From nobody Fri Jun 19 07:16:41 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 13458C433EF for ; Wed, 6 Apr 2022 21:49:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230357AbiDFVvv (ORCPT ); Wed, 6 Apr 2022 17:51:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42484 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236361AbiDFVvK (ORCPT ); Wed, 6 Apr 2022 17:51:10 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id A07938BE35 for ; Wed, 6 Apr 2022 14:40:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1649281253; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kOqy/c/KjwvNtJK/R+j/LJQnwi5pZIwF5UUMed5h1E8=; b=Fvt2Dtx58ayDJSx2vV4rBrnRyyAwmIUxr318YXkNTd0dlNb7eETl23HA38FlcYD51/UdzP /WdOaJCE5JHvredWD6s5uCb3jeuzFbhVW+nDbpB7laqfw6MK651UlKBe4NhGFIlXoFFR8K QaeAWcZl1wItEf5ea0AzjHjuF/UYDlk= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-107-pNH_cdbRNmKFKWZQbS6gYw-1; Wed, 06 Apr 2022 17:40:52 -0400 X-MC-Unique: pNH_cdbRNmKFKWZQbS6gYw-1 Received: by mail-wr1-f69.google.com with SMTP id t15-20020adfdc0f000000b001ef93643476so814147wri.2 for ; Wed, 06 Apr 2022 14:40:52 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=kOqy/c/KjwvNtJK/R+j/LJQnwi5pZIwF5UUMed5h1E8=; b=wwLk/xswFqssW0L5ws8xz3QgvMEW5qIkBFh+GFRu1icEHDF3ydrePBkCkqTcv8d01K E4qyXLGAV0eBKQpkhUEPPWTaZ3bWS0OiZDrs6TQhLbdSTZT5Dv7mS7dpFzqVIeuz9pzS 8LgP8LooGOZe8OgPgnOPT4W9XYTjGifvj07/L22SRxNUcs29U2Dl9aI/0AirQP0FWTHR 19FMk3EFHjPmxtlEZhYRHHx7FKxj9PetAa4PGjZKf6XmF6PiOJoCjdTCOhV0KxI/ORl8 TJlRikPbrqjQvWZCsy4u9SSUs2gzavQN6ADKbdJo2BjY5RRy6XpwLIFZoSF/F36SWpy7 pVlQ== X-Gm-Message-State: AOAM532A28QOXJNS83pQDCCRIJvlHrDMeJrEHFZE1ncTM046R6Q/k292 HCf62BfT0JVTcGf0B83ToNRjhCWFweOIUQYT8obihdM8xJ3foqAvay1WB7aklHDE/LyFE6yLZw6 /nuhzmPcpu9bEBRwvfvYt5OTw9QeeI/SolfK3nD3p2lzL3neO6LKDD2kkkZgTJMYsN8G9FQTDun M= X-Received: by 2002:a7b:c0c9:0:b0:38e:7d65:6e7f with SMTP id s9-20020a7bc0c9000000b0038e7d656e7fmr9054406wmh.168.1649281251353; Wed, 06 Apr 2022 14:40:51 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzEvASRFqmeBI/gkKWoj3wck9xOJpn6025gTkIMDUq07B7B+SD3YIdjghFypSAm6QQAtr+Rbw== X-Received: by 2002:a7b:c0c9:0:b0:38e:7d65:6e7f with SMTP id s9-20020a7bc0c9000000b0038e7d656e7fmr9054390wmh.168.1649281251134; Wed, 06 Apr 2022 14:40:51 -0700 (PDT) Received: from minerva.home ([92.176.231.205]) by smtp.gmail.com with ESMTPSA id o29-20020a05600c511d00b0038e3532b23csm5876020wms.15.2022.04.06.14.40.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Apr 2022 14:40:50 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Cc: dri-devel@lists.freedesktop.org, Thomas Zimmermann , Daniel Vetter , Javier Martinez Canillas , Borislav Petkov , Greg Kroah-Hartman , Miaoqian Lin Subject: [RESEND RFC PATCH 1/5] firmware: sysfb: Make sysfb_create_simplefb() return a pdev pointer Date: Wed, 6 Apr 2022 23:39:15 +0200 Message-Id: <20220406213919.600294-2-javierm@redhat.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220406213919.600294-1-javierm@redhat.com> References: <20220406213919.600294-1-javierm@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" This function just returned 0 on success or an errno code on error, but it could be useful to sysfb_init() to get a pointer to the device registered. Signed-off-by: Javier Martinez Canillas --- drivers/firmware/sysfb.c | 4 ++-- drivers/firmware/sysfb_simplefb.c | 24 +++++++++++++++--------- include/linux/sysfb.h | 10 +++++----- 3 files changed, 22 insertions(+), 16 deletions(-) diff --git a/drivers/firmware/sysfb.c b/drivers/firmware/sysfb.c index 2bfbb05f7d89..b032f40a92de 100644 --- a/drivers/firmware/sysfb.c +++ b/drivers/firmware/sysfb.c @@ -46,8 +46,8 @@ static __init int sysfb_init(void) /* try to create a simple-framebuffer device */ compatible =3D sysfb_parse_mode(si, &mode); if (compatible) { - ret =3D sysfb_create_simplefb(si, &mode); - if (!ret) + pd =3D sysfb_create_simplefb(si, &mode); + if (!IS_ERR(pd)) return 0; } =20 diff --git a/drivers/firmware/sysfb_simplefb.c b/drivers/firmware/sysfb_sim= plefb.c index 76c4abc42a30..c42648ed3aad 100644 --- a/drivers/firmware/sysfb_simplefb.c +++ b/drivers/firmware/sysfb_simplefb.c @@ -57,8 +57,8 @@ __init bool sysfb_parse_mode(const struct screen_info *si, return false; } =20 -__init int sysfb_create_simplefb(const struct screen_info *si, - const struct simplefb_platform_data *mode) +__init struct platform_device *sysfb_create_simplefb(const struct screen_i= nfo *si, + const struct simplefb_platform_data *mode) { struct platform_device *pd; struct resource res; @@ -76,7 +76,7 @@ __init int sysfb_create_simplefb(const struct screen_info= *si, base |=3D (u64)si->ext_lfb_base << 32; if (!base || (u64)(resource_size_t)base !=3D base) { printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n"); - return -EINVAL; + return ERR_PTR(-EINVAL); } =20 /* @@ -93,7 +93,7 @@ __init int sysfb_create_simplefb(const struct screen_info= *si, length =3D mode->height * mode->stride; if (length > size) { printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n"); - return -EINVAL; + return ERR_PTR(-EINVAL); } length =3D PAGE_ALIGN(length); =20 @@ -104,25 +104,31 @@ __init int sysfb_create_simplefb(const struct screen_= info *si, res.start =3D base; res.end =3D res.start + length - 1; if (res.end <=3D res.start) - return -EINVAL; + return ERR_PTR(-EINVAL); =20 pd =3D platform_device_alloc("simple-framebuffer", 0); if (!pd) - return -ENOMEM; + return ERR_PTR(-ENOMEM); =20 sysfb_apply_efi_quirks(pd); =20 ret =3D platform_device_add_resources(pd, &res, 1); if (ret) { platform_device_put(pd); - return ret; + return ERR_PTR(ret); } =20 ret =3D platform_device_add_data(pd, mode, sizeof(*mode)); if (ret) { platform_device_put(pd); - return ret; + return ERR_PTR(ret); } =20 - return platform_device_add(pd); + ret =3D platform_device_add(pd); + if (ret) { + platform_device_put(pd); + return ERR_PTR(ret); + } + + return pd; } diff --git a/include/linux/sysfb.h b/include/linux/sysfb.h index b0dcfa26d07b..708152e9037b 100644 --- a/include/linux/sysfb.h +++ b/include/linux/sysfb.h @@ -72,8 +72,8 @@ static inline void sysfb_apply_efi_quirks(struct platform= _device *pd) =20 bool sysfb_parse_mode(const struct screen_info *si, struct simplefb_platform_data *mode); -int sysfb_create_simplefb(const struct screen_info *si, - const struct simplefb_platform_data *mode); +struct platform_device *sysfb_create_simplefb(const struct screen_info *si, + const struct simplefb_platform_data *mode); =20 #else /* CONFIG_SYSFB_SIMPLE */ =20 @@ -83,10 +83,10 @@ static inline bool sysfb_parse_mode(const struct screen= _info *si, return false; } =20 -static inline int sysfb_create_simplefb(const struct screen_info *si, - const struct simplefb_platform_data *mode) +static inline struct platform_device *sysfb_create_simplefb(const struct s= creen_info *si, + const struct simplefb_platform_data *mode) { - return -EINVAL; + return ERR_PTR(-EINVAL); } =20 #endif /* CONFIG_SYSFB_SIMPLE */ --=20 2.35.1 From nobody Fri Jun 19 07:16:41 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 214D8C433EF for ; Wed, 6 Apr 2022 21:50:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236387AbiDFVwM (ORCPT ); Wed, 6 Apr 2022 17:52:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41614 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236354AbiDFVvK (ORCPT ); Wed, 6 Apr 2022 17:51:10 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 6663A8BF4D for ; 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Wed, 06 Apr 2022 14:40:52 -0700 (PDT) Received: from minerva.home ([92.176.231.205]) by smtp.gmail.com with ESMTPSA id o29-20020a05600c511d00b0038e3532b23csm5876020wms.15.2022.04.06.14.40.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Apr 2022 14:40:51 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Cc: dri-devel@lists.freedesktop.org, Thomas Zimmermann , Daniel Vetter , Javier Martinez Canillas , Borislav Petkov , Greg Kroah-Hartman Subject: [RESEND RFC PATCH 2/5] firmware: sysfb: Add helpers to unregister a pdev and disable registration Date: Wed, 6 Apr 2022 23:39:16 +0200 Message-Id: <20220406213919.600294-3-javierm@redhat.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220406213919.600294-1-javierm@redhat.com> References: <20220406213919.600294-1-javierm@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 Signed-off-by: Javier Martinez Canillas --- 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 #include =20 +static struct platform_device *pd; +static DEFINE_MUTEX(load_lock); +static bool disabled; + +void sysfb_disable(void) +{ + mutex_lock(&load_lock); + disabled =3D true; + mutex_unlock(&load_lock); +} +EXPORT_SYMBOL_GPL(sysfb_disable); + +bool sysfb_try_unregister(struct device *dev) +{ + bool ret =3D true; + + mutex_lock(&load_lock); + if (!pd || pd !=3D to_platform_device(dev)) + return false; + + platform_device_unregister(to_platform_device(dev)); + pd =3D NULL; + mutex_unlock(&load_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(sysfb_try_unregister); + static __init int sysfb_init(void) { struct screen_info *si =3D &screen_info; struct simplefb_platform_data mode; - struct platform_device *pd; const char *name; bool compatible; - int ret; + int ret =3D 0; + + mutex_lock(&load_lock); + if (disabled) + goto unlock_mutex; =20 /* try to create a simple-framebuffer device */ compatible =3D sysfb_parse_mode(si, &mode); if (compatible) { pd =3D sysfb_create_simplefb(si, &mode); if (!IS_ERR(pd)) - return 0; + goto unlock_mutex; } =20 /* if the FB is incompatible, create a legacy framebuffer device */ @@ -60,8 +91,10 @@ static __init int sysfb_init(void) name =3D "platform-framebuffer"; =20 pd =3D platform_device_alloc(name, 0); - if (!pd) - return -ENOMEM; + if (!pd) { + ret =3D -ENOMEM; + goto unlock_mutex; + } =20 sysfb_apply_efi_quirks(pd); =20 @@ -73,9 +106,11 @@ static __init int sysfb_init(void) if (ret) goto err; =20 - return 0; + goto unlock_mutex; err: platform_device_put(pd); +unlock_mutex: + mutex_unlock(&load_lock); return ret; } =20 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; }; =20 +#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 =20 extern struct efifb_dmi_info efifb_dmi_list[]; --=20 2.35.1 From nobody Fri Jun 19 07:16:41 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA03DC433FE for ; Wed, 6 Apr 2022 21:49:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234849AbiDFVvq (ORCPT ); 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charset="utf-8" Drivers that want to remove registered conflicting framebuffers prior to register their own framebuffer, calls remove_conflicting_framebuffers(). This function takes the registration_lock mutex, to prevent a races when drivers register framebuffer devices. But if a conflicting framebuffer device is found, the underlaying platform device is unregistered and this will lead to the platform driver .remove callback to be called, which in turn will call to the unregister_framebuffer() that takes the same lock. To prevent this, a struct fb_info.forced_out field was used as indication to unregister_framebuffer() whether the mutex has to be grabbed or not. A cleaner solution is to drop the lock before platform_device_unregister() so unregister_framebuffer() can take it when called from the fbdev driver, and just grab the lock again after the device has been registered and do a removal loop restart. Since the framebuffer devices will already be removed, the loop would just finish when no more conflicting framebuffers are found. Suggested-by: Daniel Vetter Signed-off-by: Javier Martinez Canillas Reviewed-by: Daniel Vetter --- drivers/video/fbdev/core/fbmem.c | 21 ++++++++++++++------- include/linux/fb.h | 1 - 2 files changed, 14 insertions(+), 8 deletions(-) diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fb= mem.c index b585339509b0..c1bfb8df9cba 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1555,6 +1555,7 @@ static void do_remove_conflicting_framebuffers(struct= apertures_struct *a, { int i; =20 +restart_removal: /* check all firmware fbs and kick off if the base addr overlaps */ for_each_registered_fb(i) { struct apertures_struct *gen_aper; @@ -1582,8 +1583,18 @@ static void do_remove_conflicting_framebuffers(struc= t apertures_struct *a, * fix would add code to remove the device from the system. */ if (dev_is_platform(device)) { - registered_fb[i]->forced_out =3D true; + /* + * Drop the lock since the driver will call to the + * unregister_framebuffer() function that takes it. + */ + mutex_unlock(®istration_lock); platform_device_unregister(to_platform_device(device)); + mutex_lock(®istration_lock); + /* + * Restart the removal now that the platform device + * has been unregistered and its associated fb gone. + */ + goto restart_removal; } else { pr_warn("fb%d: cannot remove device\n", i); do_unregister_framebuffer(registered_fb[i]); @@ -1917,13 +1928,9 @@ EXPORT_SYMBOL(register_framebuffer); void unregister_framebuffer(struct fb_info *fb_info) { - bool forced_out =3D fb_info->forced_out; - - if (!forced_out) - mutex_lock(®istration_lock); + mutex_lock(®istration_lock); do_unregister_framebuffer(fb_info); - if (!forced_out) - mutex_unlock(®istration_lock); + mutex_unlock(®istration_lock); } EXPORT_SYMBOL(unregister_framebuffer); =20 diff --git a/include/linux/fb.h b/include/linux/fb.h index 39baa9a70779..f1e0cd751b06 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -503,7 +503,6 @@ struct fb_info { } *apertures; =20 bool skip_vt_switch; /* no VT switch on suspend/resume required */ - bool forced_out; /* set when being removed by another driver */ }; =20 static inline struct apertures_struct *alloc_apertures(unsigned int max_nu= m) { --=20 2.35.1 From nobody Fri Jun 19 07:16:41 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AB4EBC433F5 for ; Wed, 6 Apr 2022 21:50:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236196AbiDFVwC (ORCPT ); Wed, 6 Apr 2022 17:52:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34316 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234654AbiDFVvL (ORCPT ); Wed, 6 Apr 2022 17:51:11 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id DD1BF8CCFC for ; Wed, 6 Apr 2022 14:40:58 -0700 (PDT) DKIM-Signature: v=1; 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Wed, 06 Apr 2022 14:40:55 -0700 (PDT) Received: from minerva.home ([92.176.231.205]) by smtp.gmail.com with ESMTPSA id o29-20020a05600c511d00b0038e3532b23csm5876020wms.15.2022.04.06.14.40.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Apr 2022 14:40:55 -0700 (PDT) From: Javier Martinez Canillas To: linux-kernel@vger.kernel.org Cc: dri-devel@lists.freedesktop.org, Thomas Zimmermann , Daniel Vetter , Javier Martinez Canillas , Alex Deucher , Guenter Roeck , Helge Deller , Sam Ravnborg , Xiyu Yang , Zhen Lei , linux-fbdev@vger.kernel.org Subject: [RESEND RFC PATCH 4/5] fbdev: Fix some race conditions between fbmem and sysfb Date: Wed, 6 Apr 2022 23:39:18 +0200 Message-Id: <20220406213919.600294-5-javierm@redhat.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220406213919.600294-1-javierm@redhat.com> References: <20220406213919.600294-1-javierm@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The platform devices registered in sysfb match with a firmware-based fbdev or DRM driver, that are used to have early graphics using framebuffers set up by the system firmware. Real DRM drivers later are probed and remove all conflicting framebuffers, leading to these platform devices for generic drivers to be unregistered. But the current solution has two issues that this patch fixes: 1) It is a layering violation for the fbdev core to unregister a device that was registered by sysfb. Instead, the sysfb_try_unregister() helper function can be called for sysfb to attempt unregistering the device if is the one registered. 2) The sysfb_init() function could be called after a DRM driver is probed and requested to unregister devices for drivers with a conflicting fb. To prevent this, disable any future sysfb platform device registration by calling sysfb_disable(), if a driver requested to remove conflicting framebuffers with remove_conflicting_framebuffers(). Suggested-by: Daniel Vetter Signed-off-by: Javier Martinez Canillas Reviewed-by: Daniel Vetter --- drivers/video/fbdev/core/fbmem.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fb= mem.c index c1bfb8df9cba..acf641b05d11 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -1588,7 +1589,10 @@ static void do_remove_conflicting_framebuffers(struc= t apertures_struct *a, * unregister_framebuffer() function that takes it. */ mutex_unlock(®istration_lock); - platform_device_unregister(to_platform_device(device)); + if (!sysfb_try_unregister(device)) { + /* sysfb didn't register this device, unregister it */ + platform_device_unregister(to_platform_device(device)); + } mutex_lock(®istration_lock); /* * Restart the removal now that the platform device @@ -1781,6 +1785,17 @@ int remove_conflicting_framebuffers(struct apertures= _struct *a, do_free =3D true; } =20 + /* + * If a driver asked to unregister a platform device registered by + * sysfb, then can be assumed that this is a driver for a display + * that is set up by the system firmware and has a generic driver. + * + * Drivers for devices that don't have a generic driver will never + * ask for this, so let's assume that a real driver for the display + * was already probed and prevent sysfb to register devices later. + */ + sysfb_disable(); + mutex_lock(®istration_lock); do_remove_conflicting_framebuffers(a, name, primary); mutex_unlock(®istration_lock); --=20 2.35.1 From nobody Fri Jun 19 07:16:41 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 43EECC433EF for ; Wed, 6 Apr 2022 21:50:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236291AbiDFVwG (ORCPT ); Wed, 6 Apr 2022 17:52:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38384 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236387AbiDFVvM (ORCPT ); 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charset="utf-8" From: Daniel Vetter This reverts commit fb561bf9abde49f7e00fdbf9ed2ccf2d86cac8ee. With commit 27599aacbaefcbf2af7b06b0029459bbf682000d Author: Thomas Zimmermann Date: Tue Jan 25 10:12:18 2022 +0100 fbdev: Hot-unplug firmware fb devices on forced removal this should be fixed properly and we can remove this somewhat hackish check here (e.g. this won't catch drm drivers if fbdev emulation isn't enabled). Cc: Thomas Zimmermann Cc: Zack Rusin Cc: Javier Martinez Canillas Cc: Zack Rusin Cc: Hans de Goede Cc: Ilya Trukhanov Signed-off-by: Daniel Vetter Cc: Peter Jones Cc: linux-fbdev@vger.kernel.org Signed-off-by: Javier Martinez Canillas --- drivers/video/fbdev/efifb.c | 11 ----------- drivers/video/fbdev/simplefb.c | 11 ----------- 2 files changed, 22 deletions(-) diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c index ea42ba6445b2..edca3703b964 100644 --- a/drivers/video/fbdev/efifb.c +++ b/drivers/video/fbdev/efifb.c @@ -351,17 +351,6 @@ static int efifb_probe(struct platform_device *dev) char *option =3D NULL; efi_memory_desc_t md; =20 - /* - * Generic drivers must not be registered if a framebuffer exists. - * If a native driver was probed, the display hardware was already - * taken and attempting to use the system framebuffer is dangerous. - */ - if (num_registered_fb > 0) { - dev_err(&dev->dev, - "efifb: a framebuffer is already registered\n"); - return -EINVAL; - } - if (screen_info.orig_video_isVGA !=3D VIDEO_TYPE_EFI || pci_dev_disabled) return -ENODEV; =20 diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c index 94fc9c6d0411..0ef41173325a 100644 --- a/drivers/video/fbdev/simplefb.c +++ b/drivers/video/fbdev/simplefb.c @@ -413,17 +413,6 @@ static int simplefb_probe(struct platform_device *pdev) struct simplefb_par *par; struct resource *res, *mem; =20 - /* - * Generic drivers must not be registered if a framebuffer exists. - * If a native driver was probed, the display hardware was already - * taken and attempting to use the system framebuffer is dangerous. - */ - if (num_registered_fb > 0) { - dev_err(&pdev->dev, - "simplefb: a framebuffer is already registered\n"); - return -EINVAL; - } - if (fb_get_options("simplefb", NULL)) return -ENODEV; =20 --=20 2.35.1