/Kconfig    |  5 +++
>   drivers/gpu/drm/drm_edid.c | 73 ++++++++++++++++++++++++++++++++++++++
>   include/drm/drm_edid.h     |  1 +
>   3 files changed, 79 insertions(+)
>
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 2520db0b776e..14df907c96c8 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -21,6 +21,11 @@ menuconfig DRM
>   	select KCMP
>   	select VIDEO_CMDLINE
>   	select VIDEO_NOMODESET
> +	select ACPI_VIDEO if ACPI
> +	select BACKLIGHT_CLASS_DEVICE if ACPI
> +	select INPUT if ACPI
> +	select X86_PLATFORM_DEVICES if ACPI && X86
> +	select ACPI_WMI if ACPI && X86
>   	help
>   	  Kernel-level support for the Direct Rendering Infrastructure (DRI)
>   	  introduced in XFree86 4.0. If you say Y here, you need to select
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 69c68804023f..1fbbeaa664b2 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -28,6 +28,7 @@
>    * DEALINGS IN THE SOFTWARE.
>    */
>   
> +#include <acpi/video.h>
>   #include <linux/bitfield.h>
>   #include <linux/cec.h>
>   #include <linux/hdmi.h>
> @@ -2188,6 +2189,47 @@ drm_do_probe_ddc_edid(void *data, u8 *buf, unsigned int block, size_t len)
>   	return ret == xfers ? 0 : -1;
>   }
>   
> +/**
> + * drm_do_probe_acpi_edid() - get EDID information via ACPI _DDC
> + * @data: struct drm_device
> + * @buf: EDID data buffer to be filled
> + * @block: 128 byte EDID block to start fetching from
> + * @len: EDID data buffer length to fetch
> + *
> + * Try to fetch EDID information by calling acpi_video_get_edid() function.
> + *
> + * Return: 0 on success or error code on failure.
> + */
> +static int
> +drm_do_probe_acpi_edid(void *data, u8 *buf, unsigned int block, size_t len)
> +{
> +	struct drm_device *ddev = data;
> +	struct acpi_device *acpidev = ACPI_COMPANION(ddev->dev);
> +	unsigned char start = block * EDID_LENGTH;
> +	void *edid;
> +	int r;
> +
> +	if (!acpidev)
> +		return -ENODEV;
> +
> +	/* fetch the entire edid from BIOS */
> +	r = acpi_video_get_edid(acpidev, ACPI_VIDEO_DISPLAY_LCD, -1, &edid);
> +	if (r < 0) {
> +		DRM_DEBUG_KMS("Failed to get EDID from ACPI: %d\n", r);
> +		return -EINVAL;
> +	}
> +	if (len > r || start > r || start + len > r) {
> +		r = EINVAL;
-EINVAL ?
> +		goto cleanup;
> +	}
> +
> +	memcpy(buf, edid + start, len);
> +	r = 0;
New line before goto label?
> +cleanup:
> +	kfree(edid);
> +	return r;
> +}
> +
>   static void connector_bad_edid(struct drm_connector *connector,
>   			       const struct edid *edid, int num_blocks)
>   {
> @@ -2643,6 +2685,37 @@ struct edid *drm_get_edid(struct drm_connector *connector,
>   }
>   EXPORT_SYMBOL(drm_get_edid);
>   
> +/**
> + * drm_get_acpi_edid - get EDID data, if available
> + * @connector: connector we're probing
> + *
> + * Use the BIOS to attempt to grab EDID data if possible.  If found,
> + * attach it to the connector.
> + *
> + * Return: Pointer to valid EDID or NULL if we couldn't find any.
> + */
> +struct edid *drm_get_acpi_edid(struct drm_connector *connector)
> +{
> +	struct edid *edid = NULL;
> +
> +	switch (connector->connector_type) {
> +	case DRM_MODE_CONNECTOR_LVDS:
> +	case DRM_MODE_CONNECTOR_eDP:
> +		break;
> +	default:
> +		return NULL;
> +	}
> +
> +	if (connector->force == DRM_FORCE_OFF)
> +		return NULL;
> +
> +	edid = _drm_do_get_edid(connector, drm_do_probe_acpi_edid, connector->dev, NULL);
> +
> +	drm_connector_update_edid_property(connector, edid);
> +	return edid;
> +}
> +EXPORT_SYMBOL(drm_get_acpi_edid);
> +
>   /**
>    * drm_edid_read_custom - Read EDID data using given EDID block read function
>    * @connector: Connector to use
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index 518d1b8106c7..60fbdc06badc 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -412,6 +412,7 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
>   	void *data);
>   struct edid *drm_get_edid(struct drm_connector *connector,
>   			  struct i2c_adapter *adapter);
> +struct edid *drm_get_acpi_edid(struct drm_connector *connector);
>   u32 drm_edid_get_panel_id(struct i2c_adapter *adapter);
>   struct edid *drm_get_edid_switcheroo(struct drm_connector *connector,
>   				     struct i2c_adapter *adapter);

New line before return ?
  

On Thu, 01 Feb 2024, Mario Limonciello <mario.limonciello@amd.com> wrote:
> Some manufacturers have intentionally put an EDID that differs from
> the EDID on the internal panel on laptops.  Drivers can call this
> helper to attempt to fetch the EDID from the BIOS's ACPI _DDC method.

I'm really not happy about adding new struct edid based APIs to
drm_edid.[ch]. Everything new should be struct drm_edid based. All
drivers should be converting towards struct drm_edid, instead of adding
more legacy to rip out later.

BR,
Jani.

>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
> v1->v2:
>  * Split code from previous amdgpu specific helper to generic drm helper.
> v2->v3:
>  * Add an extra select to fix a variety of randconfig errors found from
>    LKP robot.
> ---
>  drivers/gpu/drm/Kconfig    |  5 +++
>  drivers/gpu/drm/drm_edid.c | 73 ++++++++++++++++++++++++++++++++++++++
>  include/drm/drm_edid.h     |  1 +
>  3 files changed, 79 insertions(+)
>
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 2520db0b776e..14df907c96c8 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -21,6 +21,11 @@ menuconfig DRM
>  	select KCMP
>  	select VIDEO_CMDLINE
>  	select VIDEO_NOMODESET
> +	select ACPI_VIDEO if ACPI
> +	select BACKLIGHT_CLASS_DEVICE if ACPI
> +	select INPUT if ACPI
> +	select X86_PLATFORM_DEVICES if ACPI && X86
> +	select ACPI_WMI if ACPI && X86
>  	help
>  	  Kernel-level support for the Direct Rendering Infrastructure (DRI)
>  	  introduced in XFree86 4.0. If you say Y here, you need to select
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 69c68804023f..1fbbeaa664b2 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -28,6 +28,7 @@
>   * DEALINGS IN THE SOFTWARE.
>   */
>  
> +#include <acpi/video.h>
>  #include <linux/bitfield.h>
>  #include <linux/cec.h>
>  #include <linux/hdmi.h>
> @@ -2188,6 +2189,47 @@ drm_do_probe_ddc_edid(void *data, u8 *buf, unsigned int block, size_t len)
>  	return ret == xfers ? 0 : -1;
>  }
>  
> +/**
> + * drm_do_probe_acpi_edid() - get EDID information via ACPI _DDC
> + * @data: struct drm_device
> + * @buf: EDID data buffer to be filled
> + * @block: 128 byte EDID block to start fetching from
> + * @len: EDID data buffer length to fetch
> + *
> + * Try to fetch EDID information by calling acpi_video_get_edid() function.
> + *
> + * Return: 0 on success or error code on failure.
> + */
> +static int
> +drm_do_probe_acpi_edid(void *data, u8 *buf, unsigned int block, size_t len)
> +{
> +	struct drm_device *ddev = data;
> +	struct acpi_device *acpidev = ACPI_COMPANION(ddev->dev);
> +	unsigned char start = block * EDID_LENGTH;
> +	void *edid;
> +	int r;
> +
> +	if (!acpidev)
> +		return -ENODEV;
> +
> +	/* fetch the entire edid from BIOS */
> +	r = acpi_video_get_edid(acpidev, ACPI_VIDEO_DISPLAY_LCD, -1, &edid);
> +	if (r < 0) {
> +		DRM_DEBUG_KMS("Failed to get EDID from ACPI: %d\n", r);
> +		return -EINVAL;
> +	}
> +	if (len > r || start > r || start + len > r) {
> +		r = EINVAL;
> +		goto cleanup;
> +	}
> +
> +	memcpy(buf, edid + start, len);
> +	r = 0;
> +cleanup:
> +	kfree(edid);
> +	return r;
> +}
> +
>  static void connector_bad_edid(struct drm_connector *connector,
>  			       const struct edid *edid, int num_blocks)
>  {
> @@ -2643,6 +2685,37 @@ struct edid *drm_get_edid(struct drm_connector *connector,
>  }
>  EXPORT_SYMBOL(drm_get_edid);
>  
> +/**
> + * drm_get_acpi_edid - get EDID data, if available
> + * @connector: connector we're probing
> + *
> + * Use the BIOS to attempt to grab EDID data if possible.  If found,
> + * attach it to the connector.
> + *
> + * Return: Pointer to valid EDID or NULL if we couldn't find any.
> + */
> +struct edid *drm_get_acpi_edid(struct drm_connector *connector)
> +{
> +	struct edid *edid = NULL;
> +
> +	switch (connector->connector_type) {
> +	case DRM_MODE_CONNECTOR_LVDS:
> +	case DRM_MODE_CONNECTOR_eDP:
> +		break;
> +	default:
> +		return NULL;
> +	}
> +
> +	if (connector->force == DRM_FORCE_OFF)
> +		return NULL;
> +
> +	edid = _drm_do_get_edid(connector, drm_do_probe_acpi_edid, connector->dev, NULL);
> +
> +	drm_connector_update_edid_property(connector, edid);
> +	return edid;
> +}
> +EXPORT_SYMBOL(drm_get_acpi_edid);
> +
>  /**
>   * drm_edid_read_custom - Read EDID data using given EDID block read function
>   * @connector: Connector to use
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index 518d1b8106c7..60fbdc06badc 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -412,6 +412,7 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
>  	void *data);
>  struct edid *drm_get_edid(struct drm_connector *connector,
>  			  struct i2c_adapter *adapter);
> +struct edid *drm_get_acpi_edid(struct drm_connector *connector);
>  u32 drm_edid_get_panel_id(struct i2c_adapter *adapter);
>  struct edid *drm_get_edid_switcheroo(struct drm_connector *connector,
>  				     struct i2c_adapter *adapter);
  

On 2/2/2024 04:29, Jani Nikula wrote:
> On Thu, 01 Feb 2024, Mario Limonciello <mario.limonciello@amd.com> wrote:
>> Some manufacturers have intentionally put an EDID that differs from
>> the EDID on the internal panel on laptops.  Drivers can call this
>> helper to attempt to fetch the EDID from the BIOS's ACPI _DDC method.
> 
> I'm really not happy about adding new struct edid based APIs to
> drm_edid.[ch]. Everything new should be struct drm_edid based. All
> drivers should be converting towards struct drm_edid, instead of adding
> more legacy to rip out later.

OK; I'll redo it with struct drm_edid.

The changeover for amdgpu to use drm_edid is going to be a pretty 
involved effort so I'm going to use a get_raw in amdgpu for now so we 
can unblock the issue this is fixing and let that part get removed when 
the rest of the overhaul gets done there.

> 
> BR,
> Jani.
> 
>>
>> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
>> ---
>> v1->v2:
>>   * Split code from previous amdgpu specific helper to generic drm helper.
>> v2->v3:
>>   * Add an extra select to fix a variety of randconfig errors found from
>>     LKP robot.
>> ---
>>   drivers/gpu/drm/Kconfig    |  5 +++
>>   drivers/gpu/drm/drm_edid.c | 73 ++++++++++++++++++++++++++++++++++++++
>>   include/drm/drm_edid.h     |  1 +
>>   3 files changed, 79 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>> index 2520db0b776e..14df907c96c8 100644
>> --- a/drivers/gpu/drm/Kconfig
>> +++ b/drivers/gpu/drm/Kconfig
>> @@ -21,6 +21,11 @@ menuconfig DRM
>>   	select KCMP
>>   	select VIDEO_CMDLINE
>>   	select VIDEO_NOMODESET
>> +	select ACPI_VIDEO if ACPI
>> +	select BACKLIGHT_CLASS_DEVICE if ACPI
>> +	select INPUT if ACPI
>> +	select X86_PLATFORM_DEVICES if ACPI && X86
>> +	select ACPI_WMI if ACPI && X86
>>   	help
>>   	  Kernel-level support for the Direct Rendering Infrastructure (DRI)
>>   	  introduced in XFree86 4.0. If you say Y here, you need to select
>> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
>> index 69c68804023f..1fbbeaa664b2 100644
>> --- a/drivers/gpu/drm/drm_edid.c
>> +++ b/drivers/gpu/drm/drm_edid.c
>> @@ -28,6 +28,7 @@
>>    * DEALINGS IN THE SOFTWARE.
>>    */
>>   
>> +#include <acpi/video.h>
>>   #include <linux/bitfield.h>
>>   #include <linux/cec.h>
>>   #include <linux/hdmi.h>
>> @@ -2188,6 +2189,47 @@ drm_do_probe_ddc_edid(void *data, u8 *buf, unsigned int block, size_t len)
>>   	return ret == xfers ? 0 : -1;
>>   }
>>   
>> +/**
>> + * drm_do_probe_acpi_edid() - get EDID information via ACPI _DDC
>> + * @data: struct drm_device
>> + * @buf: EDID data buffer to be filled
>> + * @block: 128 byte EDID block to start fetching from
>> + * @len: EDID data buffer length to fetch
>> + *
>> + * Try to fetch EDID information by calling acpi_video_get_edid() function.
>> + *
>> + * Return: 0 on success or error code on failure.
>> + */
>> +static int
>> +drm_do_probe_acpi_edid(void *data, u8 *buf, unsigned int block, size_t len)
>> +{
>> +	struct drm_device *ddev = data;
>> +	struct acpi_device *acpidev = ACPI_COMPANION(ddev->dev);
>> +	unsigned char start = block * EDID_LENGTH;
>> +	void *edid;
>> +	int r;
>> +
>> +	if (!acpidev)
>> +		return -ENODEV;
>> +
>> +	/* fetch the entire edid from BIOS */
>> +	r = acpi_video_get_edid(acpidev, ACPI_VIDEO_DISPLAY_LCD, -1, &edid);
>> +	if (r < 0) {
>> +		DRM_DEBUG_KMS("Failed to get EDID from ACPI: %d\n", r);
>> +		return -EINVAL;
>> +	}
>> +	if (len > r || start > r || start + len > r) {
>> +		r = EINVAL;
>> +		goto cleanup;
>> +	}
>> +
>> +	memcpy(buf, edid + start, len);
>> +	r = 0;
>> +cleanup:
>> +	kfree(edid);
>> +	return r;
>> +}
>> +
>>   static void connector_bad_edid(struct drm_connector *connector,
>>   			       const struct edid *edid, int num_blocks)
>>   {
>> @@ -2643,6 +2685,37 @@ struct edid *drm_get_edid(struct drm_connector *connector,
>>   }
>>   EXPORT_SYMBOL(drm_get_edid);
>>   
>> +/**
>> + * drm_get_acpi_edid - get EDID data, if available
>> + * @connector: connector we're probing
>> + *
>> + * Use the BIOS to attempt to grab EDID data if possible.  If found,
>> + * attach it to the connector.
>> + *
>> + * Return: Pointer to valid EDID or NULL if we couldn't find any.
>> + */
>> +struct edid *drm_get_acpi_edid(struct drm_connector *connector)
>> +{
>> +	struct edid *edid = NULL;
>> +
>> +	switch (connector->connector_type) {
>> +	case DRM_MODE_CONNECTOR_LVDS:
>> +	case DRM_MODE_CONNECTOR_eDP:
>> +		break;
>> +	default:
>> +		return NULL;
>> +	}
>> +
>> +	if (connector->force == DRM_FORCE_OFF)
>> +		return NULL;
>> +
>> +	edid = _drm_do_get_edid(connector, drm_do_probe_acpi_edid, connector->dev, NULL);
>> +
>> +	drm_connector_update_edid_property(connector, edid);
>> +	return edid;
>> +}
>> +EXPORT_SYMBOL(drm_get_acpi_edid);
>> +
>>   /**
>>    * drm_edid_read_custom - Read EDID data using given EDID block read function
>>    * @connector: Connector to use
>> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
>> index 518d1b8106c7..60fbdc06badc 100644
>> --- a/include/drm/drm_edid.h
>> +++ b/include/drm/drm_edid.h
>> @@ -412,6 +412,7 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
>>   	void *data);
>>   struct edid *drm_get_edid(struct drm_connector *connector,
>>   			  struct i2c_adapter *adapter);
>> +struct edid *drm_get_acpi_edid(struct drm_connector *connector);
>>   u32 drm_edid_get_panel_id(struct i2c_adapter *adapter);
>>   struct edid *drm_get_edid_switcheroo(struct drm_connector *connector,
>>   				     struct i2c_adapter *adapter);
>