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Date:   Mon, 08 Aug 2022 17:17:48 +0200
From:   Matthieu CHARETTE <matthieu.charette@gmail.com>
Subject: Re: [PATCH] drm: Fix EDID firmware load on resume
To:     Jani Nikula <jani.nikula@linux.intel.com>
Cc:     lkp@intel.com, kbuild-all@lists.01.org, tzimmermann@suse.de,
        airlied@linux.ie, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org, andrealmeid@igalia.com
Message-Id: <OHYAGR.5V9CNVUP533V3@gmail.com>
In-Reply-To: <87wnbqen2f.fsf@intel.com>
References: <202207172035.mtErdlaw-lkp@intel.com>
        <20220727074152.43059-1-matthieu.charette@gmail.com>
        <87wnbqen2f.fsf@intel.com>
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Sorry, What do you mean?

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> 
> 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>
>>  ---
>>   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