[PATCH 4/8] fbdev: sm712fb: fix boot screen glitch when sm712fb replaces VGA.

Yifeng Li
2019-03-16T22:25:00Z

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>
Cc: stable@vger.kernel.org # v4.4+
---
drivers/video/fbdev/sm712fb.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

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)
--
2.20.1