linux-kernel - [PATCH] drivers/firmware: fix sysfb depends to prevent build failures

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Date:   Thu, 22 Jul 2021 06:41:55 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     dri-devel <dri-devel@...ts.freedesktop.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Peter Robinson <pbrobinson@...il.com>,
        Javier Martinez Canillas <javierm@...hat.com>,
        kernel test robot <lkp@...el.com>,
        Borislav Petkov <bp@...e.de>,
        Dinh Nguyen <dinguyen@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        He Ying <heying24@...wei.com>,
        John Stultz <john.stultz@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Nicolas Saenz Julienne <nsaenz@...nel.org>
Subject: [PATCH] drivers/firmware: fix sysfb depends to prevent build failures

The Generic System Framebuffers support is built when the COMPILE_TEST
option is enabled. But this wrongly assumes that all the architectures
declare a struct screen_info.

This is true for most architectures, but at least the following do not:
arc, m68k, microblaze, openrisc, parisc and s390.

By attempting to make this compile testeable on all architectures, it
leads to linking errors as reported by the kernel test robot for parisc:

  All errors (new ones prefixed by >>):

     hppa-linux-ld: drivers/firmware/sysfb.o: in function `sysfb_init':
     (.init.text+0x24): undefined reference to `screen_info'
  >> hppa-linux-ld: (.init.text+0x28): undefined reference to `screen_info'

To prevent these errors only allow sysfb to be built on systems that are
going to need it, which are x86 BIOS and EFI.

The EFI Kconfig symbol is used instead of (ARM || ARM64 || RISC) because
some of these architectures only declare a struct screen_info if EFI is
enabled. And also, because the sysfb code is only used for EFI on these
architectures. For !EFI the "simple-framebuffer" device is registered by
OF when parsing the Device Tree Blob (if a DT node for this is defined).

Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>
---

 drivers/firmware/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index af6719cc576..897f5f25c64 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -254,7 +254,7 @@ config QCOM_SCM_DOWNLOAD_MODE_DEFAULT
 config SYSFB
 	bool
 	default y
-	depends on X86 || ARM || ARM64 || RISCV || COMPILE_TEST
+	depends on X86 || EFI

 config SYSFB_SIMPLEFB
 	bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
-- 
2.31.1