Re: [RESEND RFC PATCH 2/5] firmware: sysfb: Add helpers to unregister a pdev and disable registration

On Wed, Apr 06, 2022 at 11:39:16PM +0200, Javier Martinez Canillas wrote:

These can be used by subsystems to unregister a platform device registered by sysfb and also to disable future platform device registration in sysfb.

Suggested-by: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Javier Martinez Canillas javierm@redhat.com

---

drivers/firmware/sysfb.c | 47 +++++++++++++++++++++++++++++++++++----- include/linux/sysfb.h | 19 ++++++++++++++++ 2 files changed, 60 insertions(+), 6 deletions(-)

diff --git a/drivers/firmware/sysfb.c b/drivers/firmware/sysfb.c index b032f40a92de..08ae78c083f1 100644 --- a/drivers/firmware/sysfb.c +++ b/drivers/firmware/sysfb.c @@ -34,21 +34,52 @@ #include <linux/screen_info.h> #include <linux/sysfb.h>

+static struct platform_device *pd; +static DEFINE_MUTEX(load_lock); +static bool disabled;

+void sysfb_disable(void) +{

• mutex_lock(&load_lock);
• disabled = true;
• mutex_unlock(&load_lock);

+} +EXPORT_SYMBOL_GPL(sysfb_disable);

+bool sysfb_try_unregister(struct device *dev) +{

• bool ret = true;
• mutex_lock(&load_lock);
• if (!pd || pd != to_platform_device(dev))

• return false;
  

• platform_device_unregister(to_platform_device(dev));
• pd = NULL;
• mutex_unlock(&load_lock);
• return ret;

+} +EXPORT_SYMBOL_GPL(sysfb_try_unregister);

Kerneldoc for these plus adding that to Documentation/firmware/other_interfaces.rst would be really neat.

With that added Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch

static __init int sysfb_init(void) { struct screen_info *si = &screen_info; struct simplefb_platform_data mode;

• struct platform_device *pd; const char *name; bool compatible;
• int ret;

• int ret = 0;

• mutex_lock(&load_lock);

• if (disabled)

• goto unlock_mutex;
  
  

  /* try to create a simple-framebuffer device */ compatible = sysfb_parse_mode(si, &mode); if (compatible) { pd = sysfb_create_simplefb(si, &mode); if (!IS_ERR(pd))

• 	return 0;
  

• 	goto unlock_mutex;
  

  }

  /* if the FB is incompatible, create a legacy framebuffer device */

@@ -60,8 +91,10 @@ static __init int sysfb_init(void) name = "platform-framebuffer";

pd = platform_device_alloc(name, 0);

• if (!pd)

• return -ENOMEM;
  

• if (!pd) {

• ret = -ENOMEM;
  

• goto unlock_mutex;
  

• }

  sysfb_apply_efi_quirks(pd);

@@ -73,9 +106,11 @@ static __init int sysfb_init(void) if (ret) goto err;

• return 0;

• goto unlock_mutex;

err: platform_device_put(pd); +unlock_mutex:

• mutex_unlock(&load_lock); return ret;

}

diff --git a/include/linux/sysfb.h b/include/linux/sysfb.h index 708152e9037b..e8c0313fac8f 100644 --- a/include/linux/sysfb.h +++ b/include/linux/sysfb.h @@ -55,6 +55,25 @@ struct efifb_dmi_info { int flags; };

+#ifdef CONFIG_SYSFB

+void sysfb_disable(void); +bool sysfb_try_unregister(struct device *dev);

+#else /* CONFIG_SYSFB */

+static inline void sysfb_disable(void) +{

+}

+static inline bool sysfb_try_unregister(struct device *dev) +{

• return false;

+}

+#endif /* CONFIG_SYSFB */

#ifdef CONFIG_EFI

extern struct efifb_dmi_info efifb_dmi_list[];

2.35.1