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

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

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