From patchwork Thu Oct 26 13:53:03 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hans de Goede X-Patchwork-Id: 13437600 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7C32C2D049 for ; Thu, 26 Oct 2023 13:53:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QiVJTlfw" Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A3B6BD for ; Thu, 26 Oct 2023 06:53:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1698328398; 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; bh=0FdxtQ3dQEGH7WLEFe+olpxwuofCY8+lrXJ9vtnZ3wc=; b=QiVJTlfwC7jW87EZYIdXQPlGwekP2YGlVWJojZqi34hcFQNPhycDEg/YhOGkkoSoT5mllV BE/BRTVcROKGTQ/myW0CpvUiLw2HHHNDrtHMq/XIMS9LJ2TlF09Yt+GeT2KOwO1wLm2cVN aLR8NMV0WR/xxhmM0O0EhQ18wpFr5FY= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-611-aIDz7ZLnM8iulsLYLhzndw-1; Thu, 26 Oct 2023 09:53:07 -0400 X-MC-Unique: aIDz7ZLnM8iulsLYLhzndw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C8DB61C03D98; Thu, 26 Oct 2023 13:53:06 +0000 (UTC) Received: from x1.localdomain.com (unknown [10.39.194.86]) by smtp.corp.redhat.com (Postfix) with ESMTP id AB4961C060AE; Thu, 26 Oct 2023 13:53:05 +0000 (UTC) From: Hans de Goede To: "Rafael J . Wysocki" Cc: Hans de Goede , linux-acpi@vger.kernel.org Subject: [PATCH] ACPI: video: Add comment about acpi_video_backlight_use_native() usage Date: Thu, 26 Oct 2023 15:53:03 +0200 Message-ID: <20231026135303.48757-1-hdegoede@redhat.com> Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.7 Add a comment explaining that acpi_video_backlight_use_native() MUST only be used by GPU drivers and that it must NOT be used on other places. Signed-off-by: Hans de Goede --- The main reason for writing this patch is that some recent submitted patches actually were using acpi_video_backlight_use_native() wrong. --- include/acpi/video.h | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/include/acpi/video.h b/include/acpi/video.h index 4230392b5b0b..3d538d4178ab 100644 --- a/include/acpi/video.h +++ b/include/acpi/video.h @@ -75,6 +75,15 @@ static inline enum acpi_backlight_type acpi_video_get_backlight_type(void) return __acpi_video_get_backlight_type(false, NULL); } +/* + * This function MUST only be called by GPU drivers to check if the driver + * should register a backlight class device. This function not only checks + * if a GPU native backlight device should be registered it *also* tells + * the ACPI video-detect code that native GPU backlight control is available. + * Therefor calling this from any place other then the GPU driver is wrong! + * To check if GPU native backlight control is used in other places instead use: + * if (acpi_video_get_backlight_type() == acpi_backlight_native) { ... } + */ static inline bool acpi_video_backlight_use_native(void) { return __acpi_video_get_backlight_type(true, NULL) == acpi_backlight_native;