Re: [PATCH] drm: Fix EDID firmware load on resume

[Jani Nikula <jani.nikula@linux.intel.com>]

On Mon, 12 Sep 2022, Matthieu CHARETTE <matthieu.charette@gmail.com> wrote:
> Hi,
>
> Sorry for late reply.
>
> How do you propose to go then?
> Can we still use a persistent platform device to load the firmware and 
> cache it? But, in this case the system will still crash in case the 
> user change drm.edid_firmware then, without replugging the device, he 
> suspends and resumes the machine.
> Or you may have a better idea?

Maybe. Please try [1]. Could it be as simple as that?


BR,
Jani.


[1] https://patchwork.freedesktop.org/patch/msgid/20221006222146.2375217-1-jani.nikula@intel.com

>
> Thanks,
> Matthieu
>
> On Mon, Aug 8 2022 at 08:19:01 PM +0300, Jani Nikula 
> <jani.nikula@linux.intel.com> wrote:
>> On Mon, 08 Aug 2022, Matthieu CHARETTE <matthieu.charette@gmail.com> 
>> wrote:
>>>  Sorry, What do you mean?
>> 
>> You cache with one name at connector init time, but the name specified
>> using drm.edid_firmware may be changed whenever, to cause the next 
>> EDID
>> read to use a different EDID firmware.
>> 
>> BR,
>> Jani.
>> 
>> 
>>> 
>>>  Matthieu
>>> 
>>>  On Tue, Aug 2 2022 at 05:29:12 PM +0300, Jani Nikula
>>>  <jani.nikula@linux.intel.com> wrote:
>>>>  On Wed, 27 Jul 2022, Matthieu CHARETTE <matthieu.charette@gmail.com
>>>>  <mailto:matthieu.charette@gmail.com>> wrote:
>>>>>   Loading an EDID using drm.edid_firmware parameter makes resume to
>>>>>  fail
>>>>>   after firmware cache is being cleaned. This is because 
>>>>> edid_load()
>>>>>  use a
>>>>>   temporary device to request the firmware. This cause the EDID
>>>>>  firmware
>>>>>   not to be cached from suspend. And, requesting the EDID firmware
>>>>>  return
>>>>>   an error during resume.
>>>>>   So the request_firmware() call should use a permanent device for
>>>>>  each
>>>>>   connector. Also, we should cache the EDID even if no monitor is
>>>>>   connected, in case it's plugged while suspended.
>>>> 
>>>>  AFAICT this breaks changing drm.edid_firmware runtime.
>>>> 
>>>>  BR,
>>>>  Jani.
>>>> 
>>>>> 
>>>>>   Link: <https://gitlab.freedesktop.org/drm/amd/-/issues/2061>
>>>>>   Signed-off-by: Matthieu CHARETTE <matthieu.charette@gmail.com
>>>>>  <mailto:matthieu.charette@gmail.com>>
>>>>>   ---
>>>>>    drivers/gpu/drm/drm_connector.c |  9 ++++
>>>>>    drivers/gpu/drm/drm_edid_load.c | 81
>>>>>  ++++++++++++++++++++++++++++-----
>>>>>    include/drm/drm_connector.h     | 12 +++++
>>>>>    include/drm/drm_edid.h          |  3 ++
>>>>>    4 files changed, 94 insertions(+), 11 deletions(-)
>>>>> 
>>>>>   diff --git a/drivers/gpu/drm/drm_connector.c
>>>>>  b/drivers/gpu/drm/drm_connector.c
>>>>>   index 1c48d162c77e..e8819ebf1c4b 100644
>>>>>   --- a/drivers/gpu/drm/drm_connector.c
>>>>>   +++ b/drivers/gpu/drm/drm_connector.c
>>>>>   @@ -31,6 +31,7 @@
>>>>>    #include <drm/drm_privacy_screen_consumer.h>
>>>>>    #include <drm/drm_sysfs.h>
>>>>> 
>>>>>   +#include <linux/platform_device.h>
>>>>>    #include <linux/uaccess.h>
>>>>> 
>>>>>    #include "drm_crtc_internal.h"
>>>>>   @@ -289,6 +290,9 @@ int drm_connector_init(struct drm_device 
>>>>> *dev,
>>>>> 
>>>>>    	drm_connector_get_cmdline_mode(connector);
>>>>> 
>>>>>   +	connector->edid_load_pdev = NULL;
>>>>>   +	drm_cache_edid_firmware(connector);
>>>>>   +
>>>>>    	/* We should add connectors at the end to avoid upsetting the
>>>>>  connector
>>>>>    	 * index too much.
>>>>>    	 */
>>>>>   @@ -473,6 +477,11 @@ void drm_connector_cleanup(struct
>>>>>  drm_connector *connector)
>>>>>    		connector->tile_group = NULL;
>>>>>    	}
>>>>> 
>>>>>   +	if (connector->edid_load_pdev) {
>>>>>   +		platform_device_unregister(connector->edid_load_pdev);
>>>>>   +		connector->edid_load_pdev = NULL;
>>>>>   +	}
>>>>>   +
>>>>>    	list_for_each_entry_safe(mode, t, &connector->probed_modes, 
>>>>> head)
>>>>>    		drm_mode_remove(connector, mode);
>>>>> 
>>>>>   diff --git a/drivers/gpu/drm/drm_edid_load.c
>>>>>  b/drivers/gpu/drm/drm_edid_load.c
>>>>>   index 37d8ba3ddb46..5a82be9917ec 100644
>>>>>   --- a/drivers/gpu/drm/drm_edid_load.c
>>>>>   +++ b/drivers/gpu/drm/drm_edid_load.c
>>>>>   @@ -167,6 +167,19 @@ static int edid_size(const u8 *edid, int
>>>>>  data_size)
>>>>>    	return (edid[0x7e] + 1) * EDID_LENGTH;
>>>>>    }
>>>>> 
>>>>>   +static struct platform_device *edid_pdev(const char
>>>>>  *connector_name)
>>>>>   +{
>>>>>   +	struct platform_device *pdev =
>>>>>  platform_device_register_simple(connector_name, -1, NULL, 0);
>>>>>   +
>>>>>   +	if (IS_ERR(pdev)) {
>>>>>   +		DRM_ERROR("Failed to register EDID firmware platform device "
>>>>>   +			"for connector \"%s\"\n", connector_name);
>>>>>   +		return ERR_CAST(pdev);
>>>>>   +	}
>>>>>   +
>>>>>   +	return pdev;
>>>>>   +}
>>>>>   +
>>>>>    static void *edid_load(struct drm_connector *connector, const 
>>>>> char
>>>>>  *name,
>>>>>    			const char *connector_name)
>>>>>    {
>>>>>   @@ -182,18 +195,17 @@ static void *edid_load(struct drm_connector
>>>>>  *connector, const char *name,
>>>>>    		fwdata = generic_edid[builtin];
>>>>>    		fwsize = sizeof(generic_edid[builtin]);
>>>>>    	} else {
>>>>>   -		struct platform_device *pdev;
>>>>>   +		struct platform_device *pdev = connector->edid_load_pdev;
>>>>>    		int err;
>>>>> 
>>>>>   -		pdev = platform_device_register_simple(connector_name, -1, 
>>>>> NULL,
>>>>>  0);
>>>>>   -		if (IS_ERR(pdev)) {
>>>>>   -			DRM_ERROR("Failed to register EDID firmware platform device "
>>>>>   -				  "for connector \"%s\"\n", connector_name);
>>>>>   -			return ERR_CAST(pdev);
>>>>>   +		if (WARN_ON(!pdev)) {
>>>>>   +			pdev = edid_pdev(connector_name);
>>>>>   +			if (IS_ERR(pdev))
>>>>>   +				return ERR_CAST(pdev);
>>>>>   +			connector->edid_load_pdev = pdev;
>>>>>    		}
>>>>> 
>>>>>    		err = request_firmware(&fw, name, &pdev->dev);
>>>>>   -		platform_device_unregister(pdev);
>>>>>    		if (err) {
>>>>>    			DRM_ERROR("Requesting EDID firmware \"%s\" failed 
>>>>> (err=%d)\n",
>>>>>    				  name, err);
>>>>>   @@ -263,11 +275,9 @@ static void *edid_load(struct drm_connector
>>>>>  *connector, const char *name,
>>>>>    	return edid;
>>>>>    }
>>>>> 
>>>>>   -struct edid *drm_load_edid_firmware(struct drm_connector
>>>>>  *connector)
>>>>>   +static char *edid_name(const char *connector_name)
>>>>>    {
>>>>>   -	const char *connector_name = connector->name;
>>>>>    	char *edidname, *last, *colon, *fwstr, *edidstr, *fallback = 
>>>>> NULL;
>>>>>   -	struct edid *edid;
>>>>> 
>>>>>    	if (edid_firmware[0] == '\0')
>>>>>    		return ERR_PTR(-ENOENT);
>>>>>   @@ -310,8 +320,57 @@ struct edid *drm_load_edid_firmware(struct
>>>>>  drm_connector *connector)
>>>>>    	if (*last == '\n')
>>>>>    		*last = '\0';
>>>>> 
>>>>>   -	edid = edid_load(connector, edidname, connector_name);
>>>>>   +	edidname = kstrdup(edidname, GFP_KERNEL);
>>>>>   +	if (!edidname) {
>>>>>   +		kfree(fwstr);
>>>>>   +		return ERR_PTR(-ENOMEM);
>>>>>   +	}
>>>>>   +
>>>>>    	kfree(fwstr);
>>>>>   +	return edidname;
>>>>>   +}
>>>>>   +
>>>>>   +void drm_cache_edid_firmware(struct drm_connector *connector)
>>>>>   +{
>>>>>   +	const char *connector_name = connector->name;
>>>>>   +	const char *edidname = edid_name(connector_name);
>>>>>   +	struct platform_device *pdev;
>>>>>   +	int err;
>>>>>   +
>>>>>   +	if (IS_ERR(edidname))
>>>>>   +		return;
>>>>>   +
>>>>>   +	if (match_string(generic_edid_name, GENERIC_EDIDS, edidname) >=
>>>>>  0) {
>>>>>   +		kfree(edidname);
>>>>>   +		return;
>>>>>   +	}
>>>>>   +
>>>>>   +	pdev = edid_pdev(connector_name);
>>>>>   +	if (IS_ERR(pdev)) {
>>>>>   +		kfree(edidname);
>>>>>   +		return;
>>>>>   +	}
>>>>>   +	connector->edid_load_pdev = pdev;
>>>>>   +
>>>>>   +	err = firmware_request_cache(&pdev->dev, edidname);
>>>>>   +	if (err)
>>>>>   +		DRM_ERROR("Requesting EDID firmware cache \"%s\" failed
>>>>>  (err=%d)\n",
>>>>>   +			edidname, err);
>>>>>   +
>>>>>   +	kfree(edidname);
>>>>>   +}
>>>>>   +
>>>>>   +struct edid *drm_load_edid_firmware(struct drm_connector
>>>>>  *connector)
>>>>>   +{
>>>>>   +	const char *connector_name = connector->name;
>>>>>   +	const char *edidname = edid_name(connector_name);
>>>>>   +	struct edid *edid;
>>>>>   +
>>>>>   +	if (IS_ERR(edidname))
>>>>>   +		return ERR_CAST(edidname);
>>>>>   +
>>>>>   +	edid = edid_load(connector, edidname, connector_name);
>>>>>   +	kfree(edidname);
>>>>> 
>>>>>    	return edid;
>>>>>    }
>>>>>   diff --git a/include/drm/drm_connector.h
>>>>>  b/include/drm/drm_connector.h
>>>>>   index 3ac4bf87f257..47c84741517e 100644
>>>>>   --- a/include/drm/drm_connector.h
>>>>>   +++ b/include/drm/drm_connector.h
>>>>>   @@ -1573,6 +1573,18 @@ struct drm_connector {
>>>>>    	 */
>>>>>    	struct i2c_adapter *ddc;
>>>>> 
>>>>>   +	/**
>>>>>   +	 * @edid_load_pdev: Platform device for loading EDID via 
>>>>> firmware.
>>>>>   +	 *
>>>>>   +	 * The platform device is registered in drm_connector_init() in
>>>>>  case a
>>>>>   +	 * custom EDID firmware is used with `edid_firmware` parameter.
>>>>>  Otherwise,
>>>>>   +	 * it is set to NULL.
>>>>>   +	 *
>>>>>   +	 * Platform device is unregistered in drm_connector_cleanup() 
>>>>> if
>>>>>  it
>>>>>   +	 * is not NULL.
>>>>>   +	 */
>>>>>   +	struct platform_device *edid_load_pdev;
>>>>>   +
>>>>>    	/**
>>>>>    	 * @null_edid_counter: track sinks that give us all zeros for 
>>>>> the
>>>>>  EDID.
>>>>>    	 * Needed to workaround some HW bugs where we get all 0s
>>>>>   diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
>>>>>   index b2756753370b..e907c928a35d 100644
>>>>>   --- a/include/drm/drm_edid.h
>>>>>   +++ b/include/drm/drm_edid.h
>>>>>   @@ -378,10 +378,13 @@ int drm_av_sync_delay(struct drm_connector
>>>>>  *connector,
>>>>>    		      const struct drm_display_mode *mode);
>>>>> 
>>>>>    #ifdef CONFIG_DRM_LOAD_EDID_FIRMWARE
>>>>>   +void drm_cache_edid_firmware(struct drm_connector *connector);
>>>>>    struct edid *drm_load_edid_firmware(struct drm_connector
>>>>>  *connector);
>>>>>    int __drm_set_edid_firmware_path(const char *path);
>>>>>    int __drm_get_edid_firmware_path(char *buf, size_t bufsize);
>>>>>    #else
>>>>>   +inline void
>>>>>   +drm_cache_edid_firmware(struct drm_connector *connector);
>>>>>    static inline struct edid *
>>>>>    drm_load_edid_firmware(struct drm_connector *connector)
>>>>>    {
>>>> 
>>>>  --
>>>>  Jani Nikula, Intel Open Source Graphics Center
>>> 
>> 
>> --
>> Jani Nikula, Intel Open Source Graphics Center
>
>

-- 
Jani Nikula, Intel Open Source Graphics Center