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

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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?

Thanks,
Matthieu

On Mon, Aug 8 2022 at 08:19:01 PM +0300, Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> wrote:
On Mon, 08 Aug 2022, Matthieu CHARETTE <matthieu.charette@xxxxxxxxx> 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@xxxxxxxxxxxxxxx> wrote:
 On Wed, 27 Jul 2022, Matthieu CHARETTE <matthieu.charette@xxxxxxxxx
 <mailto:matthieu.charette@xxxxxxxxx>> 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@xxxxxxxxx
 <mailto:matthieu.charette@xxxxxxxxx>>
  ---
   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





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