From 263903a78ebb6a34433e7c26b918492c523a81ab Mon Sep 17 00:00:00 2001 From: Yifeng Li Date: Mon, 1 Apr 2019 17:46:58 +0200 Subject: [PATCH] fbdev: sm712fb: fix VRAM detection, don't set SR70/71/74/75 commit dcf9070595e100942c539e229dde4770aaeaa4e9 upstream. On a Thinkpad s30 (Pentium III / i440MX, Lynx3DM), the amount of Video RAM is not detected correctly by the xf86-video-siliconmotion driver. This is because sm712fb overwrites the GPR71 Scratch Pad Register, which is set by BIOS on x86 and used to indicate amount of VRAM. Other Scratch Pad Registers, including GPR70/74/75, don't have the same side-effect, but overwriting to them is still questionable, as they are not related to modesetting. Stop writing to SR70/71/74/75 (a.k.a GPR70/71/74/75). Signed-off-by: Yifeng Li Tested-by: Sudip Mukherjee Cc: Teddy Wang Cc: # v4.4+ Signed-off-by: Bartlomiej Zolnierkiewicz Signed-off-by: Greg Kroah-Hartman --- drivers/video/fbdev/sm712fb.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/video/fbdev/sm712fb.c b/drivers/video/fbdev/sm712fb.c index e4836bbeb9d1..7dcf94fbc3b0 100644 --- a/drivers/video/fbdev/sm712fb.c +++ b/drivers/video/fbdev/sm712fb.c @@ -1145,7 +1145,9 @@ static void sm7xx_set_timing(struct smtcfb_info *sfb) /* init SEQ register SR30 - SR75 */ for (i = 0; i < SIZE_SR30_SR75; i++) if ((i + 0x30) != 0x30 && (i + 0x30) != 0x62 && - (i + 0x30) != 0x6a && (i + 0x30) != 0x6b) + (i + 0x30) != 0x6a && (i + 0x30) != 0x6b && + (i + 0x30) != 0x70 && (i + 0x30) != 0x71 && + (i + 0x30) != 0x74 && (i + 0x30) != 0x75) smtc_seqw(i + 0x30, vgamode[j].init_sr30_sr75[i]); -- 2.20.1