From: Yifeng Li <tomli@tomli.me>
Date: Mon, 1 Apr 2019 15:46:59 +0000 (+0200)
Subject: fbdev: sm712fb: fix boot screen glitch when sm712fb replaces VGA
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=ec1587d5073f29820e358f3a383850d61601d981;p=openwrt%2Fstaging%2Fblogic.git

fbdev: sm712fb: fix boot screen glitch when sm712fb replaces VGA

When the machine is booted in VGA mode, loading sm712fb would cause
a glitch of random pixels shown on the screen. To prevent it from
happening, we first clear the entire framebuffer, and we also need
to stop calling smtcfb_setmode() during initialization, the fbdev
layer will call it for us later when it's ready.

Signed-off-by: Yifeng Li <tomli@tomli.me>
Tested-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Cc: Teddy Wang <teddy.wang@siliconmotion.com>
Cc: <stable@vger.kernel.org>  # v4.4+
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
---

diff --git a/drivers/video/fbdev/sm712fb.c b/drivers/video/fbdev/sm712fb.c
index 1a3d232c2916..e8149f0f47d5 100644
--- a/drivers/video/fbdev/sm712fb.c
+++ b/drivers/video/fbdev/sm712fb.c
@@ -1493,7 +1493,11 @@ static int smtcfb_pci_probe(struct pci_dev *pdev,
 	if (err)
 		goto failed;
 
-	smtcfb_setmode(sfb);
+	/*
+	 * The screen would be temporarily garbled when sm712fb takes over
+	 * vesafb or VGA text mode. Zero the framebuffer.
+	 */
+	memset_io(sfb->lfb, 0, sfb->fb->fix.smem_len);
 
 	err = register_framebuffer(info);
 	if (err < 0)